Study On The Seismic Behavior Of Lower Frame Structure Influenced By Simplified Space Truss Model

At present,the application range of grid structures developing from large to small and medium-scale public buildings,such as auditoriums,libraries in primary and secondary schools,and concrete frame structure,frame shear wall structure is used to support the grid structure usually.Designing the architecture of different materials separately will lead to stucture unsafe.However,the current methord of grid simplified model does not consider its horizontal equivalent stiffness.Adopting integral method for supporting structure design,the effect on supporting structure of different simplified model of grid may be different under the earthquake.Therefore,using the integral method to design the structure which upper is steel truss while the lowe r is concrete frame,it is a urgent problem for engineering project to improve the efficiency that explore the influence of simplified grid model on the seismic performance of the lower concrete supporting structure.In this paper,the influence of the sp ace truss structure on the damping ratio of the whole structure is discussed;the different simplified structure of the space truss structure is established,and the modal analysis,response spectrum analysis and time history analysis of whole structures a re carried out,the effects of different simplified models on the seismic performance of the lower supporting frame structure are compared;a practical project is taken as an example to applied the results of this study.The results show that the stiffness of the lower concrete frame structure is larger than the space truss,and the upper grid structure has little influence on the damping ratio of the lower frame structure;the methord simplifing the grid structure that only considering the load on the space truss and ignoring its stiffness will make great difference from truth when analyse the seismic performance of the concrete frame structure;by using the equivalent stiffness plate method,fully rigid plate method simplifies the structure will lead to the lower frame' period is larger,the internal force is smaller,and the displacement of columns is smaller,the span of the space truss is smaller,the error of the simplified model is smaller,when the span of the structure is less than 30 m,the equivalent stiffness plate method and the rigid plate method can be used to simplify the grid structure;O nly in a certain floor,the simplified model of the grid structure will affect the lateral stiffness of the multistory frame structure.