1. The value of the live load on the floor is incorrect.
The live load on the floor with incorrect value mainly includes the live load on the balcony, walkway, hallway, stairs, elevator public annex and fire evacuation stairs.
The possible crowded buildings mainly refer to schools, public buildings and high-rise buildings. The standard values of common floor live loads that are not specified in civil buildings are as follows: 4KN/㎡ bathrooms with bathtubs and toilets; 8KN/㎡ public bathrooms with separate squatting toilets (including fillers and partition walls) or are considered according to actual conditions; 3KN/㎡ step classrooms and microcomputer rooms; 10KN/㎡ bank vaults, distribution rooms, and pump rooms; 5KN/㎡ construction loads of the first floor of the underground floor; the loads of the pipes and equipment under the floor are considered according to actual conditions and shall not be less than 0.5KN/㎡; large kitchens in hotels and restaurants shall not be less than 8KN/㎡ or there are heavier stoves, equipment and materials, and should be used according to actual conditions.
"Building Structure Load Specification" GB50009-2012 Article 5.1.1 .
2. The basic wind pressure and basic snow pressure are incorrect.
High-rise buildings that are more sensitive to wind loads (generally considered high-rise buildings with a height of more than 60m) should be designed at 1.1 times the basic wind pressure. Calculate the displacement based on the basic wind pressure once in 50 years, and calculate the structural wind vibration comfort based on the standard value of the wind load once in 10 years.
Structures that are sensitive to snow loads are mainly large span, lightweight roof structures. The snow loads of such structures are often controlled loads, and snow pressure should be used for 100-year recurrence period.
When determining the basic air pressure of the steel structure of the gantry rigid frame light house, it should be multiplied by 1.05 according to the current national standard "Building Structure Load Specification" GB 50009.
"Construction of Building Structure Load Code" GB50009-2012 Article 7.1.1, Article 7.1.2, Article 8.1.1, Article 8.1.2;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 4.2.2.
3. When designing floor beams, walls, columns and foundations, load reduction was not carried out according to the specifications.
This is to consider that the live load on the floor cannot fill all floors at the same time. If the reduction is not made, the foundation design will be too conservative and the calculation of the internal force and reinforcement of the column are incorrect. The new Dutch Regulations have been revised. The reduction of live load on fire trucks when designing floor beams, walls, columns and foundations is not included in the mandatory provisions.
"Building Structure Load Specification" GB50009-2012 Article 5.1.2 .
4. Various buildings in major, middle and primary schools, considering the dense flow of people, the horizontal bearing capacity is not checked for the balcony, stairs, stands, exterior corridors and roof railings or railings. The specified horizontal load should be applied to the top of the railing according to specifications, and the strength of the components should be checked.
"Building Structure Load Specification" GB50009-2012 Article 5.5.2 .
5. The basement retaining wall is a stressed component mainly subject to horizontal soil pressure. The basic combination does not consider the basic combination of permanent load control. The sub-coefficient of permanent load should be 1.35. When calculating the water resistance of the basement base plate, the load sub-coefficient of the self-weight of the plate and soil covered is 1.2, which should be taken as 1.0.
When the ratio of the standard value of the permanent load to the standard value of the variable load is large, when performing the basic combination effect combination design value of the ultimate state of the load capacity, the most unfavorable combination of permanent load effect control should be considered. When calculating the water resistance of the basement floor, the self-weight of the plate and soil covering are beneficial to the structure, and the load sub-coefficient of the self-weight should be 1.0.
The soil pressure of the basement retaining wall should be taken as the stationary soil pressure.
The permanent load sub-coefficient coefficient of the basement exterior wall required by human defense is 1.2 when the structure is unfavorable, and 1.0 when it is favorable; the sub-coefficient coefficient of the anti-explosion equivalent load is 1.0.
When calculating the basement exterior wall, the living load on the outdoor floor is generally not less than 5 KN/㎡.
"Building Structure Load Specification" GB50009-2012 Article 3.2.4 .
6. For public buildings with flexible partition wall layout and decoration practices, partition wall loads are not considered, or the limits of partition wall materials and decoration loads are not indicated.
For non-fixed partition wall loads, 1/3 of the wall weight per extended meter should be used as the floor live load and the added value should not be less than 1KN/㎡.
The line load of the fixed partition wall should be converted into equivalent uniform permanent load.
"Building Structure Load Code" GB50009-2012 Article 5.1.1 Note 6.
7. When using a light roof with a press-shaped steel plate, 0.5 kN/m2 should be taken when calculating the live load of the roof.
For rigid frame components with horizontal projection area greater than 60m2, the standard value of the roof solid uniform live load can be taken less than 0.3KN/㎡.
"Technical Regulations for Steel Structure of Gate-type Rigid Frame Lightweight Houses" CECS 102:2002 Article 3.2.2 .
8. The wind load on the daughter wall was missed when calculating the wind load in the gantry rigid frame factory.
For gantry rigid frame houses, the wind load perpendicular to the surface of the building should be calculated according to Appendix A of the "Gallery rigid frame Regulations".
"Technical Regulations on Steel Structure of Gate-type Rigid Frame Lightweight Houses" CECS102:2002 Article 3.2.3 .
9. The standard value of the roof living load is incorrect.
For example: the standard value of the live load on the roof of the upper person is based on the situation of not being raised; the roof for other purposes is not based on the floor load of the corresponding application; the standard value of the live load on the roof with a roof garden does not take into account the weight of the material such as the garden soil and stone; when there are upper beams on the roof, the possible accumulated water load is not considered in the design, and the water load on the roof area can be 2 KN/㎡, and it is not combined with the live load.
The high and low roofs are in the low roof, temporary loads of the construction pile load of not less than 4KN/m2, and noted in the construction drawings.
"Building Structure Load Specification" GB50009-2012 Article 5.3.1 .
10. The fortification intensity (designed basic earthquake acceleration) is selected incorrectly.
The intensity of earthquake resistance must be determined according to the authority stipulated by the state. In general, the design is based on the fortification intensity, design basic seismic acceleration and design seismic grouping provided in Appendix A of the earthquake resistance specifications.
For cities that have prepared seismic fortification zones, seismic fortification can be carried out according to the approved seismic fortification intensity or designed seismic parameters. However, as towns expand, construction projects are becoming increasingly far away from the center of the town. Construction projects that are far away from the center of the town, especially construction projects that are in the direction of high fortification intensity, may require seismic fortification according to higher standards.
For example: Miyun, Huairou, Changping , Mentougou in Beijing. Appendix A of the "Seismic Anti-Seismic Specifications" gives 7 degrees (0.15g), but the four town centers may need to be fortified at 8 degrees (0.2g) towards the center of Beijing. Generally, these villages and towns that are seismically protected by higher standards are located within 4km areas on both sides of the earthquake peak acceleration dividing line.
"Construction Seismic Design Code" Article 1.0.4 .
11. There is a diagonal anti-lateral force member with an angle greater than 150, and the horizontal seismic effect calculation in the direction of the diagonal anti-lateral force member is not performed.
has a structure of oblique anti-lateral force members. Considering that earthquakes may come from any direction, it is required to calculate the horizontal seismic effect of the anti-lateral member direction with an intersection angle greater than 150. The computer results generally output the angle of the maximum seismic action direction. When its value is large, the seismic action calculation of the seismic action direction is not performed. Earthquake action is multidirectional, and there is always one direction with the greatest effect. When it is greater than 150, the maximum seismic effect calculation should be performed in this direction, and the construction drawings should be designed and drawn based on this larger calculation result.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.1 .
12. The large span and long cantilever structure with an intensity of 8 or 9 degrees of seismic protection have not been calculated vertical seismic. The large span and long cantilever structures in 7-degree (0.15g) high-rise buildings should also be calculated vertical seismic effects.
The vertical seismic action needs to be calculated. The conversion components of the conversion structure, the connecting body of the connecting structure when the seismic design is 7 degrees (0.15g) and 8 degrees, and the high-rise buildings when the seismic resistance is 9 degrees.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.1 .
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 Article 4.3.2, Section 10.5.2.
13. The structure self-vibration period used to calculate the seismic impact coefficient in structure does not consider the stiffness influence of the non-load-bearing wall to be reduced.
Considering the contribution of masonry filling walls to the lateral stiffness of the structure, the calculated self-vibration period must be reduced according to Article 4.3.17 of the High Regulations.
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 No. 4.3.16.
14. When evaluating earthquake resistance, the shear coefficient of any floor should comply with the requirements of Article 5.2.5 of the "Seismic Code". If multiple floors are not met, it is inappropriate to just adjust the minimum seismic shear coefficient of the floor.
If the shear coefficients on multiple floors are not satisfied, it means that the lateral stiffness of the structure is insufficient, and the lateral stiffness of the structural system should be increased.
should also be noted: when the bottom shear force is not much different, the multiplied by the increase coefficient can be used according to the specifications; when the bottom shear force is much different, the selection and overall layout of the structure need to be readjusted, and it cannot be processed by the multiplied by the increase coefficient.
For vertical irregular structures, the weak layer of the mutation site should also be multiplied by a coefficient not less than 1.15 according to Article 3.4.4 of the earthquake resistance specification.
"Construction Seismic Design Code" GB50011-2010 Article 5.2.5 .
15. The construction site category is incorrect. The calculation book and drawings are all Class 2 soil. The geological survey report is Class 2, and the structural calculation should be recalculated.
Site category is related to calculating the seismic impact coefficient of earthquake action. Incorrect site category will lead to incorrect seismic effect calculation.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.4 .
16. Single-story factory only considers horizontal horizontal seismic effects, but does not calculate horizontal seismic effects of the vertical direction of the factory.
Generally speaking, horizontal seismic action should be calculated separately in at least two main axial directions of the building structure, and horizontal seismic action in each direction should be borne by the lateral force-resistant components in that direction.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.1 .
17. The building structure with obviously asymmetric and uneven mass and stiffness distributions, and the torsional effect under the action of bidirectional horizontal earthquake was not calculated during seismic calculations.
"Structure with obviously asymmetric and uneven mass and stiffness distribution", generally refers to the ratio of the maximum displacement to the average displacement of the floor exceeds the lower limit of the displacement ratio of 1.2 under the assumption of rigid floor slabs, under the action of accidental eccentric one-way horizontal earthquakes and earthquakes.
calculates the bidirectional horizontal seismic effect and considers the torsional impact and calculates the one-way horizontal seismic effect and considers the accidental eccentric effect and takes the most adverse consideration. For multi-story buildings, any irregular multi-story buildings referred to in Article 3.4.2 of the earthquake resistance specification should also be considered as the influence of accidental eccentricity.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.1 .
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 4.3.1 .
2. Foundation
1. Buildings with design grades A or Class B or non-embedded rock piles with design grades A and non-deep hard holding layer are considered to be deformed and verification based on pile test test results and design experience, so no settlement calculation results are provided.
Article 3.0.2, paragraphs 2 and 3 of the "Soil Code" have clear provisions on the scope of verification of building foundation deformation, and the design should be strictly followed. Experience cannot replace laws and regulations, settlement calculations should be carried out in accordance with regulations.
"Construction Foundation Design Code" GB50007-2011 Article 3.0.2 .
2. No safety requirements were put forward for foundation pit excavation.
should write specific requirements in the general structure description or foundation pit excavation diagram according to Article 9.1.9.
"Construction Foundation Design Code" GB50007-2011 No. 9.1.9.
3. Do not check whether the concrete strength of the pile body meets the pile test requirements. The concrete strength of the pile body should meet the pile bearing capacity design requirements.
"Construction Foundation Design Code" GB50007-2011 No. 8.5.10.
4. Buildings with a design level of Class B on composite foundations or weak foundations have no settlement observation points and no deformation observation requirements have been proposed (there are many such problems in 8th and 9th floor buildings).
buildings with a design level of Class B on composite foundations or weak foundations must undergo deformation observations during construction and use periods as required.
"Construction Foundation Design Code" GB50007-2011 No. 10.3.8.
5. The foundation groove (pit) inspection should be carried out after the foundation pit is excavated to the design elevation. After excavation of the foundation groove (pit), the foundation groove inspection should be carried out.Base groove inspection can be used for touch detection or other methods. When it is found that it is inconsistent with the survey report and design documents, or abnormal situations are encountered, handling opinions should be put forward in light of geological conditions.
"Construction Foundation Design Code" GB50007-2011 No. 10.2.1.
6. Considering geological conditions, "focus on monomers and neglects the environment", it is not considered that mountainous buildings and structures may suffer adverse effects such as landslides, collapses, mudslides, and heavy rainfall.
site selection and positioning are reasonably avoided, and the foundation and superstructure are appropriately strengthened. In areas affected by mountain torrents, corresponding flood discharge measures should be taken. Landslides that have development trends and threaten the safe use of buildings should be rectified as soon as possible to prevent the landslide from continuing to develop.
"Construction Foundation Design Code" GB50007-2011 Article 6.1.1, Article 6.1.4 .
7. Ignore the verification of the load bearing capacity and shear bearing capacity of the beam-slab-type raft base plate.
"Construction Foundation Design Code" GB50007-2011 Article 8.4.11 .
8. The thickness of the concrete structure at the deformation joint should not be less than 300mm.
Because the deformation joint is a weak link in waterproofing, especially when the medium-buried water stop is used, the water stop divides the concrete here into two parts, which will adversely affect the concrete at the deformation joint. Therefore, the regulations on local thickening of the concrete at the deformation joint.
"Technical Specifications for Waterproofing of Underground Engineering" GB 50108-2008 Article 5.1.3 .
9. Ignore the necessary deformation verification after foundation treatment; or replace the foundation deformation verification with the settlement estimate in the geological survey report.
