| Due to the change in the use function,adding or expanding a hole in the shear wall will change the seismic performance of the shear wall such as bearing capacity,stiffness,deformation capacity,and energy consumption capacity.If the opening is not reinforced in a targeted manner,when the earthquake strikes,local damage may occur,causing huge losses.Therefore,the paper investigated the influence of post-construction opening on the seismic performance of shear walls.Through the pseudo-static test,the influence of the post-construction opening on the seismic performance of the shear wall was obtained.According to the weakening of the shear wall by the post-construction opening,the flat steel and CFRP were used to strengthen the shear wall of postconstruction opening to analyze the reinforcement effect of the steel and CFRP.Finally,the model of the restoring force of the shear wall of post-construction opening,the bearing capacity reduction factor of the post-construction opening shear wall and the stiffness reduction factor of the post-construction opening shear wall were investigated.The main research results of this article were as follows:(1)A pseudo-static test was performed on the pre-opening shear wall with steel reinforcement and the non-opening shear wall.The influence of the pre-opening on the seismic performance of the shear wall was compared and analyzed.The research results showed that the stiffness of the pre-opening shear wall with reinforced reinforcement was slightly smaller than that of the non-opening shear wall,and its peak bearing capacity was close to the peak bearing capacity of the non-opening shear wall,but the energy consumption capacity was reduced by 17%,and ductility was reduced by 23%.(2)A pseudo-static test was performed on the post-opening shear wall lacking steel reinforcement for the opening.The post-construction opening shear wall's seismic performance were compared and analyzed with the pre-opening shear wall and the nonopening shear.The results showed that the lack of reinforcing steel at the opening caused severe shear deformation in the opening area,and the peak bearing capacity was reduced by approximately 16.5% compared with the opening of the pre-opening.When the peak bearing capacity was reached,brittle failure occurred without obvious signs of damage such as bearing capacity decreasing and steel bars broken.The ductility of the post-opening shear wall was similar to that of the pre-opening shear wall with reinforced steel,but the energy consumption capacity was reduced by 5.8%.(3)Aiming at decreasing the severe shear damaged at the post-construction opening,and reducing the impact on bearing capacity,stiffness,and energy dissipation capacity,two methods of strengthening with flat steel and CFRP were adopted.Pseudostatic tests were conducted and it was found that flat steel and CFRP reinforcement can effectively restrain the cracks at the corners of the opening,reducing the shear failure of the opening,and significantly increase the energy dissipation capacity.The ductility of the post-opening shear wall was slightly improved by the steel reinforcement,but the ductility of the post-opening shear wall strengthening with CFRP was not enhanced.(4)Based on the experimental data,the mathematical model of the skeleton curve of the tri-fold line without descent was derived through regression fitting.The hysteresis rule of the post-opening shear wall was determined by referring to the test hysteresis curve and the post-opening restoring force model was obtained.Based on the calculation model of the bearing capacity and stiffness reduction coefficient of the preopening shear wall proposed by the Architectural Institute of Japan and Masayuki Ono,the calculation formula for the bearing capacity and stiffness reduction coefficient of the post-opening shear wall was determined and verified.It can be the reference of seismic reinforcement scheme of the shear wall.The paper consists of 71 figures,24 tables and 96 references. |
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