Experimental Research On Seismic Performance Of Horizontal Buckle-bar Connection Of I-shaped Fully Prefabricated Superimposed Shear Wall

In order to improve the horizontal splicing assembly efficiency of prefabricated laminated shear walls,This paper explores the efficient and reliable method of horizontal reinforcement connection and template-free technology,improves the original method of horizontal rebar ring-bar connection,and puts forward a new method of horizontal reinforcement connection-buckle-bar connection.Attempts are made to prefabricate the restrained edge members and walls as a whole.Design specimens to carry out mechanical and seismic performance tests,verify the connection performance of the new horizontal buckle-bar connection method,carry out analysis of the seismic performance of horizontal connection belt and shear wall as a whole,obtain the seismic performance design calculation method of the fully prefabricated composite slab concrete shear wall.The construction requirements and suggestions of the buckle-bar connection and formwork-free prefabricated members are given.In order to explore the connection performance of the buckle-bar and the structural requirements,including angle on bending and length of the straight bar after bending,the ensile tests were carried out on 9 specimens of horizontal buckle connection.The test results show that the buckle bar connection can transmit force effectively under tension;the longer the length of the buckle bar bending straight section,the stronger the deformation capacity of the connection;the bending of 180-degree angel and 90-degree angel about buckle-bar can ensure the mechanical performance of the connection when the anchorage length of the straight bar after bending is sufficien.In order to make the rebar ring-bar connection more suitable for laminated plate shear wall and realize the integral prefabrication of the restrained edge members and the wall,the rebar ring-bar connection is optimized.Tensile tests of 7 specimens and axial compression tests of 6 specimens were carried out.The test results show that the width of the connecting steel ring should not be too small when the connected steel ring in prefabricated composite slab shear wall is not bended and changed its way.If it is too small,it is easy to cause large tensile deformation of the connecting steel ring,what's more,the effect of connection is not good.When the minimum volume stirrup ratio specified in the code is satisfied,horizontal connection steel ring with large diameter can replace original stirrup ring and horizontal connection steel ring.Both of them can form a good restraint effect on the concrete in the confined edge zone of members.In order to further investigate the connection performance of buckle bars and the overall seismic performance of fully prefabricated composite plate shear walls,carry out the Seismic performance tests of two I-shaped precast superimposed slab shear walls and one cast-in-situ common shear wall,the failure modes,load-displacement curves,stiffness,ductility,energy dissipation capacity and strain change process of the specimens were obtained.The comparative study knows that: the ductility of prefabricated wall is better and the yield displacement is larger than that of cast-in-place wall;the ductility and energy dissipation capacity of the prefabricated members can be increased by splitting and assembling the wing swab wall,but there is little effect on the peak bearing capacity of the members by that way;Whole shear failure of shear wall occurs;The strain change trend of the connecting bar and connected bar is the same,which indicates that the connection of the buckle-bar is reliable.Based on the results of seismic test and relevant documents and codes,the shear behavior of the horizontal connection strip and whole sections of precast formwork-free superimposed slab shear walls is analyzed from the aspects of failure mode and steel strain.The shear performance of the horizontal connection strip of fully prefabricated composite plate shear wall is good and the overall shear performance is guaranteed.The formulas for calculating the shear capacity and the detailed structural requirements of the buckle connection are put forward.