| Shear wall structures are widely used in high-rise buildings because of their good integrity,clear force transmission and superior seismic performance.However,due to insufficient material strength,non-standard construction and some buildings have reached the designed service life and other reasons,many shear wall structures can not continue to resist natural disasters such as earthquakes,nor can they meet people’s requirements for the use of function.Therefore,it is of practical significance to strengthen shear wall structures and study their seismic performance.In this thesis,the local displacement method is used to strengthen the concrete shear wall,and the modified active powder concrete(MRPC)is used as the replacement material by taking advantage of its excellent durability and toughness.In order to study the seismic performance of local displacement of concrete shear wall,a total of 5 shear wall specimens were designed and produced,including 1 specimen that did not reach the designed strength,1 specimen that met the original design strength,1 specimen that used MRPC to replace the middle part of the wall and 2specimens that used C45 concrete to replace the wall and MRPC to replace the wall.Pseudostatic tests were carried out on five shear wall specimens,and the seismic performance indexes such as bearing capacity,stiffness degradation,displacement ductility and energy dissipation capacity of each wall specimen were analyzed,and some strain data of reinforcement and concrete were selected for force analysis.Finally,the theoretical calculation and finite element simulation analysis of the shear capacity of 5 shear wall specimens were carried out.According to the test and simulation analysis results,the following conclusions are drawn:(1)By adjusting the steel fiber content and the amount of water reducing agent,the MRPC with moderate strength and good fluidity was prepared.The MRPC prepared under the mix ratio has good adhesion with the wall.(2)Under low-cycle cyclic load tests,the seismic performance indexes of the other four specimens,such as bearing capacity,displacement ductility,stiffness degradation and energy dissipation capacity,were significantly improved compared with those of substandard specimen SW1.Compared with SW2,SW4 and SW5 at both ends of the shear wall replaced by C45 concrete and MRPC effectively improve the bearing capacity,energy dissipation capacity,ductility and other seismic properties of the shear wall.The seismic performance of SW3 in the middle part of the wall replaced by MRPC is slightly worse than that of SW2.(3)The replacement material of SW3 and SW5 is MRPC.Compared with SW3,the peak bearing capacity,ductility coefficient,ultimate displacement Angle and cumulative energy dissipation of SW5 are increased by about 13.9%,10.5%,39.5% and 62.8% respectively.SW4 and SW5 are replaced by two ends.Compared with SW4,SW5’s peak bearing capacity,ductility coefficient,ultimate displacement Angle and cumulative energy dissipation increase by about6.9%,about-0.3%,and 7.9% respectively.The results show that MRPC and shear wall specimens have good collaborative performance.Meanwhile,the displacement of both ends of the shear wall by MRPC can effectively inhibit the development and extension of cracks,slow down the stiffness degradation process of the specimen,and significantly improve the seismic performance of the shear wall.(4)Through the analysis of reinforcement strain data and concrete strain data,it is found that the shear wall specimen has a good force transfer mechanism,and the wall has a clear force.Meanwhile,by comparing and analyzing the strain data,it is concluded that the change of strain value can better reveal the failure mechanism of the specimen and correspond to the final failure phenomenon of the specimen.(5)The theoretical analysis of the partial displacement specimen of shear wall is carried out,and the corresponding calculation formula of shear capacity is obtained.The difference between the calculation result and the test value is small,which provides a theoretical basis for the practical engineering application in the later stage.(6)Based on the finite element analysis software ABAQUS,numerical simulation analysis was carried out on the above 5 shear walls.According to the DAMAGEC distribution cloud map and skeleton curve,it can be seen that: Compressive damage(DAMAGEC)distribution cloud map can well reflect the compressive damage condition of concrete material,and the simulated skeleton curve is basically consistent with the test skeleton curve,which proves that the numerical simulation analysis can well reflect the seismic performance of the local displacement of concrete shear wall. |
