Robustness Analysis Of Prestressed Assembled Frame Structure Based On Bearing Capacity

With the rapid development of my country’s economy and the advancement of science and technology,construction industrialization has once again become a hot spot in the development of the engineering sector under the vigorous promotion of national policies.The pre-loaded assembly structure has a fast construction progress,saves resources and protects the environment,and also has good seismic performance.In the past,the study of the continuous collapse performance of the structure was mainly based on the consideration of the external force action based on the horizontal seismic direction and the content based on the source of resistance,and few studies on the robustness of the structure against the vertical continuous collapse ability.(1)First,based on the static load test research of the plane three-layer pre-compressed assembled frame structure,considering the semi-rigid characteristics of the pre-compressed assembled node and the cast-in-place node,the test process is completed in the SAP2000 finite element software The numerical simulation,the calculated base shear displacement curve and the development mode of plastic hinge are in good agreement with the test results.(2)Secondly,design a five-story space preloaded assembled frame structure and corresponding cast-in-place structure.Four different failure conditions were analyzed for the demolition of the bottom layer:corner column,short-side center column,long-side center column and internal column.The development rules of plastic hinges under different working conditions of prestressed assembled frame structure and cast-in-place structure were obtained,and the robustness of both was quantified by calculating the vulnerability coefficient of structural members and the importance coefficient of structural members.(3)Finally,the parameters including vertical load,cross-sectional area of prestressed steel bar,concrete strength level,longitudinal steel bar strength and other parameters were changed by the control variable method,and the uncertain factors affecting the robustness of the prestressed prefabricated frame structure were analyzed.The results show that:(1)The modeling method considering the semi-rigidity of the nodes can better reflect the characteristics of the pre-assembled frame structure,and the numerical simulation results are closer to the test values and more accurate.(2)Compared with the cast-in-place structure,the prestressed pre-stressed steel bar improves the ductility of the member,but due to the pre-compression in the pre-assembled frame structure and the special splice beam-column node structure,it is not conducive to the structure The robust performance of vertical continuous collapse;compared with the cast-in-place structure,the ultimate bearing capacity of the intact structure of the pre-assembled frame structure is reduced by 13.8%.Compared with the cast-in-place structure,the ultimate load-bearing capacity of the corner column,long-side center column,short-side center column,and center column is lowered sequentially:9.7%,15.3%,7.3%,29.1%.(3)The seven uncertain parameters studied in this paper have an impact on the robustness of the structure in order:vertical load,the number of layers where the component is removed,the concrete strength grade of the column,the longitudinal reinforcement strength grade,the section area of the prestressed steel bar,and the strength of the prestressed steel bar Grade,the concrete strength grade of the beam.