Research On Seismic Shaking Table Hybrid Test Method For Substructure Of Steel Frame

Due to the limitation of table size and bearing capacity,it is difficult to carry out large scale model test on large and complex structures.The substructure technology is applied to the shaking table test to form the substructure seismic simulation shaking table hybrid test method.By combining numerical analysis and physical loading,the part that is prone to nonlinear under the earthquake is taken as the test substructure and arranged on the shaking table for physical test.The rest of the structure is simulated by computer as a numerical substructure,and the dynamic analysis of the whole structure is realized by integrating the two parts.This method can expand and improve the test capability of shaking table test.In this hybrid test method,boundary condition simulation of test substructure and real-time loading control of actuator are still the difficulties in the test.Theoretical and experimental studies are carried out in this paper for the above problems.The main research and work contents are as follows:(1)In this paper,the application of hybrid test platform and system development is described,the boundary condition simulation method of hybrid test is summarized,and the research status of substructure seismic simulation shaking table hybrid test at home and abroad is introduced in detail.(2)Analysis of hybrid substructure shaking table test method and test process,the basic principle of boundary conditions are simulated based on hybrid test,load control and research of numerical integration algorithm,based on the inflection point method and the overlapping domain method combining simulation test substructure boundary conditions,the extension of the load boundary to frame structure inflection point location,and at the same time considering interaction between substructure,Finally,the boundary degree of freedom of the test substructure is simplified to facilitate the test loading.(3)In order to verify the feasibility of the substructure boundary condition simulation method,a incomplete scale three-story steel frame structure was designed and the shaking table test was carried out.The experimental results analyze the seismic performance of the frame structure from the aspects of acceleration,displacement and strain response,and provide the basis for data comparison.The comparison between the displacement response results and the numerical simulation results is basically consistent with a high degree of agreement.(4)In order to verify the correctness of the substructure hybrid test method,two trusses of one and a half three spans of the three-story steel frame structure were selected as the substructure to conduct the hybrid test.Firstly,the bottom layer of the structure was selected as the test unit,and the loading boundary was extended to the position of the second floor column based on the inverse bending point method.Then in the hybrid test system,the numerical integration algorithm and sending commands are programmed by C++ language.Finally,the coordinated loading of the test substructure was carried out by the actuator and shaking table,and the real-time loading control was successfully completed and the dynamic response of the structure was obtained.The results of the substructure hybrid test are in good agreement with the results of the whole structure shaking table test from the perspective of displacement response and strain response,and their development and variation tend to be consistent,which verifies the correctness of the hybrid test method and the simulation of the boundary conditions of the substructure.