The scope of deformation verification of the processed foundation is the same as that of the "Code for Design of Building Foundations" No. 3.0.2.
"Technical Specifications for Building Foundation Treatment" JGJ79-2002 Article 3.0.5 .
10. The construction quality inspection requirements for replacement cushion layer are unknown.
should be noted in the figure that the construction quality inspection of the cushion layer must be carried out in layers, and the layer of soil should be filled after the compaction coefficient of each layer meets the design requirements.
"Technical Specifications for Building Foundation Treatment" JGJ79-2002 Article 4.4.2 .
11, the quality inspection requirements for the construction of CFG pile composite foundation are inaccurate, and the characteristic value detection requirements for the bearing capacity of the composite foundation are proposed according to the modified bearing capacity characteristic value fa.
should provide inspection requirements according to the composite foundation bearing capacity characteristic value fspk before depth and width correction.
"Technical Specifications for Building Foundation Treatment" JGJ79-2002 Article 9.4.2 .
12. The general structure description of buildings on the wet loess site does not require use, maintenance and maintenance requirements.
should be noted in the design: During use, buildings and pipelines should be maintained and repaired regularly, and all waterproofing measures should be ensured to prevent water invasion and descent of the foundation of buildings and pipelines.
"Building Code for Sinking Loess Areas" GB50025-2004 Article 9.1.1 .
13. The pile foundation calculation book is not comprehensive. Such as calculation of the horizontal bearing capacity of pile foundation; calculation of the pull-out bearing capacity of anchor piles; calculation of the bearing capacity of pile body and bearing structure, etc.
should provide a calculation book according to the calculation items required by Article 3.1.3 of the Pile Foundation Specification to review whether the pile foundation design is safe and reasonable.
"Technical Specifications for Building Pile Foundations" JGJ 94-2008 Article 3.1.3 .
14. When the concrete strength level of the foundation (including the bearing) is less than the concrete strength level of the column or pile, the local pressure bearing capacity of the foundation is not verified.
local pressure bearing capacity verification is generally calculated according to Appendix D.5 of the local pressure concrete in " Concrete Structure Design Specification ". When the requirements are not met, the concrete strength level can be increased or the indirect steel bars (reinforced mesh or spiral reinforcement) can be used to calculate according to Section 6.6 of the "Concrete Code".
"Construction Foundation Design Code" GB50007-2011 Article 8.2.7, Article 8.4.18, Article 8.5.22 .
15. When calculating the foundation bearing capacity, the load effect standard combination was not used; when designing the foundation bearing capacity, the load effect basic combination was not used.
When verifying the foundation bearing capacity and foundation bearing capacity, different load effect combinations should be used respectively.
"Construction Foundation Design Code" GB50007-2011 Article 3.0.5 .
16. Buildings and structures built on slopes or near slopes have not been verified.
buildings and structures built on slopes or near slopes only verify the bearing capacity and deformation of the foundation and the slope stability verification is ignored, and the stability calculation should be carried out in accordance with the provisions of 5.4 of the "Structure Code".
"Construction Foundation Design Code" GB50007-2011 Article 3.0.2 .
17. When the load difference in the same structural unit is very large or is placed on an uneven soil layer, and there is ground loading on the foundation and near the ground, the foundation foundation design only meets the bearing capacity requirements and no foundation deformation calculation is performed.
should be checked for foundation settlement amount, settlement difference, inclination and local inclination according to Section 5.3 of the "Structure Code" respectively. The impact of settlement difference should be considered in the foundation and superstructure.
"Construction Foundation Design Code" GB50007-2011 Article 3.0.2 and Article 5.3.4 .
18. Design the overall foundation of the large chassis under the multi-tower and podium, and only the foundation settlement under the tower is calculated separately.
has multiple high-rise and low-rise buildings built on the same large area. The foundation deformation calculation should be carried out according to the superstructure, foundation and foundation joint action, which complies with Article 5.3.10 of the "Structure Code" and meets the requirements of Article 5.3.4 of the "Structure Code".
"Construction Foundation Design Code" GB50007-2011 Article 5.3.4 .
19. The foundation holding layer is set on the untreated liquefied soil layer;
Buildings built on the liquefied soil layer have many examples of foundation instability during earthquakes and buildings collapse or damage. The level of liquefaction is different, and the degree of earthquake damage is also different. For anti-liquefaction measures, see Articles 4.3.6~4.3.9 of the "Seismic Code".
"Construction Seismic Design Code" Article 4.3.2 .
20. The encryption range of pile stirrups does not meet the specification requirements.
pile stirrup should comply with the relevant provisions and requirements of Article 4.4.5 of the "Seismic Resistance Code" and Chapter 4 of the "Seismic Foundation Code".
"Construction Seismic Design Code" Article 4.4.5 .
21. When the groundwater level is high (groundwater is buried shallow), there is a problem of floating up the building's basement or underground structure, and no anti-float verification is carried out.
anti-floating stability verification is calculated according to Article 5.4.3 of the "Structure Foundation Specifications". Measures to increase structural stiffness can also be used when the overall requirements of anti-floating stability are met but locally not met.
drawing documents should also indicate the time for stopping precipitation during construction. It should also be noted that the anti-float design water level is different from the anti-water design water level.
"Construction Foundation Design Code" GB50007-2011 Article 3.0.2 .
3. Masonry
1. The number or height of the masonry structure exceeds the specification limit.
limit.
earthquake damage survey shows that the more floors and heights of masonry houses, the more serious the earthquake damage. The new seismic specification adds layer counts and height limits of 7 degrees (0.15 g) and 8 degrees (0.3 g).
Bottom Frame- Seismic Wall Masonry Houses are not allowed to be used in Class B buildings and Class C buildings of 8 degrees (0.3g). When
6 or 7 degrees, after taking strengthening measures in accordance with Article 7.3.14 of the earthquake resistance specification, the number and height of the floors will still be adopted according to the provisions of Table 7.1.2 of the earthquake resistance specification.
The total height of masonry houses with fewer horizontal walls is reduced by 3m according to the specification table 7.1.2, and the number of layers is reduced by one layer; there should be one layer when there are fewer horizontal walls. The new anti-regulation stipulates the meaning of "few horizontal walls" and "few horizontal walls".
For sloped roofs with attics, they should be calculated to be 1/2 of the height of the pointed wall. (a) The attic in the figure is not used as one floor, and its height is included in the height of the slope roof; (b) The attic in the figure is as one floor, and its height is included in the height of the slope roof; (c) The "small building" on the roof under the slope roof (the actual effective usable area or representative value of gravity load is less than 30% of the top floor) can not be included in the number of floors and height control range.
The total height of a house refers to the height from the outdoor floor to the main roof panel roof or eaves. The semi-basement starts from the indoor floor of the basement, and the entire basement and semi-basement with good embedded conditions should be allowed to start from the outdoor floor.Whether it is a full basement or a semi-basement, the seismic strength verification should be used as a first floor and meet the wall bearing capacity requirements.
"Construction Seismic Design Code" GB50011-2010 7.1.2 ;
" Masonry Structure Design Code " GB50003-2011 10.1.2 .
2. Bottom frame - seismic wall masonry house, the layout and quantity of bottom seismic walls do not meet the specification requirements.
Bottom frame - Seismic wall masonry house is an unfavorable architectural structure system. The upper and lower layers are composed of different materials, and the stiffness of the upper and lower layers is relatively different. This structure is economically adopted, but measures must be taken to ensure seismic safety.
Bottom frame - Seismic wall The maximum spacing of the seismic wall at the lower part of the masonry house exceeds the specification requirements.
The bottom seismic wall should be set in a certain number along the vertical and horizontal directions and arranged evenly and symmetrically. The ratio of the lateral stiffness of the second layer to the bottom layer should not be greater than 2.5 at 6 or 7 degrees, and should not be greater than 2.0 at 8 degrees, and should not be less than 1.0. The lateral stiffness ratio of the floor of the seismic wall brick masonry house does not meet the specification requirements; it is advisable to adjust the length of the seismic wall or open a hole in the seismic wall to adjust the lateral stiffness of the wall to meet the requirements.
specification stipulates that the bottom seismic wall bears all seismic force, and as a safety reserve, it also requires that the framework should also be designed to bear 20% of the seismic force.
"Construction Seismic Design Code" GB50011-2010 Articles 7.1.5, 7.1.8, and 7.2.4 .
3. The seismic structure of the masonry house supporting wall beam does not meet the requirements.
bottom frame seismic wall masonry house supporting wall beam is an extremely important component in this structure. The strength and stiffness of the supporting wall beam must be ensured. The specification stipulates that the cross-sectional width of the beam should not be less than 300mm, and the cross-sectional height of the beam should not be less than 1/10 of the span. This is to ensure the overall stiffness of the supporting wall beam.
In addition, considering the repetition of earthquake effects, it is also required that the stressed reinforcement and waist reinforcement should be anchored in the column according to the requirements of the tensioned reinforcement bar, and the anchoring length of the upper longitudinal reinforcement in the column should meet the relevant requirements of the reinforced concrete frame support beam; waist reinforcement should be installed along the beam height, the number should not be less than 2Ф14, and the spacing should not be greater than 200mm; the spacing should not be greater than 100mm in the encrypted area, and the diameter should not be less than 8mm. In addition to encrypting the static span of the beam at the end of the beam, the stirrup should also be encrypted within the range of 500mm at the opening of the upper wall and the sides of the opening of the hole.
"Construction Seismic Design Code" GB50011-2010 7.5.8.
4, bottom frame - seismic wall masonry house frame structure, the upper masonry seismic wall is aligned with the bottom frame beam or seismic wall, or basic alignment, and it is difficult to meet the specification requirements.
"Construction Seismic Design Code" GB50011-2010 7.1.8 items.
5. The adjustment coefficient γa of the masonry strength design value is ignored.
The adjustment coefficient of the masonry strength design value is related to the safety of the structure. The adjustment coefficient of the masonry strength design value mainly involves the area adjustment coefficient and the cement mortar adjustment coefficient. Tests show that medium and high-strength cement mortar has no adverse effect on the compressive strength of the masonry and the shear strength of the masonry. When cement mortar greater than M5 is used, the masonry strength can not be adjusted.
"Masonry Structure Design Code" GB50003-2011 Article 3.2.3 .
6. In the design of multi-layer masonry houses, the role of structural column as the main seismic structural measure is ignored, and structural columns are not set up according to the requirements of the specifications.
"Seismic Resistance Specifications" strengthens the seismic structural measures of stairwells. The structural columns added at the corresponding walls at the upper and lower ends of the stairwells have eight structural columns in total, and the structural columns set at the four corners of the stairwell, and then form an emergency evacuation safety island with the concrete reinforced belt set at half the height of the floor.
"Construction Seismic Design Code" GB50011-2010 Article 7.3.1 and Article 7.4.1 .
7. Reinforced concrete floor slabs are assembled integral floor slabs, and ring beams also mistakenly made prefabricated floor slabs; cast-in-place floor slabs may not be equipped with ring beams, but the floor slabs do not strengthen the steel bars along the periphery of the wall; prefabricated floor slabs only have peripheral ring beams on the exterior wall, and no ring beams on the inner wall.
ring beams can enhance the integrity of the house and improve the seismic resistance of the house. They are effective seismic resistance measures. The seismic ring beam must be cast in place.An example of prefabricated ring beam damage was found in earthquake areas. During earthquakes, the ring beam and the floor slab cannot be reliably bonded, and the ring beam will fall off the floor slab.
cast-in-place floor slabs have good integrity and high horizontal stiffness. Therefore, there is no need to set up another ring beam, but the general steel bars in the floor slab, including distributed steel bars, are not enough to form the frame function of the floor slab. Reinforced steel bars need to be installed and reliablely connected with the structural column steel bars.
Prefabricated floor slabs are only equipped with ring beams on the exterior walls. Longer exterior wall ring beams also need to be tied in the middle section. Seismic-resistant closed ring beams should be installed on the exterior wall, inner vertical wall, and inner horizontal walls according to the specifications. Article 7.3.3 of "Construction Seismic Design Code" GB50011-2010 .
8. As an earthquake-resistant safety island, no earthquake-resistant strengthening measures were taken.
also shows that the stairwell is often damaged seriously due to its relatively empty space, and a series of effective measures must be taken. Prefabricated stairs should not be used at 8 or 9 degrees. The buildings and elevators that protrude the roof are affected by major earthquakes during earthquakes, and the structural measures may be particularly strengthened.
"Construction Seismic Design Code" GB50011-2010 Article 7.3.8 .
9. In prefabricated floors, when there are cast-in-place ring beams, the length of the prefabricated boards extending into the wall does not meet the requirements; the house has a large open room (the opening is greater than 4.2m), and there is a lack of a tie between the building, roof and wall or beam.
The shelving length of the floor slab, the tie between the floor slab and the ring beam, the tie between the wall, the anchoring and tie between the roof slab (beam) and the columns, etc. are important measures to ensure the integrity of the building, the roof and the wall. When the ring beam is installed at the bottom of the plate, the reinforced concrete prefabricated plates should be tied to each other and should be tied to the beam, wall or ring beam. For detailed pictures, see Shaanxi 09G0901-1.
"Construction Seismic Design Code" GB50011-2010 Article 7.3.5 .
10. The roof beams and roof structures in the earthquake area did not take measures to strengthen their resistance.
"Construction Seismic Design Code" GB50011-2010 Article 7.3.6 .
11. In a multi-layer concrete small hollow block house, a structural column system can be used or a core column system can be used. The choice should be treated differently.
"Construction Seismic Design Code" GB50011-2010 Article 7.4.1 .
