1, the role of steel bars in shear walls There are more kinds of steel bars in shear walls than in cast-in-place reinforced concrete frame structures, and different kinds of steel bars play completely different roles in shear walls. Therefore, in order to carry out the construction of steel bars in shear wall structure, it is necessary to fully understand the types of different steel bars in shear wall structure, so as to help builders fully understand the stress and deformation of different steel bars and rationally arrange all kinds of steel bars. 1. 1 shear wall structure, the shear force borne by the shear wall is mainly borne by the horizontally distributed steel bars in the shear wall, which can effectively prevent oblique cracks in the shear wall structure; In addition, as long as the horizontal steel bars are reasonably arranged in the calculation and layout, the brittle failure of the shear wall structure can be effectively avoided. Therefore, the reasonable arrangement of horizontal steel bars plays a key role in the shear performance of shear walls. 1.2 vertically distributed reinforcement In the shear wall structure, the bending moment of the shear wall is mainly borne by the vertically distributed reinforcement in the shear wall, and the vertical reinforcement can also effectively prevent horizontal cracks in the shear wall. Therefore, the accurate arrangement of the diameter and spacing of vertical steel bars plays a major role in the flexural performance of shear walls and the prevention of oblique cracks. 1.3 There must be a concealed column structure in the reinforced shear wall structure with concealed columns, which plays an important role in the shear wall structure. Most of the flexural reinforcement of shear wall is arranged at the end of shear wall, that is, the reinforcement of concealed column. The reinforcement of concealed column can not only restrain the concrete of shear wall, but also ensure the stability of shear wall and improve the ductility of shear wall. For concealed column reinforcement, stirrups must be set in addition to the vertical direction. 2. Layout of steel bars in shear wall From the above analysis, it can be found that steel bars in different positions in shear wall structure play different roles, for example, the layout direction of vertical horizontal steel bars and horizontal distribution steel bars are completely different, and the mutual positions of the two kinds of steel bars are also completely different. How to judge the types of steel bars according to the construction drawing and rationally allocate steel bars is the key to the steel bar construction of shear wall structure. (1) Horizontal reinforcement arrangement. The horizontal distribution of steel bars in shear wall structures is usually double-row horizontal arrangement. When arranging horizontally distributed steel bars, vertically distributed steel bars should be arranged on the inside and horizontally distributed steel bars should be arranged on the outside. This reinforcement arrangement is mainly used to resist temperature stress and prevent concrete from cracking due to temperature. For slender walls, this reinforcement method should be adopted. (2) Vertical distribution of reinforcement. In general, vertically distributed steel bars are arranged on the inner side of horizontally distributed steel bars, and vertically distributed steel bars are suitable for continuous and uninterrupted concealed beam crossing. When passing through the concealed beam, the vertically distributed steel bars are also suitable to be arranged in the longitudinal steel bars of the concealed beam. Moreover, shear walls are usually double-layered steel bars distributed vertically. If the thickness of the shear wall is small, the vertically distributed reinforcement can also be arranged outside the longitudinal reinforcement of the concealed beam. However, no matter whether the vertically distributed reinforcement is arranged outside or inside the longitudinal reinforcement of the concealed beam, it is necessary to fix the vertically distributed reinforcement with the longitudinal reinforcement of the concealed beam with Rachel reinforcement to increase the restraint effect on the vertically distributed reinforcement. (3) Reinforcement of coupling beam and concealed beam. The longitudinal reinforcement of coupling beam in shear wall at both ends should be arranged at the innermost side of all members, that is, the longitudinal reinforcement of coupling beam should be arranged at the inner side of horizontally distributed reinforcement and vertically distributed reinforcement. The longitudinal reinforcement of the concealed beam should be arranged in the longitudinal reinforcement of the concealed column at both ends, and both ends should be anchored in the concealed column. 