1. Reinforcement bar binding and overlap
Reinforcement bar binding and connection should meet the corresponding requirements of the national standard GB50010 " Concrete Structure Design Specification ". In the construction site, tensioned steel bars generally refer to the longitudinal steel bars of beams, and compressed steel bars generally refer to the vertical steel bars of shear walls and columns.
is generally used as a steel bar for wall columns. Steel bars exceeding 22mm will not consider binding and connection, because the larger the steel bar, the higher the binding cost and the quality is difficult to guarantee. Most of them use welding, mechanical connection and other connection methods, one is to ensure quality, and the other is to be economical and reasonable.
. Advantages
1. Simple construction, fast speed, can adapt to various environments, and low construction costs.
2. No additional mechanical equipment is required for installation and inspection, and the quality is guaranteed.
2. Disadvantages
1. Rebar binding and connection requires overlap, and reinforcement is used more frequently.
2. The force transfer performance of steel bars is poor.
3. The binding and overlap of steel bars occupy the area of the components and may affect the pouring of concrete.
4. The steel bars are missing, and the construction conditions are not considered in advance, and the installation order of the steel bars is ignored, which makes it difficult to tie the steel bars in the next process.
5. The binding operation is not strict, and not binding according to the size of the drawing will lead to excessive spacing of the negative ribs.
(Picture of steel bar binding at construction site)
(Picture of steel bar binding at construction site)
(Picture of steel bar binding at construction site)
(Picture of steel bar binding at construction site)
(The main tendon under stress is not tied in place, which will cause hidden dangers)
2. steel bar welding connection
steel bar welding is connected with flash butt welding, arc welding , electroslag pressure welding , gas pressure welding and embedded parts steel bar submerged arc pressure welding . The five types of steel bars that are commonly used in construction are electroslag pressure welding, which are mostly used for columns and shear wall steel bar connections. The steel bar welding connection should meet the corresponding requirements of the national standard GB50010 "Concrete Structure Design Specifications" and the standard JGJ18 "Rebar Welding and Acceptance Regulations".
1. Advantages
1. This connection method does not affect the progress of other processes, which is conducive to improving construction efficiency.
2. Compared with binding, the requirements for steel bars are not strict and the conditions are more adaptable.
3. Since overlapping is not required, it saves steel and has obvious economic benefits.
2. Disadvantages
1. Special construction equipment, materials and electricity are required, and the power supply requirements are high.
2. Strict requirements for personnel and certain requirements for the construction environment. Construction cannot be carried out in rainy and snowy weather.
3. Inclined and horizontal steel bars exceeding a certain angle cannot be welded.
4. The quality controllability is poor, and the probability of unqualified products is high.
5. If the welding material is incorrectly matched with the base material, or the elements are burned during welding, etc., it is easy to cause the chemical composition of the weld metal to change, or the weld structure does not meet the requirements. This may lead to a decrease in the mechanical properties of the weld and will also affect the corrosion resistance of the joints.
6. If the welding specifications are used improperly, it will cause overburn and overheating, and the heat-affected zone will stay at high temperature for a long time, which will make the grains thicker, that is, overheated tissue will appear. If the temperature rises further and the residence time is longer, it may cause oxidation or local melting of grain boundary , resulting in overburning of tissue. Overheating can be eliminated by heat treatment, while overheating is an irreversible defect.
(Construction site steel bar welding pictures)
(Construction site steel bar welding pictures)
(Construction site steel bar welding pictures)
(Pneumatic welding quality defect)
3. Rebar mechanical connection
Rebar mechanical connection technology is a new type of steel bar connection technology, known as the "third generation of steel bar joints" after binding and electric welding. It has the advantages of joint strength higher than the steel base material, 5 times faster than electric welding, no pollution, and saving 20% of steel.At present, the new generation of steel bar mechanical connection technology on the market is the WL double screw sleeve steel bar mechanical connection technology developed by Beijing Wulongxing Technology Development Co., Ltd. The design and construction of double-screw steel bar connection joints should mainly be based on the provisions of 500MPa grade I joints in the industry standard " steel bar mechanical connection technical regulations " JGJ 107-2016.
1. Technical characteristics of mechanical connection of double screw sleeve steel bars
1. Solve the problem of non-collinearity of steel bars. By simply adjusting the relative position of the connector during the connection, the upper and lower thread trajectories of the butt steel bars can be adjusted to be collinear! Solve the problem of connecting parts steel bars in industrial construction.
2 and are easy to connect, simple and convenient to operate, fast construction speed, and only 20 seconds.
3, has high strength and good mechanical properties. It can bear the load after the connection is completed.
4, whether the quality of the steel bar connection is qualified can be visually tested, which is simple and clear.
5. On-site joint quality inspection is simple and fast, consistent with ordinary straight threaded joint .
6. No pollution meets environmental protection requirements, no electricity is used for construction, no open flame operation, and construction can be carried out all day without any obstacles in wind and rain.
This technology is developed by Beijing Wulongxing Technology Development Co., Ltd. and a new generation of steel bar mechanical connection technology. It can completely change the way traditional mechanical connections of steel bars require one connection at a time, and can become an overall connection between building parts (building components) and steel bar parts ( steel bar cage , steel bar mesh, etc.), which can greatly improve the construction speed of steel bars, and change the traditional large number of steel bars positioning, binding and other work that need to be completed on-site to the mechanized, automated and intelligent processing of steel bars, mechanical prefabricated and preformed at the construction site, and the overall installation and connection of steel bars at the construction site. It will completely change the construction status of steel bar engineering and is the core technology in the industrialization of steel bar engineering.
(connect internal screw sleeve 1 to lower steel cage)
(connect internal screw sleeve 2, external screw sleeve, lock mother to upper steel cage)
(put lower steel cage into hole pile)
(lift the upper steel cage to dock)
(align upper steel cage)
(align upper steel cage)
(connect wl double screw connector)
(connection completes quality inspection)
Conclusion Recommendation 1) Except for mechanical connections, all kinds of connectors have their own scope of application, and it should be noted that they cannot be used beyond the scope;
2) Although the price of mechanical connection connectors is relatively high, it is the most widely used due to the best quality and simple operation;
3) Although the price of welding connections is at the center, the market share is gradually decreasing due to high operating requirements, large energy consumption, and inability to be completely controlled.
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