12. Bottom frame-seismic wall masonry house floor building seismic structural measures do not meet the requirements.
Bottom frame-seismic wall masonry house has different lateral force resistance structural systems from the upper layers. In order to make the floor cover have the stiffness to transmit horizontal seismic force, the bottom plate of the transition layer is required to be cast-in-place floor slabs with a thickness of not less than 120mm, and there should be few holes or small holes. When the hole size of the floor slab is greater than 800mm, side beams should be set up around the opening. The requirements for building buildings on each floor on the upper floor are the same as those for multi-story brick houses.
"Construction Seismic Design Code" GB50011-2010 Article 7.5.7 .
13. Bottom frame-seismic walls are installed on the bottom floor of the masonry house. The walls are built first and then beams and columns are poured as required.
Multi-story masonry houses should also be built first and then poured into structural columns during construction. Bottom frame-seismic wall masonry house floor is set up to constrain ordinary brick masonry or small block masonry seismic walls at 6 degrees and the number of floors of the house does not exceed 4 floors.
"Construction Seismic Design Code" GB50011-2010 Article 3.9.6, Article 7.1.8 .
4. Concrete structure
1, beams, columns, slabs, shear wall The minimum reinforcement rate of stressed steel bars and stirrups does not meet the requirements of the specifications; the reinforcement rate of longitudinal reinforcement of the converted beam is incorrectly designed according to the general frame beam requirements; the minimum total reinforcement rate of frame columns of high-rise buildings built on Class I site with a house height of more than 60m has not increased by 0.1%.
The minimum reinforcement rate does not meet the requirements of the specifications, especially the probability of fat beams, fat columns, thick walls and thick plates appearing.
conversion beams are different from general frame beams: conversion beams are generally eccentric tensioned components and withstand greater shear forces, while general frame beams are curved shear components; conversion beams have large internal forces, while general frame beams have relatively small internal forces; conversion beams have higher ductility requirements during seismic design.
"Concrete Structure Design Code" GB50010-2010 Article 8.5.1, Article 11.3.6, Article 11.4.12, Article 11.7.14 .
"Construction Seismic Design Code" GB50011-2010 Article 6.3.7 and Article 6.4.3 .
"Technical Regulations on Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.3.2, Article 6.4.3, Article 7.2.17, Article 8.2.1, Article 10.2.7, Article 10.2.10, Article 10.2.19 .
2. The seismic resistance level of concrete structure is selected incorrectly.
The seismic resistance level should be used according to the seismic fortification classification, intensity, and structural type of house height.
frame support shear wall structure, the seismic resistance level of the shear wall should be distinguished from the bottom reinforcement area (the key is the height of the frame support layer plus the two layers above the frame support layer) and the seismic resistance level of the non-reinforcement area. When the frame-shear wall is under the action of a specified horizontal force, and the seismic overturning moment borne by the bottom layer (calculate the layer where the embedded end is located) is greater than 50% of the total seismic overturning moment of the structure, the seismic resistance level of the frame should be determined according to the frame structure, and the seismic resistance level of the seismic wall can be the same as the frame's seismic resistance level.
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 3.9.3 .
"Concrete Structure Design Code" GB50010-2010 Article 11.1.3 .
"Construction Seismic Design Code" GB50011-2010 Article 6.1.2, Article 6.1.3.
3, frame beams and conversion beams do not have stirrup encryption areas; when there is a door hole on the upper wall of the conversion beam to form a small wall limb or a pillar on the beam, the stirrups of the conversion beams at this part are not encrypted.
When a multi-layer frame structure is installed with a pull beam layer near the ground below the outdoor ground, the seismic structural measures of the pull beam should also meet the requirements of the frame beam and a stirrup encryption area should be set up.
The bending moment and shear force of the conversion beam at the edge of the hole and the support column are greatly increased; during seismic design, the structure of the full-length stirrup along the connecting beam should be adopted according to the requirements of the frame beam encryption area, and the connecting beam should not be encrypted according to the general frame beam only at a certain range of stirrups at the end of the beam.
"Construction Seismic Design Code" GB50011-2010 ;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.3.2 and Article 10.2.7 .
4. The computer calculation diagram does not match the actual construction drawings, such as the layout and quantity of shear walls, concrete strength grade, beam cross-sectional dimensions, etc.
The calculation sketch does not match the actual construction drawings, which will bring hidden dangers to structural safety. The structural major must cooperate closely with each major and modify the main calculations in a timely manner to ensure that the calculation sketch is consistent with the actual construction drawings.
"Construction Seismic Design Code" GB50011-2010 Article 3.5.2 and Article 3.6.6 .
5. The guarantee rate of the standard value of steel bar strength is not indicated; the special requirements for material and construction quality of seismic structures are not indicated.
In the concrete structure design description, it should be proposed that when the frame and oblique brace components (including stairs) with earthquake resistance levels of one, two or three, and their longitudinal bars are made of ordinary steel bars, the actual measured value of the tensile strength of the steel bar and the actual measured value of the yield strength should not be less than 1.25; the ratio of the actual measured value of the yield strength of the steel bar and the standard value of the yield strength should not be greater than 1.3, and the total elongation of the steel bar under the maximum tensile force should not be less than 9%.
The standard value of reinforcement strength should have a guarantee rate of no less than 95%.
"Construction Seismic Design Code" GB50011-2010 Article 3.9.1 and Article 3.9.2 .
"Concrete Structure Design Code" GB50010-2010 Article 4.2.2 .
6. The seismic fortification classification of building is not correctly determined.
For example: high-rise buildings with large chassis, when the bottom several floors are large supermarkets and meet the standards of large shopping malls, the seismic fortification category has not been designated as the key fortification category (Class B); or the entire building is designated as the Class B; or even if the lower several floors are commercial buildings but do not meet the standards of large shopping malls, they are designated as the key fortification category.
"Classification Standard for Seismic Fortification of Construction Engineering" GB50223-2008 Article 3.0.1 .
"Classification Standard for Seismic Fortification of Construction Engineering" GB50223-2008 Article 3.0.2 .
"Construction Seismic Design Code" GB50011-2010 Article 3.1.1 .
7. The horizontal distribution ribs of the exterior wall of the civil defense basement do not meet the minimum reinforcement rate requirements.
The reinforcement ratio of components with protection requirements is different from that of general components, and should be treated differently during design.
"Civil Air Defense Basement Design Code" GB50038-2005 Article 4.11.7 .
8. During seismic design, the ratio of the bottom reinforcement and the top reinforcement of the end section of the first-level frame beam is less than 0.5, and the second and third-levels are less than 0.3.
level one should be greater than 0.5; levels two and three should be greater than 0.3. The ratio of longitudinal steel bars on the end of the beam and the top surface of the beam has a great impact on the deformation ability of the beam, and can prevent premature yield or serious damage when the positive bending moment appears at the bottom of the beam in an earthquake, thereby affecting the normal performance of bearing capacity and deformation ability.
"Construction Seismic Design Code" GB50011-2010 Article 6.3.3 ;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.3.2 .
9. During seismic design, the reinforcement ratio of longitudinal reinforcement at the end of the frame beam is greater than 2%, but the minimum diameter of stirrups in the end of the beam is not increased by 2mm.
test and earthquake damage show that the damage at the end of the beam is mainly concentrated within the beam height range of 1.5 to 2 times. It is possible to obtain better ductility by limiting the length of the stirrup enlargement area of the beam end, the maximum spacing and minimum diameter of the stirrups. When the reinforcement ratio of the longitudinal reinforcement bar at the end of the frame beam is greater than 2%, the requirements for stirrups are also increased accordingly.
The cantilever sections of the cantilever beam and frame beam do not perform this as the stirrups. For the inner span adjacent to the beam cantilever section, it is recommended to determine the diameter of the stirrup according to whether the gluten of the cantilever support exceeds 2%.
"Construction Seismic Design Code" GB50011-2010 Article 6.3.3 ;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.3.2 .
10. When the first-level earthquake resistance level is used, when the frame beam and column longitudinal bars use steel bars of diameter 16 or 14, if the spacing between stirrups is matched to @100 does not meet the requirements of 6d; when the height of the frame beam is 300, the spacing between stirrups is 100 greater than 1/4 of the beam height, 75 should be taken.
test and earthquake damage show that when the spacing between stirrups is less than 6d to 8d, the compressed steel bars before concrete collapse generally do not cause compression and have better ductility.
"Construction Seismic Design Code" GB50011-2010 Article 6.3.7; Article 6.3.3 .
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 Article 6.4.3, Article 6.3.2 . At the base of the third and fourth-level frame columns, the spacing between stirrups in the encryption area is 150 less than 100 and 8d (d is the diameter of the longitudinal stressed steel bar ).
The spacing of stirrups at the root of the third and fourth-level frame column columns (lower end of the bottom column) should be the smaller values of 100 and d (d is the diameter of the longitudinal stressed steel bar).
"Construction Seismic Design Code" GB50011-2010 Article 6.3.7 ;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.4.3 .
12. During seismic design, no provisions were made on the principle of substitution for longitudinal stressed steel bars in the main structure.
If the principle of substitution of longitudinal stressed steel bars in the main structure is not specified, the total bearing capacity of the replaced longitudinal stressed steel bars will often be greater than the design value of the total bearing capacity of the original design of the longitudinal stressed steel bars, thereby causing the transfer of seismic weak parts, and may also cause concrete brittle damage (concrete crushing, component shear failure) in the affected parts of the components. When replacing longitudinal stressed steel bars, they should be converted according to the principle of equal tensile bearing capacity of the steel bars, and meet the requirements of normal use limit state (cracks, deflection) and seismic structural measures (maximum and minimum reinforcement ratio, protective layer thickness, steel bar spacing, etc.). In particular, when replacing the original design longitudinal stressed steel bars with higher grades, attention should be paid to the impact of changes in the steel bar ductility (strong curve ratio, plastic design conditions, etc.) caused by the above substitution.
"Construction Seismic Design Code" GB50011-2010 Article 3.9.4 .
13. When designing the frame structure, the form of a mixed load bearing of the frame and some masonry walls should not be adopted.
Not only should a frame structure house not be partially masonry-bearing, but the elevator room, elevator machine room, stairwell, water tank room, etc. in the frame structure, should not be load-bearing with masonry walls, but frame load-bearing, and non-load-bearing filling walls should be used. Frame structure and masonry structure are two completely different structural systems. The earthquake damage shows that if used in the same building, masonry walls with lateral stiffness far greater than those of the frame during earthquake will first be damaged, resulting in a sharp increase in the internal force of the frame, and then the frame is damaged or even collapsed.
1. The value of the live load on the floor is incorrect.
The live load on the floor with incorrect value mainly includes the live load on the balcony, walkway, hallway, stairs, elevator public annex and fire evacuation stairs.
The possible crowded buildings mainly refer to schools, public buildings and high-rise buildings. The standard values of common floor live loads that are not specified in civil buildings are as follows: 4KN/㎡ bathrooms with bathtubs and toilets; 8KN/㎡ public bathrooms with separate squatting toilets (including fillers and partition walls) or are considered according to actual conditions; 3KN/㎡ step classrooms and microcomputer rooms; 10KN/㎡ bank vaults, distribution rooms, and pump rooms; 5KN/㎡ construction loads of the first floor of the underground floor; the loads of the pipes and equipment under the floor are considered according to actual conditions and shall not be less than 0.5KN/㎡; large kitchens in hotels and restaurants shall not be less than 8KN/㎡ or there are heavier stoves, equipment and materials, and should be used according to actual conditions.
"Building Structure Load Specification" GB50009-2012 Article 5.1.1 .
2. The basic wind pressure and basic snow pressure are incorrect.
High-rise buildings that are more sensitive to wind loads (generally considered high-rise buildings with a height of more than 60m) should be designed at 1.1 times the basic wind pressure. Calculate the displacement based on the basic wind pressure once in 50 years, and calculate the structural wind vibration comfort based on the standard value of the wind load once in 10 years.
Structures that are sensitive to snow loads are mainly large span, lightweight roof structures. The snow loads of such structures are often controlled loads, and snow pressure should be used for 100-year recurrence period.
When determining the basic air pressure of the steel structure of the gantry rigid frame light house, it should be multiplied by 1.05 according to the current national standard "Building Structure Load Specification" GB 50009.
"Construction of Building Structure Load Code" GB50009-2012 Article 7.1.1, Article 7.1.2, Article 8.1.1, Article 8.1.2;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 4.2.2.
3. When designing floor beams, walls, columns and foundations, load reduction was not carried out according to the specifications.
This is to consider that the live load on the floor cannot fill all floors at the same time. If the reduction is not made, the foundation design will be too conservative and the calculation of the internal force and reinforcement of the column are incorrect. The new Dutch Regulations have been revised. The reduction of live load on fire trucks when designing floor beams, walls, columns and foundations is not included in the mandatory provisions.
"Building Structure Load Specification" GB50009-2012 Article 5.1.2 .
4. Various buildings in major, middle and primary schools, considering the dense flow of people, the horizontal bearing capacity is not checked for the balcony, stairs, stands, exterior corridors and roof railings or railings. The specified horizontal load should be applied to the top of the railing according to specifications, and the strength of the components should be checked.
"Building Structure Load Specification" GB50009-2012 Article 5.5.2 .
5. The basement retaining wall is a stressed component mainly subject to horizontal soil pressure. The basic combination does not consider the basic combination of permanent load control. The sub-coefficient of permanent load should be 1.35. When calculating the water resistance of the basement base plate, the load sub-coefficient of the self-weight of the plate and soil covered is 1.2, which should be taken as 1.0.
