Study On The Anti-seismic Performance Of Steel Staggered Truss Structure With Infilled Walls

The member size of steel staggered truss structure system is smaller comparatively, the structure anti-seismic performance is influenced by infilled walls apparently, papers about the influence have not been published until now. In this paper, the theoretical investigation and numerical analysis of the influence are carried out for the anti-seismic performance of steel staggered truss structure with infilled walls. The model is built to do the analysis by the equivalent synclinal compressive pole instead of the infilled walls, the period reduction factors are recommended. Study on the yield mechanism and the anti-seismic performance of steel staggered truss structures with infilled walls, the weak components and weak storeys are pointed out. The method is recommended to improve the yield mechanism of the longitudinal structure, some design advices about the anti-seismic construction measurement of infilled walls and RC slabs are suggested. What has been studied is to provide technical references for the design specifications of steel staggered truss structure system that is being compiled and updated in china.The main contents in this paper are as follows:(1) Based on the experiment of steel frame structure with infilled walls, the process of numerical simulation analysis is tested and verified. The simplified analysis model of equivalent synclinal compressive pole instead of the infilled walls is built according to the stress arrangment regulation in the infilled walls and referring to the research works of infilled walls. The numerical simulation analysis is carried out for steel staggered truss structures with infilled walls considering the material nonlinearity、 geometric nonlinearity and contact nonlinearity simulating the relationships of steel bar links and face to face contact for the infilled walls with the main steel structure. It is verified to be workable to do the structure nonlinear analysis adopting the equivalent synclinal compressive pole model.(2) The range of the period reduction factors is suggested for the steel staggered truss structures with infilled walls considering the stiffness of infilled walls. Study on the influence of the infilled walls for the steel staggered truss structure about natural period and modal of vibration based on many analysis models. The simplified analysis model of equivalent synclinal compressive pole is verified to be accurate for structure natural period analysis.(3) The anti-seismic performance of steel staggered truss structure is studied under the frequent earthquakes. The proposal is suggested to enhance the anti-seismic design for the first storey structure. Many models of steel staggered truss structures with infilled walls are built and the response spectrum analysis and dynamic time history analysis are carried out. The results of the storey drift、the displacement of top point and the base shear forces are studied comparatively with three conditions including of ignoring the infilled walls stiffness、using the finite element method for infilled walls and adopting the equivalent synclinal compressive pole model. The anti-seismic performance of steel staggered truss structures is evaluated considering the infilled walls.(4) Study on the seismic resistant capability and the yield mechanism of steel staggered truss structure system with infilled walls, the method is proposed to improve the yield mechanism of the longitudinal structure. The seismic resistant capability of structure for transverse direction and longitudinal direction are evaluated by working with the capacity graphs and the structure top point displacement relevant to the performance point comparing with the anti-seismic target displacement. Study on the structure relative stiffness design rationality、the structure overall safety and the structure overall plastic deformation capacity, based on the plastic-hinge sequence of appearance、the plastic-hinge capacity、the plastic-hinge distribution regularities and the yield mechanism of steel staggered truss structure with infilled walls, the structure weak components and weak storeys are pointed out. To improve the structure yield mechanism effectively, the method of adopting column bracing for the longitudinal structure and increasing the first storey steel columns stiffness and strength is suggested.(5) The suggestion of anti-seismic design connections between the infilled walls and the main structure coulmns is proposed for steel staggered truss structure with infilled walls, based on the contribution of infilled walls for structure anti-seismic performance, considering the general connections during the project design and construction process、the out of plane stability problem of infilled walls and the decoration maintenance problem during the process of service. Due to the infilled walls are the important components for the longitudinal links of steel staggered truss structure, the anti-seismic enhanced reinforcement is suggested to be adopted for RC slabs at some regions in the structure design process. The analysis of RC slab is done considering the influence of infilled walls under the effect of external forces.