| High ductile concrete(HDC)has the characteristics of high ductility and multi-crack development.It can make full use of the good mechanical properties of HDC to repair and strengthen the earthquake-damaged structure.Based on this,this thesis uses HDC to reinforce 10 seismic damaged frame truss composite walls,and studies the seismic performance of HDC strengthened composite walls through quasi-static test,which provides certain reference and basis for the repair and reinforcement of engineering seismic damaged structures.The main research contents and results are as follows:(1)HDC was used to reinforce the composite wall with seismic damaged frame truss according to the method of increasing section,and the thickness of reinforcement layer was 20 mm.According to the loading system of the original test piece,the pseudo-static test was carried out on the strengthened composite wall to study the influence of different axial compression ratio and whether there is steel plate inside the wall truss rod on the seismic performance of the strengthened composite wall.(2)The test results show that the axial compression ratio and whether there is steel plate in the embedded truss have greater influence on the seismic performance of the composite walls strengthened by HDC.Increasing the axial compression ratio properly can improve the bearing capacity of the test piece,but it will reduce the ductility of the test piece and accelerate the rigidity degradation of the test piece.When the steel plate is not built into the truss,the peak bearing capacity can be increased by 12%～31.7%by increasing 0.1 axial compression ratio;when the steel plate is combined with HDC,the bearing capacity and ductility of the test piece can be improved,the rigidity degradation can be optimized,and the energy consumption capacity can also be effectively improved,in which the maximum peak bearing capacity can be increased by 24%,the maximum ductility coefficient can be increased by 16.5%,and the maximum energy consumption can be increased by 160%;When the axial compression ratio is 0.4～0.5,the seismic performance of the strengthened specimens is the best when the steel plate is built into the truss,the maximum axial compression ratio of the four truss specimens should not exceed 0.5,and the maximum axial compression ratio of the five truss specimen should not exceed 0.7.(3)Through the comparative analysis of the seismic performance of some HDC strengthened specimens and the original specimens,the feasibility of HDC strengthened earthquake damaged structures is verified.The results show that the peak bearing capacity of the specimens strengthened by HDC can be increased by 24%～43.5%.The ductility of the specimen is also better restored and improved,the ultimate displacement is increased by 5%～43%,the total energy consumption is 90%higher than that of the original specimen,and the maximum energy consumption can be increased by 330%.The energy consumption capacity of the specimen is significantly better than that of the original specimen,and the seismic performance of the specimen has been effectively restored and improved.The results show that HDC can be used to strengthen the earthquake damaged structure.(4)Based on the test data,on the basis of the quasi-static test,the skeleton curves of 10 HDC strengthened frame truss composite walls are simulated and compared with the test curves.In this thesis,the restoring force model of frame truss composite wall strengthened by HDC is proposed,and the hysteretic rule of the model is analyzed by loading and unloading stiffness.The comparison between the fitted skeleton curve and the measured curve shows that the results of the restoring force model are consistent with the test curve,which indicates that the restoring force model can be used to study the hysteretic characteristics of the frame truss composite wall strengthened by HDC under low cycle repeated load. |
PDF Full Text Request