When the ratio of the standard value of the permanent load to the standard value of the variable load is large, when performing the basic combination effect combination design value of the ultimate state of the load capacity, the most unfavorable combination of permanent load effect control should be considered. When calculating the water resistance of the basement floor, the self-weight of the plate and soil covering are beneficial to the structure, and the load sub-coefficient of the self-weight should be 1.0.
The soil pressure of the basement retaining wall should be taken as the stationary soil pressure.
The permanent load sub-coefficient coefficient of the basement exterior wall required by human defense is 1.2 when the structure is unfavorable, and 1.0 when it is favorable; the sub-coefficient coefficient of the anti-explosion equivalent load is 1.0.
When calculating the basement exterior wall, the living load on the outdoor floor is generally not less than 5 KN/㎡.
"Building Structure Load Specification" GB50009-2012 Article 3.2.4 .
6. For public buildings with flexible partition wall layout and decoration practices, partition wall loads are not considered, or the limits of partition wall materials and decoration loads are not indicated.
For non-fixed partition wall loads, 1/3 of the wall weight per extended meter should be used as the floor live load and the added value should not be less than 1KN/㎡.
The line load of the fixed partition wall should be converted into equivalent uniform permanent load.
"Building Structure Load Code" GB50009-2012 Article 5.1.1 Note 6.
7. When using a light roof with a press-shaped steel plate, 0.5 kN/m2 should be taken when calculating the live load of the roof.
For rigid frame components with horizontal projection area greater than 60m2, the standard value of the roof solid uniform live load can be taken less than 0.3KN/㎡.
"Technical Regulations for Steel Structure of Gate-type Rigid Frame Lightweight Houses" CECS 102:2002 Article 3.2.2 .
8. The wind load on the daughter wall was missed when calculating the wind load in the gantry rigid frame factory.
For gantry rigid frame houses, the wind load perpendicular to the surface of the building should be calculated according to Appendix A of the "Gallery rigid frame Regulations".
"Technical Regulations on Steel Structure of Gate-type Rigid Frame Lightweight Houses" CECS102:2002 Article 3.2.3 .
9. The standard value of the roof living load is incorrect.
For example: the standard value of the live load on the roof of the upper person is based on the situation of not being raised; the roof for other purposes is not based on the floor load of the corresponding application; the standard value of the live load on the roof with a roof garden does not take into account the weight of the material such as the garden soil and stone; when there are upper beams on the roof, the possible accumulated water load is not considered in the design, and the water load on the roof area can be 2 KN/㎡, and it is not combined with the live load.
The high and low roofs are in the low roof, temporary loads of the construction pile load of not less than 4KN/m2, and noted in the construction drawings.
"Building Structure Load Specification" GB50009-2012 Article 5.3.1 .
10. The fortification intensity (designed basic earthquake acceleration) is selected incorrectly.
The intensity of earthquake resistance must be determined according to the authority stipulated by the state. In general, the design is based on the fortification intensity, design basic seismic acceleration and design seismic grouping provided in Appendix A of the earthquake resistance specifications.
For cities that have prepared seismic fortification zones, seismic fortification can be carried out according to the approved seismic fortification intensity or designed seismic parameters. However, as towns expand, construction projects are becoming increasingly far away from the center of the town. Construction projects that are far away from the center of the town, especially construction projects that are in the direction of high fortification intensity, may require seismic fortification according to higher standards.
For example: Miyun, Huairou, Changping , Mentougou in Beijing. Appendix A of the "Seismic Anti-Seismic Specifications" gives 7 degrees (0.15g), but the four town centers may need to be fortified at 8 degrees (0.2g) towards the center of Beijing. Generally, these villages and towns that are seismically protected by higher standards are located within 4km areas on both sides of the earthquake peak acceleration dividing line.
"Construction Seismic Design Code" Article 1.0.4 .
11. There is a diagonal anti-lateral force member with an angle greater than 150, and the horizontal seismic effect calculation in the direction of the diagonal anti-lateral force member is not performed.
has a structure of oblique anti-lateral force members. Considering that earthquakes may come from any direction, it is required to calculate the horizontal seismic effect of the anti-lateral member direction with an intersection angle greater than 150. The computer results generally output the angle of the maximum seismic action direction. When its value is large, the seismic action calculation of the seismic action direction is not performed. Earthquake action is multidirectional, and there is always one direction with the greatest effect. When it is greater than 150, the maximum seismic effect calculation should be performed in this direction, and the construction drawings should be designed and drawn based on this larger calculation result.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.1 .
12. The large span and long cantilever structure with an intensity of 8 or 9 degrees of seismic protection have not been calculated vertical seismic. The large span and long cantilever structures in 7-degree (0.15g) high-rise buildings should also be calculated vertical seismic effects.
The vertical seismic action needs to be calculated. The conversion components of the conversion structure, the connecting body of the connecting structure when the seismic design is 7 degrees (0.15g) and 8 degrees, and the high-rise buildings when the seismic resistance is 9 degrees.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.1 .
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 Article 4.3.2, Section 10.5.2.
13. The structure self-vibration period used to calculate the seismic impact coefficient in structure does not consider the stiffness influence of the non-load-bearing wall to be reduced.
Considering the contribution of masonry filling walls to the lateral stiffness of the structure, the calculated self-vibration period must be reduced according to Article 4.3.17 of the High Regulations.
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 No. 4.3.16.
14. When evaluating earthquake resistance, the shear coefficient of any floor should comply with the requirements of Article 5.2.5 of the "Seismic Code". If multiple floors are not met, it is inappropriate to just adjust the minimum seismic shear coefficient of the floor.
If the shear coefficients on multiple floors are not satisfied, it means that the lateral stiffness of the structure is insufficient, and the lateral stiffness of the structural system should be increased.
should also be noted: when the bottom shear force is not much different, the multiplied by the increase coefficient can be used according to the specifications; when the bottom shear force is much different, the selection and overall layout of the structure need to be readjusted, and it cannot be processed by the multiplied by the increase coefficient.
For vertical irregular structures, the weak layer of the mutation site should also be multiplied by a coefficient not less than 1.15 according to Article 3.4.4 of the earthquake resistance specification.
"Construction Seismic Design Code" GB50011-2010 Article 5.2.5 .
15. The construction site category is incorrect. The calculation book and drawings are all Class 2 soil. The geological survey report is Class 2, and the structural calculation should be recalculated.
Site category is related to calculating the seismic impact coefficient of earthquake action. Incorrect site category will lead to incorrect seismic effect calculation.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.4 .
16. Single-story factory only considers horizontal horizontal seismic effects, but does not calculate horizontal seismic effects of the vertical direction of the factory.
Generally speaking, horizontal seismic action should be calculated separately in at least two main axial directions of the building structure, and horizontal seismic action in each direction should be borne by the lateral force-resistant components in that direction.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.1 .
17. The building structure with obviously asymmetric and uneven mass and stiffness distributions, and the torsional effect under the action of bidirectional horizontal earthquake was not calculated during seismic calculations.
"Structure with obviously asymmetric and uneven mass and stiffness distribution", generally refers to the ratio of the maximum displacement to the average displacement of the floor exceeds the lower limit of the displacement ratio of 1.2 under the assumption of rigid floor slabs, under the action of accidental eccentric one-way horizontal earthquakes and earthquakes.
calculates the bidirectional horizontal seismic effect and considers the torsional impact and calculates the one-way horizontal seismic effect and considers the accidental eccentric effect and takes the most adverse consideration. For multi-story buildings, any irregular multi-story buildings referred to in Article 3.4.2 of the earthquake resistance specification should also be considered as the influence of accidental eccentricity.
"Construction Seismic Design Code" GB50011-2010 Article 5.1.1 .
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 4.3.1 .
2. Foundation
1. Buildings with design grades A or Class B or non-embedded rock piles with design grades A and non-deep hard holding layer are considered to be deformed and verification based on pile test test results and design experience, so no settlement calculation results are provided.
Article 3.0.2, paragraphs 2 and 3 of the "Soil Code" have clear provisions on the scope of verification of building foundation deformation, and the design should be strictly followed. Experience cannot replace laws and regulations, settlement calculations should be carried out in accordance with regulations.
"Construction Foundation Design Code" GB50007-2011 Article 3.0.2 .
2. No safety requirements were put forward for foundation pit excavation.
should write specific requirements in the general structure description or foundation pit excavation diagram according to Article 9.1.9.
"Construction Foundation Design Code" GB50007-2011 No. 9.1.9.
3. Do not check whether the concrete strength of the pile body meets the pile test requirements. The concrete strength of the pile body should meet the pile bearing capacity design requirements.
"Construction Foundation Design Code" GB50007-2011 No. 8.5.10.
4. Buildings with a design level of Class B on composite foundations or weak foundations have no settlement observation points and no deformation observation requirements have been proposed (there are many such problems in 8th and 9th floor buildings).
buildings with a design level of Class B on composite foundations or weak foundations must undergo deformation observations during construction and use periods as required.
"Construction Foundation Design Code" GB50007-2011 No. 10.3.8.
5. The foundation groove (pit) inspection should be carried out after the foundation pit is excavated to the design elevation. After excavation of the foundation groove (pit), the foundation groove inspection should be carried out.Base groove inspection can be used for touch detection or other methods. When it is found that it is inconsistent with the survey report and design documents, or abnormal situations are encountered, handling opinions should be put forward in light of geological conditions.
"Construction Foundation Design Code" GB50007-2011 No. 10.2.1.
6. Considering geological conditions, "focus on monomers and neglects the environment", it is not considered that mountainous buildings and structures may suffer adverse effects such as landslides, collapses, mudslides, and heavy rainfall.
site selection and positioning are reasonably avoided, and the foundation and superstructure are appropriately strengthened. In areas affected by mountain torrents, corresponding flood discharge measures should be taken. Landslides that have development trends and threaten the safe use of buildings should be rectified as soon as possible to prevent the landslide from continuing to develop.
"Construction Foundation Design Code" GB50007-2011 Article 6.1.1, Article 6.1.4 .
7. Ignore the verification of the load bearing capacity and shear bearing capacity of the beam-slab-type raft base plate.
"Construction Foundation Design Code" GB50007-2011 Article 8.4.11 .
8. The thickness of the concrete structure at the deformation joint should not be less than 300mm.
Because the deformation joint is a weak link in waterproofing, especially when the medium-buried water stop is used, the water stop divides the concrete here into two parts, which will adversely affect the concrete at the deformation joint. Therefore, the regulations on local thickening of the concrete at the deformation joint.
"Technical Specifications for Waterproofing of Underground Engineering" GB 50108-2008 Article 5.1.3 .
9. Ignore the necessary deformation verification after foundation treatment; or replace the foundation deformation verification with the settlement estimate in the geological survey report.
The scope of deformation verification of the processed foundation is the same as that of the "Code for Design of Building Foundations" No. 3.0.2.
"Technical Specifications for Building Foundation Treatment" JGJ79-2002 Article 3.0.5 .
10. The construction quality inspection requirements for replacement cushion layer are unknown.
should be noted in the figure that the construction quality inspection of the cushion layer must be carried out in layers, and the layer of soil should be filled after the compaction coefficient of each layer meets the design requirements.
"Technical Specifications for Building Foundation Treatment" JGJ79-2002 Article 4.4.2 .
11, the quality inspection requirements for the construction of CFG pile composite foundation are inaccurate, and the characteristic value detection requirements for the bearing capacity of the composite foundation are proposed according to the modified bearing capacity characteristic value fa.
should provide inspection requirements according to the composite foundation bearing capacity characteristic value fspk before depth and width correction.
"Technical Specifications for Building Foundation Treatment" JGJ79-2002 Article 9.4.2 .
12. The general structure description of buildings on the wet loess site does not require use, maintenance and maintenance requirements.
should be noted in the design: During use, buildings and pipelines should be maintained and repaired regularly, and all waterproofing measures should be ensured to prevent water invasion and descent of the foundation of buildings and pipelines.
"Building Code for Sinking Loess Areas" GB50025-2004 Article 9.1.1 .
13. The pile foundation calculation book is not comprehensive. Such as calculation of the horizontal bearing capacity of pile foundation; calculation of the pull-out bearing capacity of anchor piles; calculation of the bearing capacity of pile body and bearing structure, etc.
should provide a calculation book according to the calculation items required by Article 3.1.3 of the Pile Foundation Specification to review whether the pile foundation design is safe and reasonable.
"Technical Specifications for Building Pile Foundations" JGJ 94-2008 Article 3.1.3 .
14. When the concrete strength level of the foundation (including the bearing) is less than the concrete strength level of the column or pile, the local pressure bearing capacity of the foundation is not verified.
local pressure bearing capacity verification is generally calculated according to Appendix D.5 of the local pressure concrete in " Concrete Structure Design Specification ". When the requirements are not met, the concrete strength level can be increased or the indirect steel bars (reinforced mesh or spiral reinforcement) can be used to calculate according to Section 6.6 of the "Concrete Code".
"Construction Foundation Design Code" GB50007-2011 Article 8.2.7, Article 8.4.18, Article 8.5.22 .
15. When calculating the foundation bearing capacity, the load effect standard combination was not used; when designing the foundation bearing capacity, the load effect basic combination was not used.
When verifying the foundation bearing capacity and foundation bearing capacity, different load effect combinations should be used respectively.
"Construction Foundation Design Code" GB50007-2011 Article 3.0.5 .
16. Buildings and structures built on slopes or near slopes have not been verified.
buildings and structures built on slopes or near slopes only verify the bearing capacity and deformation of the foundation and the slope stability verification is ignored, and the stability calculation should be carried out in accordance with the provisions of 5.4 of the "Structure Code".
"Construction Foundation Design Code" GB50007-2011 Article 3.0.2 .