3. Anchorage of reinforcement in shear wall In the reinforcement project of shear wall structure, the bearing capacity of members is mainly reflected by calculating the amount of reinforcement and rationally arranging reinforcement, while the seismic structural measures of the structure are reflected in the anchorage of reinforcement. For the reinforcement engineering construction, the anchorage of reinforcement is a key technical point. (1) Minimum anchorage length of reinforcement. The steel bar anchorage in shear wall structure must meet the minimum anchorage length specified in the code to ensure the construction measures. According to the Technical Specification for Concrete Structures of High-rise Buildings, when the seismic grade is Grade I or II, the minimum seismic anchorage length LaE of steel bars in the shear wall structure in the seismic area is:1.15la; Take1.05la; When the seismic grade is Grade III; Take 1.0La when the seismic grade is level 4. (2) Anchorage of horizontally distributed steel bars. The horizontally distributed reinforcement of shear wall shall extend to the wall end, and be cut off after being bent horizontally inward 10d, where d is the diameter of horizontally distributed reinforcement. When there is a wing wall or corner wall at the end of the shear wall, the horizontal distribution steel bars on both sides of the inner wall and the horizontal distribution steel bars on the inner side of the outer wall should extend to the outer side of the wing wall or corner wall, and then be cut off after being bent horizontally on both sides, and the horizontal bending length should not be less than 15d. At the corner wall, the horizontally distributed reinforcement outside the external wall should be bent into a wing wall at the outer corner of the wall end and overlapped with the horizontally distributed reinforcement outside the wing wall. The splicing length is1.21a. For shear walls with frames, the horizontal and vertical distribution of steel bars should pass through columns and beams respectively or be anchored in columns and beams. (3) Anchorage of vertically distributed steel bars. The vertical distribution of steel bars in shear walls is usually anchored on the foundation wall or basement. When the upper and lower walls are equal in thickness, the vertical distribution of steel bars in shear wall structure should be staggered and overlapped; When the thickness of the upper and lower walls is not equal, the vertically distributed steel bars of the shear wall structure directly extend into the foundation or basement wallboard for anchorage, and the minimum anchorage length is taken as the minimum lap length. 4. Connection of reinforcement in shear wall In the reinforcement engineering of shear wall structure, the reinforcement connection methods mainly include binding connection, mechanical connection and welding connection, especially binding connection. Therefore, this paper focuses on the binding connection points of steel bars in shear walls. (1) Vertical distribution of reinforcement. The length of each section of longitudinal reinforcement of shear wall shall not exceed 4m (reinforcement diameter is 12mm), and the length of each section of horizontal reinforcement shall not exceed 8m for binding. The vertically distributed steel bars in the shear wall can be overlapped at the same height, and the overlapping length should not be less than 1.2la. (2) the horizontally distributed steel bars. The length of horizontally distributed reinforcement in shear wall should not be less than 1.2 la(la is the anchorage length of reinforcement). The net spacing along the horizontal direction between the horizontally distributed steel bar joints in the same row and between the upper and lower adjacent horizontally distributed steel bar lap joints should not be less than 500mm. (3) Other points of steel binding. Straighten and straighten the reserved reinforcement, and clean up the surface mortar and other sundries. First, set 2 ~ 4 longitudinal bars, and make grading marks for the transverse bars, then tie two positioning transverse bars at the lower part and chest level, and make grading marks on the transverse bars, then tie the remaining longitudinal bars, and finally tie the remaining transverse bars. When there are concealed beams and columns in the shear wall, the concealed beams and columns should be tied first, and then the surrounding transverse steel bars should be tied. Steel mesh binding of shear wall. All intersections of steel bars shall be fastened, and the wires of adjacent binding points shall be buckled into a figure of eight when binding, so as to prevent the mesh from being skewed and deformed. Before concrete pouring, the protruding wall reinforcement should be trimmed, and temporary transverse reinforcement should be tied to fix the spacing of protruding reinforcement (the spacing of dumped reinforcement). When pouring concrete on the wall, assign special personnel to look after the reinforcement, and immediately repair the protruding reinforcement after pouring (the reinforcement is rejected). 5. Conclusion The reinforcement construction of frame shear wall is a construction difficulty that attracts much attention. However, some builders have not fully understood the correct construction of steel bars in frame shear walls. This paper introduces the construction technology and method of steel bars in frame shear wall structure in detail, and from the role of steel bars in shear wall, analyzes the position relationship, anchorage and connection technology of steel bars in shear wall.
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