17. When the load difference in the same structural unit is very large or is placed on an uneven soil layer, and there is ground loading on the foundation and near the ground, the foundation foundation design only meets the bearing capacity requirements and no foundation deformation calculation is performed.
should be checked for foundation settlement amount, settlement difference, inclination and local inclination according to Section 5.3 of the "Structure Code" respectively. The impact of settlement difference should be considered in the foundation and superstructure.
"Construction Foundation Design Code" GB50007-2011 Article 3.0.2 and Article 5.3.4 .
18. Design the overall foundation of the large chassis under the multi-tower and podium, and only the foundation settlement under the tower is calculated separately.
has multiple high-rise and low-rise buildings built on the same large area. The foundation deformation calculation should be carried out according to the superstructure, foundation and foundation joint action, which complies with Article 5.3.10 of the "Structure Code" and meets the requirements of Article 5.3.4 of the "Structure Code".
"Construction Foundation Design Code" GB50007-2011 Article 5.3.4 .
19. The foundation holding layer is set on the untreated liquefied soil layer;
Buildings built on the liquefied soil layer have many examples of foundation instability during earthquakes and buildings collapse or damage. The level of liquefaction is different, and the degree of earthquake damage is also different. For anti-liquefaction measures, see Articles 4.3.6~4.3.9 of the "Seismic Code".
"Construction Seismic Design Code" Article 4.3.2 .
20. The encryption range of pile stirrups does not meet the specification requirements.
pile stirrup should comply with the relevant provisions and requirements of Article 4.4.5 of the "Seismic Resistance Code" and Chapter 4 of the "Seismic Foundation Code".
"Construction Seismic Design Code" Article 4.4.5 .
21. When the groundwater level is high (groundwater is buried shallow), there is a problem of floating up the building's basement or underground structure, and no anti-float verification is carried out.
anti-floating stability verification is calculated according to Article 5.4.3 of the "Structure Foundation Specifications". Measures to increase structural stiffness can also be used when the overall requirements of anti-floating stability are met but locally not met.
drawing documents should also indicate the time for stopping precipitation during construction. It should also be noted that the anti-float design water level is different from the anti-water design water level.
"Construction Foundation Design Code" GB50007-2011 Article 3.0.2 .
3. Masonry
1. The number or height of the masonry structure exceeds the specification limit.
limit.
earthquake damage survey shows that the more floors and heights of masonry houses, the more serious the earthquake damage. The new seismic specification adds layer counts and height limits of 7 degrees (0.15 g) and 8 degrees (0.3 g).
Bottom Frame- Seismic Wall Masonry Houses are not allowed to be used in Class B buildings and Class C buildings of 8 degrees (0.3g). When
6 or 7 degrees, after taking strengthening measures in accordance with Article 7.3.14 of the earthquake resistance specification, the number and height of the floors will still be adopted according to the provisions of Table 7.1.2 of the earthquake resistance specification.
The total height of masonry houses with fewer horizontal walls is reduced by 3m according to the specification table 7.1.2, and the number of layers is reduced by one layer; there should be one layer when there are fewer horizontal walls. The new anti-regulation stipulates the meaning of "few horizontal walls" and "few horizontal walls".
For sloped roofs with attics, they should be calculated to be 1/2 of the height of the pointed wall. (a) The attic in the figure is not used as one floor, and its height is included in the height of the slope roof; (b) The attic in the figure is as one floor, and its height is included in the height of the slope roof; (c) The "small building" on the roof under the slope roof (the actual effective usable area or representative value of gravity load is less than 30% of the top floor) can not be included in the number of floors and height control range.
The total height of a house refers to the height from the outdoor floor to the main roof panel roof or eaves. The semi-basement starts from the indoor floor of the basement, and the entire basement and semi-basement with good embedded conditions should be allowed to start from the outdoor floor.Whether it is a full basement or a semi-basement, the seismic strength verification should be used as a first floor and meet the wall bearing capacity requirements.
"Construction Seismic Design Code" GB50011-2010 7.1.2 ;
" Masonry Structure Design Code " GB50003-2011 10.1.2 .
2. Bottom frame - seismic wall masonry house, the layout and quantity of bottom seismic walls do not meet the specification requirements.
Bottom frame - Seismic wall masonry house is an unfavorable architectural structure system. The upper and lower layers are composed of different materials, and the stiffness of the upper and lower layers is relatively different. This structure is economically adopted, but measures must be taken to ensure seismic safety.
Bottom frame - Seismic wall The maximum spacing of the seismic wall at the lower part of the masonry house exceeds the specification requirements.
The bottom seismic wall should be set in a certain number along the vertical and horizontal directions and arranged evenly and symmetrically. The ratio of the lateral stiffness of the second layer to the bottom layer should not be greater than 2.5 at 6 or 7 degrees, and should not be greater than 2.0 at 8 degrees, and should not be less than 1.0. The lateral stiffness ratio of the floor of the seismic wall brick masonry house does not meet the specification requirements; it is advisable to adjust the length of the seismic wall or open a hole in the seismic wall to adjust the lateral stiffness of the wall to meet the requirements.
specification stipulates that the bottom seismic wall bears all seismic force, and as a safety reserve, it also requires that the framework should also be designed to bear 20% of the seismic force.
"Construction Seismic Design Code" GB50011-2010 Articles 7.1.5, 7.1.8, and 7.2.4 .
3. The seismic structure of the masonry house supporting wall beam does not meet the requirements.
bottom frame seismic wall masonry house supporting wall beam is an extremely important component in this structure. The strength and stiffness of the supporting wall beam must be ensured. The specification stipulates that the cross-sectional width of the beam should not be less than 300mm, and the cross-sectional height of the beam should not be less than 1/10 of the span. This is to ensure the overall stiffness of the supporting wall beam.
In addition, considering the repetition of earthquake effects, it is also required that the stressed reinforcement and waist reinforcement should be anchored in the column according to the requirements of the tensioned reinforcement bar, and the anchoring length of the upper longitudinal reinforcement in the column should meet the relevant requirements of the reinforced concrete frame support beam; waist reinforcement should be installed along the beam height, the number should not be less than 2Ф14, and the spacing should not be greater than 200mm; the spacing should not be greater than 100mm in the encrypted area, and the diameter should not be less than 8mm. In addition to encrypting the static span of the beam at the end of the beam, the stirrup should also be encrypted within the range of 500mm at the opening of the upper wall and the sides of the opening of the hole.
"Construction Seismic Design Code" GB50011-2010 7.5.8.
4, bottom frame - seismic wall masonry house frame structure, the upper masonry seismic wall is aligned with the bottom frame beam or seismic wall, or basic alignment, and it is difficult to meet the specification requirements.
"Construction Seismic Design Code" GB50011-2010 7.1.8 items.
5. The adjustment coefficient γa of the masonry strength design value is ignored.
The adjustment coefficient of the masonry strength design value is related to the safety of the structure. The adjustment coefficient of the masonry strength design value mainly involves the area adjustment coefficient and the cement mortar adjustment coefficient. Tests show that medium and high-strength cement mortar has no adverse effect on the compressive strength of the masonry and the shear strength of the masonry. When cement mortar greater than M5 is used, the masonry strength can not be adjusted.
"Masonry Structure Design Code" GB50003-2011 Article 3.2.3 .
6. In the design of multi-layer masonry houses, the role of structural column as the main seismic structural measure is ignored, and structural columns are not set up according to the requirements of the specifications.
"Seismic Resistance Specifications" strengthens the seismic structural measures of stairwells. The structural columns added at the corresponding walls at the upper and lower ends of the stairwells have eight structural columns in total, and the structural columns set at the four corners of the stairwell, and then form an emergency evacuation safety island with the concrete reinforced belt set at half the height of the floor.
"Construction Seismic Design Code" GB50011-2010 Article 7.3.1 and Article 7.4.1 .
7. Reinforced concrete floor slabs are assembled integral floor slabs, and ring beams also mistakenly made prefabricated floor slabs; cast-in-place floor slabs may not be equipped with ring beams, but the floor slabs do not strengthen the steel bars along the periphery of the wall; prefabricated floor slabs only have peripheral ring beams on the exterior wall, and no ring beams on the inner wall.
ring beams can enhance the integrity of the house and improve the seismic resistance of the house. They are effective seismic resistance measures. The seismic ring beam must be cast in place.An example of prefabricated ring beam damage was found in earthquake areas. During earthquakes, the ring beam and the floor slab cannot be reliably bonded, and the ring beam will fall off the floor slab.
cast-in-place floor slabs have good integrity and high horizontal stiffness. Therefore, there is no need to set up another ring beam, but the general steel bars in the floor slab, including distributed steel bars, are not enough to form the frame function of the floor slab. Reinforced steel bars need to be installed and reliablely connected with the structural column steel bars.
Prefabricated floor slabs are only equipped with ring beams on the exterior walls. Longer exterior wall ring beams also need to be tied in the middle section. Seismic-resistant closed ring beams should be installed on the exterior wall, inner vertical wall, and inner horizontal walls according to the specifications. Article 7.3.3 of "Construction Seismic Design Code" GB50011-2010 .
8. As an earthquake-resistant safety island, no earthquake-resistant strengthening measures were taken.
also shows that the stairwell is often damaged seriously due to its relatively empty space, and a series of effective measures must be taken. Prefabricated stairs should not be used at 8 or 9 degrees. The buildings and elevators that protrude the roof are affected by major earthquakes during earthquakes, and the structural measures may be particularly strengthened.
"Construction Seismic Design Code" GB50011-2010 Article 7.3.8 .
9. In prefabricated floors, when there are cast-in-place ring beams, the length of the prefabricated boards extending into the wall does not meet the requirements; the house has a large open room (the opening is greater than 4.2m), and there is a lack of a tie between the building, roof and wall or beam.
The shelving length of the floor slab, the tie between the floor slab and the ring beam, the tie between the wall, the anchoring and tie between the roof slab (beam) and the columns, etc. are important measures to ensure the integrity of the building, the roof and the wall. When the ring beam is installed at the bottom of the plate, the reinforced concrete prefabricated plates should be tied to each other and should be tied to the beam, wall or ring beam. For detailed pictures, see Shaanxi 09G0901-1.
"Construction Seismic Design Code" GB50011-2010 Article 7.3.5 .
10. The roof beams and roof structures in the earthquake area did not take measures to strengthen their resistance.
"Construction Seismic Design Code" GB50011-2010 Article 7.3.6 .
11. In a multi-layer concrete small hollow block house, a structural column system can be used or a core column system can be used. The choice should be treated differently.
"Construction Seismic Design Code" GB50011-2010 Article 7.4.1 .
12. Bottom frame-seismic wall masonry house floor building seismic structural measures do not meet the requirements.
Bottom frame-seismic wall masonry house has different lateral force resistance structural systems from the upper layers. In order to make the floor cover have the stiffness to transmit horizontal seismic force, the bottom plate of the transition layer is required to be cast-in-place floor slabs with a thickness of not less than 120mm, and there should be few holes or small holes. When the hole size of the floor slab is greater than 800mm, side beams should be set up around the opening. The requirements for building buildings on each floor on the upper floor are the same as those for multi-story brick houses.
"Construction Seismic Design Code" GB50011-2010 Article 7.5.7 .
13. Bottom frame-seismic walls are installed on the bottom floor of the masonry house. The walls are built first and then beams and columns are poured as required.
Multi-story masonry houses should also be built first and then poured into structural columns during construction. Bottom frame-seismic wall masonry house floor is set up to constrain ordinary brick masonry or small block masonry seismic walls at 6 degrees and the number of floors of the house does not exceed 4 floors.
"Construction Seismic Design Code" GB50011-2010 Article 3.9.6, Article 7.1.8 .
4. Concrete structure
1, beams, columns, slabs, shear wall The minimum reinforcement rate of stressed steel bars and stirrups does not meet the requirements of the specifications; the reinforcement rate of longitudinal reinforcement of the converted beam is incorrectly designed according to the general frame beam requirements; the minimum total reinforcement rate of frame columns of high-rise buildings built on Class I site with a house height of more than 60m has not increased by 0.1%.
The minimum reinforcement rate does not meet the requirements of the specifications, especially the probability of fat beams, fat columns, thick walls and thick plates appearing.
conversion beams are different from general frame beams: conversion beams are generally eccentric tensioned components and withstand greater shear forces, while general frame beams are curved shear components; conversion beams have large internal forces, while general frame beams have relatively small internal forces; conversion beams have higher ductility requirements during seismic design.
"Concrete Structure Design Code" GB50010-2010 Article 8.5.1, Article 11.3.6, Article 11.4.12, Article 11.7.14 .
"Construction Seismic Design Code" GB50011-2010 Article 6.3.7 and Article 6.4.3 .
"Technical Regulations on Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.3.2, Article 6.4.3, Article 7.2.17, Article 8.2.1, Article 10.2.7, Article 10.2.10, Article 10.2.19 .
2. The seismic resistance level of concrete structure is selected incorrectly.
The seismic resistance level should be used according to the seismic fortification classification, intensity, and structural type of house height.
frame support shear wall structure, the seismic resistance level of the shear wall should be distinguished from the bottom reinforcement area (the key is the height of the frame support layer plus the two layers above the frame support layer) and the seismic resistance level of the non-reinforcement area. When the frame-shear wall is under the action of a specified horizontal force, and the seismic overturning moment borne by the bottom layer (calculate the layer where the embedded end is located) is greater than 50% of the total seismic overturning moment of the structure, the seismic resistance level of the frame should be determined according to the frame structure, and the seismic resistance level of the seismic wall can be the same as the frame's seismic resistance level.
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 3.9.3 .
"Concrete Structure Design Code" GB50010-2010 Article 11.1.3 .
"Construction Seismic Design Code" GB50011-2010 Article 6.1.2, Article 6.1.3.
3, frame beams and conversion beams do not have stirrup encryption areas; when there is a door hole on the upper wall of the conversion beam to form a small wall limb or a pillar on the beam, the stirrups of the conversion beams at this part are not encrypted.
When a multi-layer frame structure is installed with a pull beam layer near the ground below the outdoor ground, the seismic structural measures of the pull beam should also meet the requirements of the frame beam and a stirrup encryption area should be set up.
The bending moment and shear force of the conversion beam at the edge of the hole and the support column are greatly increased; during seismic design, the structure of the full-length stirrup along the connecting beam should be adopted according to the requirements of the frame beam encryption area, and the connecting beam should not be encrypted according to the general frame beam only at a certain range of stirrups at the end of the beam.
"Construction Seismic Design Code" GB50011-2010 ;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.3.2 and Article 10.2.7 .
4. The computer calculation diagram does not match the actual construction drawings, such as the layout and quantity of shear walls, concrete strength grade, beam cross-sectional dimensions, etc.
The calculation sketch does not match the actual construction drawings, which will bring hidden dangers to structural safety. The structural major must cooperate closely with each major and modify the main calculations in a timely manner to ensure that the calculation sketch is consistent with the actual construction drawings.
"Construction Seismic Design Code" GB50011-2010 Article 3.5.2 and Article 3.6.6 .
5. The guarantee rate of the standard value of steel bar strength is not indicated; the special requirements for material and construction quality of seismic structures are not indicated.
In the concrete structure design description, it should be proposed that when the frame and oblique brace components (including stairs) with earthquake resistance levels of one, two or three, and their longitudinal bars are made of ordinary steel bars, the actual measured value of the tensile strength of the steel bar and the actual measured value of the yield strength should not be less than 1.25; the ratio of the actual measured value of the yield strength of the steel bar and the standard value of the yield strength should not be greater than 1.3, and the total elongation of the steel bar under the maximum tensile force should not be less than 9%.
The standard value of reinforcement strength should have a guarantee rate of no less than 95%.
"Construction Seismic Design Code" GB50011-2010 Article 3.9.1 and Article 3.9.2 .
"Concrete Structure Design Code" GB50010-2010 Article 4.2.2 .
6. The seismic fortification classification of building is not correctly determined.
For example: high-rise buildings with large chassis, when the bottom several floors are large supermarkets and meet the standards of large shopping malls, the seismic fortification category has not been designated as the key fortification category (Class B); or the entire building is designated as the Class B; or even if the lower several floors are commercial buildings but do not meet the standards of large shopping malls, they are designated as the key fortification category.
"Classification Standard for Seismic Fortification of Construction Engineering" GB50223-2008 Article 3.0.1 .
"Classification Standard for Seismic Fortification of Construction Engineering" GB50223-2008 Article 3.0.2 .
"Construction Seismic Design Code" GB50011-2010 Article 3.1.1 .
7. The horizontal distribution ribs of the exterior wall of the civil defense basement do not meet the minimum reinforcement rate requirements.
The reinforcement ratio of components with protection requirements is different from that of general components, and should be treated differently during design.
"Civil Air Defense Basement Design Code" GB50038-2005 Article 4.11.7 .
8. During seismic design, the ratio of the bottom reinforcement and the top reinforcement of the end section of the first-level frame beam is less than 0.5, and the second and third-levels are less than 0.3.
level one should be greater than 0.5; levels two and three should be greater than 0.3. The ratio of longitudinal steel bars on the end of the beam and the top surface of the beam has a great impact on the deformation ability of the beam, and can prevent premature yield or serious damage when the positive bending moment appears at the bottom of the beam in an earthquake, thereby affecting the normal performance of bearing capacity and deformation ability.
"Construction Seismic Design Code" GB50011-2010 Article 6.3.3 ;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.3.2 .
9. During seismic design, the reinforcement ratio of longitudinal reinforcement at the end of the frame beam is greater than 2%, but the minimum diameter of stirrups in the end of the beam is not increased by 2mm.
test and earthquake damage show that the damage at the end of the beam is mainly concentrated within the beam height range of 1.5 to 2 times. It is possible to obtain better ductility by limiting the length of the stirrup enlargement area of the beam end, the maximum spacing and minimum diameter of the stirrups. When the reinforcement ratio of the longitudinal reinforcement bar at the end of the frame beam is greater than 2%, the requirements for stirrups are also increased accordingly.
The cantilever sections of the cantilever beam and frame beam do not perform this as the stirrups. For the inner span adjacent to the beam cantilever section, it is recommended to determine the diameter of the stirrup according to whether the gluten of the cantilever support exceeds 2%.
"Construction Seismic Design Code" GB50011-2010 Article 6.3.3 ;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.3.2 .
10. When the first-level earthquake resistance level is used, when the frame beam and column longitudinal bars use steel bars of diameter 16 or 14, if the spacing between stirrups is matched to @100 does not meet the requirements of 6d; when the height of the frame beam is 300, the spacing between stirrups is 100 greater than 1/4 of the beam height, 75 should be taken.
test and earthquake damage show that when the spacing between stirrups is less than 6d to 8d, the compressed steel bars before concrete collapse generally do not cause compression and have better ductility.
"Construction Seismic Design Code" GB50011-2010 Article 6.3.7; Article 6.3.3 .
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 Article 6.4.3, Article 6.3.2 . At the base of the third and fourth-level frame columns, the spacing between stirrups in the encryption area is 150 less than 100 and 8d (d is the diameter of the longitudinal stressed steel bar ).
The spacing of stirrups at the root of the third and fourth-level frame column columns (lower end of the bottom column) should be the smaller values of 100 and d (d is the diameter of the longitudinal stressed steel bar).
"Construction Seismic Design Code" GB50011-2010 Article 6.3.7 ;
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3-2010 Article 6.4.3 .
12. During seismic design, no provisions were made on the principle of substitution for longitudinal stressed steel bars in the main structure.
If the principle of substitution of longitudinal stressed steel bars in the main structure is not specified, the total bearing capacity of the replaced longitudinal stressed steel bars will often be greater than the design value of the total bearing capacity of the original design of the longitudinal stressed steel bars, thereby causing the transfer of seismic weak parts, and may also cause concrete brittle damage (concrete crushing, component shear failure) in the affected parts of the components. When replacing longitudinal stressed steel bars, they should be converted according to the principle of equal tensile bearing capacity of the steel bars, and meet the requirements of normal use limit state (cracks, deflection) and seismic structural measures (maximum and minimum reinforcement ratio, protective layer thickness, steel bar spacing, etc.). In particular, when replacing the original design longitudinal stressed steel bars with higher grades, attention should be paid to the impact of changes in the steel bar ductility (strong curve ratio, plastic design conditions, etc.) caused by the above substitution.
"Construction Seismic Design Code" GB50011-2010 Article 3.9.4 .
13. When designing the frame structure, the form of a mixed load bearing of the frame and some masonry walls should not be adopted.
Not only should a frame structure house not be partially masonry-bearing, but the elevator room, elevator machine room, stairwell, water tank room, etc. in the frame structure, should not be load-bearing with masonry walls, but frame load-bearing, and non-load-bearing filling walls should be used. Frame structure and masonry structure are two completely different structural systems. The earthquake damage shows that if used in the same building, masonry walls with lateral stiffness far greater than those of the frame during earthquake will first be damaged, resulting in a sharp increase in the internal force of the frame, and then the frame is damaged or even collapsed.
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 Article 6.1.6 .
14. The waist reinforcement of the conversion beam is less than 2Ф16@200; the negative reinforcement of the conversion beam support is configured according to the general frame beam, and the beam surface pulling rib is less than 50% of the total gluten area.
conversion beam is an eccentric tensioned component and should be designed according to the actual situation of the project. When the reinforcement calculation is controlled by the combination of positive bending moment and tensile force in the middle span, at least 50% of the longitudinal stressed steel bars in the upper longitudinal part of the support are penetrated along the full length of the beam; when the reinforcement calculation is controlled by the comprehensive control of negative bending moment and tensile force in the support, all the longitudinal bars in the upper support should be penetrated along the full length; all the longitudinal bars in the lower longitudinal bars should be passed through directly into the column.
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 Article 10.2.7 .
15. When there is a disassembled structure in a high-rise building, the cross-sectional height of the frame column at the disassembled layer should not be less than 600mm, the concrete strength level should not be less than C30, the seismic resistance level should be increased by one level, and the stirrups should be encrypted in the entire column section.
The dislocation structure is a vertical irregular structure. The vertical lateral force-resistant components near the dislocation layer are complicated to bear the stress. The dislocation structure often forms many irregular structures in which short columns and long columns are mixed. Therefore, strengthening measures should be taken for components of the severed structure at the severed layer. If the concrete components at the disassembled layer cannot meet the design requirements, effective measures need to be taken, such as the frame column using steel concrete columns or steel pipe concrete columns; the shear wall is equipped with steel in the shear wall to improve the seismic performance measures of the components.
"Technical Regulations for Concrete Structures of High-rise Buildings" JGJ3—2010 Article 10.4.4 .
16. The design file does not indicate the purpose of the structure.
Changes to the structure's purpose and usage environment (such as overloading use, structural hole opening, changing usage functions, and deteriorating usage environment) will affect the safety and service life of the structure. Any changes to the structure (whether under construction or existing structure) must be subject to design permission or technical appraisal to ensure the safety and function of the structure during its design service life.
Seismic identification should be carried out before seismic reinforcement of existing building structures.
When the existing building is directly added to the floor, the existing building structure should be identified first.
"Concrete Structure Design Code" GB50010-2010 No. 3.1.7.
"Technical Regulations on Seismic Reinforcement of Buildings" JGJ116-2009 Article 3.0.1 .
"Technical Specifications for Reinforcement of Foundations of Existing Buildings" JGJ123-2000 Article 8.1.1 .
1. In steel structure design, the general design description does not indicate the steel grade, connecting material model (or steel number), the mechanical properties, chemical composition of the steel, etc. In addition, the required welds, weld quality grades and construction requirements should also be noted.
and construction requirements.
These matters are closely related to ensuring the quality of the project. The grade of steel should be consistent with the current national standards or other technical standards of the steel; for the performance requirements of steel, all items that can be guaranteed by each grade in my country's steel standards can no longer be listed, and only items required by additional guarantees and agreements are mentioned. When other steel or foreign steels that do not form technical standards are used, various requirements for the performance of the steel must be listed in order to be inspected according to this. The quality grade of welds should be selected according to the importance of the components and the stress conditions in accordance with Article 7.1.1 of the "Steel Structure Code". Other requirements for the protection and insulation measures of the structure should be explained in the design documents.
" Steel Structure Design Specification " GB50017-2003 1.0.5 .
2. The seismically designed load-bearing steel structure has not provided supplementary material performance requirements for the steel material. It is only stated in the design documents that Q235 steel or Q345 steel are used; the welded load-bearing structure is incorrectly used Q235-A steel.
"Seismic Code" puts forward special minimum requirements for seismic steel structure steel, namely, actual measured strength curve ratio, elongation, impact toughness, yield step and weldability, and is indicated in the design document. Grade A steel does not guarantee impact toughness and the carbon content of Q235 steel is not used as a delivery condition, so it cannot be used in seismic fortification steel structures and welded load-bearing structures.
"Construction Seismic Design Code" GB50011-2010 Article 3.9.1 and Article 3.9.2 .
"Steel Structure Design Code" GB50017-2003 Article 3.3.3 .
3. In the steel structure design, the parts of the column feet below the ground should be wrapped with concrete with a lower strength grade.
investigation found that if any steel column buried in the soil has not extended out of the ground, or if the elevation of the base of the column foot is the same, moisture, dust and other debris are likely to accumulate around the contact part of the column body (or pillar foot) and the ground (or soil), causing severe rust. Although the steel columns buried in the soil in some chemical plants are wrapped in concrete, the rust is very serious due to ion polarization. Therefore, the pillar feet should not be buried underground under the conditions of erosion medium in the soil.
"Steel Structure Design Code" 8.9.3 in GB50017-2003.
4. The earthquake resistance level of the steel structure is not indicated.
2001's edition of the "Seismic Code" does not stipulate the seismic resistance level of steel structures. The 2010 version of the "Seismic Code" adjusts, summarizes and organizes the "effect adjustment" and "seismic structural measures" stipulated by the 2001's earthquake resistance specifications into four different requirements: "effect adjustment" and "seismic structural measures" stipulated in different intensity, different number of layers, and different seismic defense classifications, which are called seismic resistance levels.
"Construction Seismic Design Code" GB50011-2010 Article 8.1.3 .
5. The fire resistance level and fire resistance limit of the steel structure are not indicated.
Steel structure is relatively sensitive to temperature, and the steel structure without any protection has a fire resistance limit of only 0.25h. Article 8.9.4 of the "Steel Structure Design Code" GB50017-2003 stipulates that the fire protection of steel structures should comply with the requirements of the "Building Design Fire Protection Code" GB50016 and the "High-rise Civil Building Design Fire Protection Code" GB50045. The fire protection layer of structural components should be designed according to the fire protection level of the building. The performance, coating thickness and quality requirements of fire-retardant coatings should comply with the current national standards "Steel Structure Fire Retardant Coatings" GB14907 and "Technical Specifications for Application of Steel Structure Fire Retardant Coatings" CECS24. When the anti-rust primer and fire-resistant coating are used at the same time, it should be noted that the two must match. The surface of the steel that needs to be fire-resistant coating can be removed and only the primer coating can be used.
"Fire Protection Code for Building Design" GB50016-2006 Article 5.1.1 and Article 5.1.7 .
"Fire Protection Code for High-rise Civil Building Design" GB50045 Article 3.0.2 .
6. In the calculation of steel structure components, the design strength values of t=16 and t=20 are different, and no attention is paid to it, resulting in errors.
The design value of steel strength should be adopted according to the thickness or diameter of the steel plate according to Table 3.4.1-1 of the "Steel Structure Specifications". Thickness refers to the thickness of the steel material at the calculated point, and the thickness of the thicker plate parts in the cross section for the axial tension and the axial compression members.
"Steel Structure Design Code" GB50017-2003 Article 3.4.1 .
7. When calculating the strength of axial compressed single-angle steel and single-sided welding butt welds without pads, the strength design value is not multiplied by the reduction coefficient.
The compressed single-angle steel connected on one side is actually a bidirectional bending member, and the reduction coefficient should be used to consider the influence of bidirectional bending.
single-sided welding without padding, the weld cannot guarantee the full thickness of the welded parts, and the strength design value must be reduced.
"Steel Structure Design Code" GB50017-2003 Article 3.4.2.
8. No measures to prevent the nut from loosening when the ordinary bolt is directly subjected to the power load, or damage measures such as disrupting the thread are used.
In the design, the ordinary bolts cannot be confused with the power and the static load. In use, the bolts are tensed and subjected to dynamic loads, so the nuts are easily loosened or even slide down, leaving hidden dangers to structural safety. Anti-loosening measures should be taken for the nuts according to the steel structure specifications, such as using double nuts, spring washers or welding the nuts and screws to the dead.
"Steel Structure Design Code" GB50017-2003 Article 8.3.6
9. In cold-bent thin-walled steel structures, when designing the roof structure, the adverse effects of the roof wind suction effect caused by changes in the internal force of the component are not considered.
roof structure calculations are generally based on vertical loads, and the pressure and tension internal forces of each rod are calculated, and the cross-sections are selected, but various unfavorable load combinations should be considered. For light roof cold-bending thin-walled steel structures, due to the large body shape coefficient of wind suction, the internal force value and direction of the rod are often changed. If the value increases or changes from a tie rod to a press rod, the rod member should be designed according to the most unfavorable combination.
In addition, when designing rigid frames, purlins and wall beams, the adverse effects of roof wind suction should also be considered. At this time, the permanent load sub-coefficient should be taken as 1.0.
"Technical Specifications for Cold-bent Thin-Walled Steel Structures" GB50018-2002 Article 4.1.7 .
10. The roof does not have a complete support system. When the horizontal support of the roof is made of round steel, there is no tensioning device. In the temperature section of the house, no support system can independently form a spatially stable structure.
In order to ensure the spatial work of the roof structure, improve its overall stiffness, bear or transmit horizontal forces, avoid lateral instability of the pressure rod, and ensure the stability of the roof during installation and use, reliable support systems such as horizontal horizontal support, longitudinal horizontal support, vertical support, and tie rod should be set up according to the different conditions of the roof span and load. The support members should be self-organized. If the purlin is used as a support tray, the bending member should be designed.
Since the round steel is not controlled by the length and thin ratio, the appearance is small, the deflection value generated by the self-weight is relatively large, it is easy to sag and relax, and cannot effectively act as tensioning. It must have a tensioning device, and can be tensioned at both ends or tensioned at the middle basket.
"Steel Structure Design Code" GB50017-2003 Article 8.1.4 .
"Technical Specifications for Cold-bent Thin-Walled Steel Structures" GB50018-2002 Article 9.2.2, Article 10.2.3 .
11. End plates connected with rigid beams and columns with high-strength bolts do not meet the minimum thickness of 16mm.
Rigid beams and columns are usually designed according to rigid connection nodes. To ensure that the connection nodes are in line with the calculation model and the force transmission is reliable, in addition to meeting the calculation requirements, the end plate thickness must be strictly controlled to be no less than 16mm to ensure that the end plate has sufficient stiffness. In engineering practice, the thickness of the end plate should not be less than the diameter d of the high-strength bolt used at the node.
"Technical Regulations on Steel Structure of Gate-type Rigid Frame Lightweight Houses" CECS102-2002 Article 7.2.9 .
12. The upward pulling force of the anchor bolt with intercolumn support under wind load has not been reviewed.
The wind load on the end wall of the door type rigid frame (gable) is transmitted to the column support through structural components such as wind-resistant columns and horizontal roof support. The maximum vertical component of the column support is the upper pulling force generated by the column foot anchor connected to it.
According to Article 7.2.19 of the "Gateway Firm Rules", calculate the upward pulling force of the column foot anchor bolt supported between columns under the action of wind load. The maximum vertical component force generated by the support between columns should be included, and the influence of live load (or snow load), gray load and additional load should be 1.0.
When calculating the tensile bearing capacity of the column foot anchor bolt, the tensile strength design value of the Q235 steel anchor bolt is fat=140N/m㎡, and the tensile strength design value of the Q345 steel anchor bolt is fat=180N/m㎡, and the area of the anchor bolt is taken as the effective cross-sectional area at the thread.
"Technical Regulations on Steel Structure of Gate-type Rigid Frame Lightweight Houses" CECS102-2002 Article 7.2.19 .
13. The length and thin ratio of the frame column of the earthquake-resistant steel structure is accidentally controlled according to the specifications of ordinary steel structures.
The provisions for allowing length and thinness of components are mainly to avoid excessive flexibility of the components, excessive deflection under the action of its own gravity, causing the components to bend during transportation, installation, and prevent bending under vertical earthquakes during large earthquakes.
According to Articles 5.3.8 and 5.3.9 of the "Steel Structure Code", it can be seen that the adverse effects of insufficient stiffness are far more serious than those of the pressing rod. Comparing Article 8.3.1 of the "Seismic Code" and Article 5.3.8 of the "Steel Structure Code", it can be seen that the length and thinness limit of the seismic frame column is stricter than that of ordinary steel structures. The length and thinness ratio of the frame columns is related to the overall stability of the steel structure. Research shows that the height of the steel structure increases and the axial force increases, and vertical earthquakes have a great impact on the frame column. The higher the seismic resistance level, the stricter the length and thinness limit of the frame column. In addition, the length and thinness limit of the frame column is also related to the steel grade (yield strength). The length and thinness limit of the Q235 steel frame column is larger than the length and thinness limit of the Q345 steel, and the requirements are loose.
"Construction Seismic Design Code" GB50011-2010 Article 8.3.1 .
14. The seismic fortification frame, the length and thin ratio of the central support and the width and thickness ratio of the plate do not comply with the specifications.The main function of the central support of the frame is to reduce interlayer displacement and ensure overall stability of the structure. Under the action of earthquakes, the restorative force characteristics of the frame support system mainly depend on the compression behavior of the support rod. The length and thinness of the support are larger than that of the support, the hysteresis circle is smaller and the ability to absorb energy is weak. The length and thin ratio of the support rod should be designed according to the earthquake resistance level according to the earthquake resistance specifications.
limits the width-thickness ratio of the central support plate to prevent local instability of the plate. The central support inclined rod should adopt a biaxial symmetric cross-section. If a uniaxial symmetric cross-section is used, effective structural measures should be taken to prevent buckling about the axis of symmetry. As shown in the figure below, add re-dividing rods and other measures to support the herringbone oblique rod.
"Construction Seismic Design Code" GB50011-2010 Article 8.4.1 .
15. The width-thickness ratio of the flange plates of the eccentric support energy-saving beam section and the non-energy-saving beam section of the same span exceeds the limit specified in the specification.
limit value energy dissipation beam section width-thickness ratio is mainly to ensure that the energy dissipation beam section has good ductility and energy consumption capacity, so it is stricter than ordinary beams. In addition, the steel of the energy-saving beam section should be Q235, Q345, Q345GJ. When the upper flange of the beam is fixed to the floor slab but does not indicate that its lower flange is fixed sideways, lateral support is still required.
"Construction Seismic Design Code" GB50011-2010 Article 8.5.1 .
16. When the beam and the column are rigidly connected, the column is within 500mm of each upper and lower edges of the beam. The connection weld between the column flange and the web or box column wall panels does not use fully melted bevel welds according to the specifications.
Under the action of a rare earthquake, the frame nodes will enter the plastic zone. In order to ensure the integrity of the structure in the plastic zone, the column is placed within 500mm each upper and lower edges of the beam. The connection weld between the column flange and the web or box column wall plate adopts a fully melted bevel weld.
"Construction Seismic Design Code" GB50011-2010 Article 8.3.6 .
17. The column foot of the high-rise steel structure frame column does not use rigid column foot.
exposed column foot is generally a hinged column foot, usually used for axial compression column. For the connection between high-rise steel structure frame columns and foundations, rigid column feet are generally used. Rigid column feet are divided into embedded column feet and outsourcing column feet. Rigid column feet generally have M, N, and V forces. The Hanshin earthquake in Japan showed that exposed column feet were seriously damaged, and buried column feet should be used in high-rise steel structures.
"Technical Regulations for Steel Structures for High-rise Civil Buildings" JGJ99-98 Article 8.6.2 .
18. The fire resistance limit of the floor slab was determined to be 1.5h. No protective measures were taken in the pressed steel plate. The concrete above the top of the ribs of the pressed steel plate is still 50mm, but does not meet the fire protection requirements specified in the regulations. The fire resistance design of the structure should first determine the fire resistance level of the building, and then determine the fire resistance limit based on the fire resistance level, and then take protective measures. When pressed steel plates are used as load-bearing structures, fire protection design should be paid attention to.
"Technical Regulations for Steel Structures for High-rise Civil Buildings" JGJ99-98 Article 7.4.6 .
6, other
1, the design service life of the structure is not indicated.
Design service life is the period when the structure or structural components specified in the design can be used for their intended purpose without overhaul. It is clarified that the design service life is a period specified in the design. During this specified period, only normal maintenance is required without overhauling, and the predetermined function can be used as expected, namely the service life that the house should achieve under normal design, normal construction, normal use and maintenance. The so-called "normal maintenance" includes necessary inspection, protection and repair. The design service life is the concretization of the "reasonable service life" of the foundation engineering and the main structure engineering of the house building. The design benchmark period is the time parameter selected to determine the values of variable effects and time-related material properties, and it is not equivalent to the design service life of the building structure. The load statistical parameters are generally determined based on the design base period of 50 years. The actual life of a house is also different from the design service life. The house can continue to be used after being identified and reinforced after being approved.
"Unified Standard for Building Structure Reliability Design" GB50068-2001 Article 1.0.5 .
2. The security level of the structure is not indicated.
is divided into three safety levels according to the severity of the consequences of the damage of the building structure. Among them, a large number of general buildings are included in the intermediate levels, and important buildings are raised one level; secondary buildings are lowered one level. As for the division of important buildings and secondary buildings, it should be determined based on the consequences of the damage of the building structure, that is, the severity of endangering human lives, causing economic losses, and causing social impacts.
"Unified Standard for Building Structure Reliability Design" GB50068-2001 Article 1.0.8 .
3. The project design is carried out based on the survey results documents (such as foundation processing plan, foundation selection, ground endurance, etc.).
has insufficient understanding of the authoritative nature of the survey report. When there is any doubt, you should communicate with the survey unit. After the two parties reach an agreement, the survey unit should issue a supplementary survey report as the basis for design.
Article 40 of the "Regulations on Survey and Design Management of Construction Engineering" If one of the following acts violates the provisions of this Regulation and commits any of the following acts, it shall be punished in accordance with Article 63 of the "Regulations on Quality Management of Construction Engineering":
(1) The survey unit conducts survey according to the mandatory standards for engineering construction;
(2) The design unit conducts engineering design based on the survey results documents;
(3) The design unit specifies the manufacturer and supplier of building materials and building components;
(4) The design unit fails to design according to the mandatory standards for engineering construction.
1. The value of the protective layer of the steel bar is incorrect (mainly the protective layer of the waterproof concrete in the basement, the protective layer of the steel bar when the low-grade concrete is used, and the steel bar protective layer of the column).
2. The cracks in the basement waterproof concrete do not meet the requirements of 0.2mm.
3. Frame-support shear wall structure, the seismic resistance level of the shear wall is not distinguished from the bottom reinforcement area (the key is the height of the frame-support layer plus the height of the two layers above the frame-support layer) and the non-reinforcement area.
4. The height and thickness ratio of masonry does not meet the specification requirements.
5. The layout of the structural column does not meet the requirements of the specifications (mainly on both sides of the large hole).
6. Calculation of basement exterior wall strength, load sub-coefficient did not take into account.
investigation found that if any steel column buried in the soil has not extended out of the ground, or if the elevation of the base of the column foot is the same, moisture, dust and other debris are likely to accumulate around the contact part of the column body (or pillar foot) and the ground (or soil), causing severe rust. Although the steel columns buried in the soil in some chemical plants are wrapped in concrete, the rust is very serious due to ion polarization. Therefore, the pillar feet should not be buried underground under the conditions of erosion medium in the soil.
"Steel Structure Design Code" 8.9.3 in GB50017-2003.
4. The earthquake resistance level of the steel structure is not indicated.
2001's edition of the "Seismic Code" does not stipulate the seismic resistance level of steel structures. The 2010 version of the "Seismic Code" adjusts, summarizes and organizes the "effect adjustment" and "seismic structural measures" stipulated by the 2001's earthquake resistance specifications into four different requirements: "effect adjustment" and "seismic structural measures" stipulated in different intensity, different number of layers, and different seismic defense classifications, which are called seismic resistance levels.
"Construction Seismic Design Code" GB50011-2010 Article 8.1.3 .
5. The fire resistance level and fire resistance limit of the steel structure are not indicated.
Steel structure is relatively sensitive to temperature, and the steel structure without any protection has a fire resistance limit of only 0.25h. Article 8.9.4 of the "Steel Structure Design Code" GB50017-2003 stipulates that the fire protection of steel structures should comply with the requirements of the "Building Design Fire Protection Code" GB50016 and the "High-rise Civil Building Design Fire Protection Code" GB50045. The fire protection layer of structural components should be designed according to the fire protection level of the building. The performance, coating thickness and quality requirements of fire-retardant coatings should comply with the current national standards "Steel Structure Fire Retardant Coatings" GB14907 and "Technical Specifications for Application of Steel Structure Fire Retardant Coatings" CECS24. When the anti-rust primer and fire-resistant coating are used at the same time, it should be noted that the two must match. The surface of the steel that needs to be fire-resistant coating can be removed and only the primer coating can be used.
"Fire Protection Code for Building Design" GB50016-2006 Article 5.1.1 and Article 5.1.7 .
"Fire Protection Code for High-rise Civil Building Design" GB50045 Article 3.0.2 .
6. In the calculation of steel structure components, the design strength values of t=16 and t=20 are different, and no attention is paid to it, resulting in errors.
The design value of steel strength should be adopted according to the thickness or diameter of the steel plate according to Table 3.4.1-1 of the "Steel Structure Specifications". Thickness refers to the thickness of the steel material at the calculated point, and the thickness of the thicker plate parts in the cross section for the axial tension and the axial compression members.
"Steel Structure Design Code" GB50017-2003 Article 3.4.1 .
7. When calculating the strength of axial compressed single-angle steel and single-sided welding butt welds without pads, the strength design value is not multiplied by the reduction coefficient.
The compressed single-angle steel connected on one side is actually a bidirectional bending member, and the reduction coefficient should be used to consider the influence of bidirectional bending.
single-sided welding without padding, the weld cannot guarantee the full thickness of the welded parts, and the strength design value must be reduced.
"Steel Structure Design Code" GB50017-2003 Article 3.4.2.
8. No measures to prevent the nut from loosening when the ordinary bolt is directly subjected to the power load, or damage measures such as disrupting the thread are used.
In the design, the ordinary bolts cannot be confused with the power and the static load. In use, the bolts are tensed and subjected to dynamic loads, so the nuts are easily loosened or even slide down, leaving hidden dangers to structural safety. Anti-loosening measures should be taken for the nuts according to the steel structure specifications, such as using double nuts, spring washers or welding the nuts and screws to the dead.
"Steel Structure Design Code" GB50017-2003 Article 8.3.6
9. In cold-bent thin-walled steel structures, when designing the roof structure, the adverse effects of the roof wind suction effect caused by changes in the internal force of the component are not considered.
roof structure calculations are generally based on vertical loads, and the pressure and tension internal forces of each rod are calculated, and the cross-sections are selected, but various unfavorable load combinations should be considered. For light roof cold-bending thin-walled steel structures, due to the large body shape coefficient of wind suction, the internal force value and direction of the rod are often changed. If the value increases or changes from a tie rod to a press rod, the rod member should be designed according to the most unfavorable combination.
In addition, when designing rigid frames, purlins and wall beams, the adverse effects of roof wind suction should also be considered. At this time, the permanent load sub-coefficient should be taken as 1.0.
"Technical Specifications for Cold-bent Thin-Walled Steel Structures" GB50018-2002 Article 4.1.7 .
10. The roof does not have a complete support system. When the horizontal support of the roof is made of round steel, there is no tensioning device. In the temperature section of the house, no support system can independently form a spatially stable structure.
In order to ensure the spatial work of the roof structure, improve its overall stiffness, bear or transmit horizontal forces, avoid lateral instability of the pressure rod, and ensure the stability of the roof during installation and use, reliable support systems such as horizontal horizontal support, longitudinal horizontal support, vertical support, and tie rod should be set up according to the different conditions of the roof span and load. The support members should be self-organized. If the purlin is used as a support tray, the bending member should be designed.
Since the round steel is not controlled by the length and thin ratio, the appearance is small, the deflection value generated by the self-weight is relatively large, it is easy to sag and relax, and cannot effectively act as tensioning. It must have a tensioning device, and can be tensioned at both ends or tensioned at the middle basket.
"Steel Structure Design Code" GB50017-2003 Article 8.1.4 .
"Technical Specifications for Cold-bent Thin-Walled Steel Structures" GB50018-2002 Article 9.2.2, Article 10.2.3 .
11. End plates connected with rigid beams and columns with high-strength bolts do not meet the minimum thickness of 16mm.
Rigid beams and columns are usually designed according to rigid connection nodes. To ensure that the connection nodes are in line with the calculation model and the force transmission is reliable, in addition to meeting the calculation requirements, the end plate thickness must be strictly controlled to be no less than 16mm to ensure that the end plate has sufficient stiffness. In engineering practice, the thickness of the end plate should not be less than the diameter d of the high-strength bolt used at the node.
"Technical Regulations on Steel Structure of Gate-type Rigid Frame Lightweight Houses" CECS102-2002 Article 7.2.9 .
12. The upward pulling force of the anchor bolt with intercolumn support under wind load has not been reviewed.
The wind load on the end wall of the door type rigid frame (gable) is transmitted to the column support through structural components such as wind-resistant columns and horizontal roof support. The maximum vertical component of the column support is the upper pulling force generated by the column foot anchor connected to it.
According to Article 7.2.19 of the "Gateway Firm Rules", calculate the upward pulling force of the column foot anchor bolt supported between columns under the action of wind load. The maximum vertical component force generated by the support between columns should be included, and the influence of live load (or snow load), gray load and additional load should be 1.0.
When calculating the tensile bearing capacity of the column foot anchor bolt, the tensile strength design value of the Q235 steel anchor bolt is fat=140N/m㎡, and the tensile strength design value of the Q345 steel anchor bolt is fat=180N/m㎡, and the area of the anchor bolt is taken as the effective cross-sectional area at the thread.
"Technical Regulations on Steel Structure of Gate-type Rigid Frame Lightweight Houses" CECS102-2002 Article 7.2.19 .
13. The length and thin ratio of the frame column of the earthquake-resistant steel structure is accidentally controlled according to the specifications of ordinary steel structures.
The provisions for allowing length and thinness of components are mainly to avoid excessive flexibility of the components, excessive deflection under the action of its own gravity, causing the components to bend during transportation, installation, and prevent bending under vertical earthquakes during large earthquakes.
According to Articles 5.3.8 and 5.3.9 of the "Steel Structure Code", it can be seen that the adverse effects of insufficient stiffness are far more serious than those of the pressing rod. Comparing Article 8.3.1 of the "Seismic Code" and Article 5.3.8 of the "Steel Structure Code", it can be seen that the length and thinness limit of the seismic frame column is stricter than that of ordinary steel structures. The length and thinness ratio of the frame columns is related to the overall stability of the steel structure. Research shows that the height of the steel structure increases and the axial force increases, and vertical earthquakes have a great impact on the frame column. The higher the seismic resistance level, the stricter the length and thinness limit of the frame column. In addition, the length and thinness limit of the frame column is also related to the steel grade (yield strength). The length and thinness limit of the Q235 steel frame column is larger than the length and thinness limit of the Q345 steel, and the requirements are loose.
"Construction Seismic Design Code" GB50011-2010 Article 8.3.1 .
14. The seismic fortification frame, the length and thin ratio of the central support and the width and thickness ratio of the plate do not comply with the specifications.The main function of the central support of the frame is to reduce interlayer displacement and ensure overall stability of the structure. Under the action of earthquakes, the restorative force characteristics of the frame support system mainly depend on the compression behavior of the support rod. The length and thinness of the support are larger than that of the support, the hysteresis circle is smaller and the ability to absorb energy is weak. The length and thin ratio of the support rod should be designed according to the earthquake resistance level according to the earthquake resistance specifications.
limits the width-thickness ratio of the central support plate to prevent local instability of the plate. The central support inclined rod should adopt a biaxial symmetric cross-section. If a uniaxial symmetric cross-section is used, effective structural measures should be taken to prevent buckling about the axis of symmetry. As shown in the figure below, add re-dividing rods and other measures to support the herringbone oblique rod.
"Construction Seismic Design Code" GB50011-2010 Article 8.4.1 .
15. The width-thickness ratio of the flange plates of the eccentric support energy-saving beam section and the non-energy-saving beam section of the same span exceeds the limit specified in the specification.
limit value energy dissipation beam section width-thickness ratio is mainly to ensure that the energy dissipation beam section has good ductility and energy consumption capacity, so it is stricter than ordinary beams. In addition, the steel of the energy-saving beam section should be Q235, Q345, Q345GJ. When the upper flange of the beam is fixed to the floor slab but does not indicate that its lower flange is fixed sideways, lateral support is still required.
"Construction Seismic Design Code" GB50011-2010 Article 8.5.1 .
16. When the beam and the column are rigidly connected, the column is within 500mm of each upper and lower edges of the beam. The connection weld between the column flange and the web or box column wall panels does not use fully melted bevel welds according to the specifications.
Under the action of a rare earthquake, the frame nodes will enter the plastic zone. In order to ensure the integrity of the structure in the plastic zone, the column is placed within 500mm each upper and lower edges of the beam. The connection weld between the column flange and the web or box column wall plate adopts a fully melted bevel weld.
"Construction Seismic Design Code" GB50011-2010 Article 8.3.6 .
17. The column foot of the high-rise steel structure frame column does not use rigid column foot.
exposed column foot is generally a hinged column foot, usually used for axial compression column. For the connection between high-rise steel structure frame columns and foundations, rigid column feet are generally used. Rigid column feet are divided into embedded column feet and outsourcing column feet. Rigid column feet generally have M, N, and V forces. The Hanshin earthquake in Japan showed that exposed column feet were seriously damaged, and buried column feet should be used in high-rise steel structures.
"Technical Regulations for Steel Structures for High-rise Civil Buildings" JGJ99-98 Article 8.6.2 .
18. The fire resistance limit of the floor slab was determined to be 1.5h. No protective measures were taken in the pressed steel plate. The concrete above the top of the ribs of the pressed steel plate is still 50mm, but does not meet the fire protection requirements specified in the regulations. The fire resistance design of the structure should first determine the fire resistance level of the building, and then determine the fire resistance limit based on the fire resistance level, and then take protective measures. When pressed steel plates are used as load-bearing structures, fire protection design should be paid attention to.
"Technical Regulations for Steel Structures for High-rise Civil Buildings" JGJ99-98 Article 7.4.6 .
6, other
1, the design service life of the structure is not indicated.
Design service life is the period when the structure or structural components specified in the design can be used for their intended purpose without overhaul. It is clarified that the design service life is a period specified in the design. During this specified period, only normal maintenance is required without overhauling, and the predetermined function can be used as expected, namely the service life that the house should achieve under normal design, normal construction, normal use and maintenance. The so-called "normal maintenance" includes necessary inspection, protection and repair. The design service life is the concretization of the "reasonable service life" of the foundation engineering and the main structure engineering of the house building. The design benchmark period is the time parameter selected to determine the values of variable effects and time-related material properties, and it is not equivalent to the design service life of the building structure. The load statistical parameters are generally determined based on the design base period of 50 years. The actual life of a house is also different from the design service life. The house can continue to be used after being identified and reinforced after being approved.
"Unified Standard for Building Structure Reliability Design" GB50068-2001 Article 1.0.5 .
2. The security level of the structure is not indicated.
is divided into three safety levels according to the severity of the consequences of the damage of the building structure. Among them, a large number of general buildings are included in the intermediate levels, and important buildings are raised one level; secondary buildings are lowered one level. As for the division of important buildings and secondary buildings, it should be determined based on the consequences of the damage of the building structure, that is, the severity of endangering human lives, causing economic losses, and causing social impacts.
"Unified Standard for Building Structure Reliability Design" GB50068-2001 Article 1.0.8 .
3. The project design is carried out based on the survey results documents (such as foundation processing plan, foundation selection, ground endurance, etc.).
has insufficient understanding of the authoritative nature of the survey report. When there is any doubt, you should communicate with the survey unit. After the two parties reach an agreement, the survey unit should issue a supplementary survey report as the basis for design.
Article 40 of the "Regulations on Survey and Design Management of Construction Engineering" If one of the following acts violates the provisions of this Regulation and commits any of the following acts, it shall be punished in accordance with Article 63 of the "Regulations on Quality Management of Construction Engineering":
(1) The survey unit conducts survey according to the mandatory standards for engineering construction;
(2) The design unit conducts engineering design based on the survey results documents;
(3) The design unit specifies the manufacturer and supplier of building materials and building components;
(4) The design unit fails to design according to the mandatory standards for engineering construction.
1. The value of the protective layer of the steel bar is incorrect (mainly the protective layer of the waterproof concrete in the basement, the protective layer of the steel bar when the low-grade concrete is used, and the steel bar protective layer of the column).
2. The cracks in the basement waterproof concrete do not meet the requirements of 0.2mm.
3. Frame-support shear wall structure, the seismic resistance level of the shear wall is not distinguished from the bottom reinforcement area (the key is the height of the frame-support layer plus the height of the two layers above the frame-support layer) and the non-reinforcement area.
4. The height and thickness ratio of masonry does not meet the specification requirements.
5. The layout of the structural column does not meet the requirements of the specifications (mainly on both sides of the large hole).
6. Calculation of basement exterior wall strength, load sub-coefficient did not take into account.
