Influence Of Different Truss Forms On Seismic Performance Of Multi-story SSTF Structure

Steel structure has the advantages of light weight,high strength,good plasticity and toughness,strong prefabrication,and convenient construction.It is widely used in civil construction,industrial building structures,large-span grid structures,high-rise structures and other building structures,especially in areas with high seismic fortification intensity requirements,and have gradually developed into one of the mainstream architectural structures.The steel staggered truss framing(SSTF)structural system is a new type of structural system developed on the basis of the steel frame structural system.It is an efficient,practical and economical structural system,which is superior to ordinary steel frame in both architectural functions and mechanical properties.The research and popularization of this structural system conforms to the development direction of building structures in China.The purpose of this paper is to study the influence of different truss arrangement forms on the seismic performance of the multi-layer SSTF structural system model,as well as the seismic performance and seismic demand performance of the SSTF structural system in the medium and high seismic fortification areas.The built structure model selects the seismic fortification intensity of 9 degrees,and the 5-story ordinary steel frame structure and the 5-story SSTF structure are taken as the research objects,seven research models are established with different truss layout forms,whether P-Δ effect is considered or not,and two different connection methods of rigid connection and hinged connection between the vertical web member and the chord in truss as the research variables.The static and dynamic analysis were performed with CLAP software.Through the elasto-plastic static pushover analysis based on displacement control of the structural model,the seismic performance of each structure is studied,such as the order and distribution of plastic hinge,the relationship between shearing force and displacement between floors,the variation of stiffness and bearing capacity of the first floor,and the influence of P-Δ effect.Then the damage analysis of each structure is carried out.After that,input 5 natural seismic waves and 2 artificial waves in compliance with my country’s "Code for Seismic Design of Buildings" for each model,and perform elasto-plastic dynamic time history analysis on each structural model based on the principle of energy balance,to study the maximum story shear force,the maximum story deformation,residual deformation and elasto-plastic energy of each member of each story is analyzed,and the dynamic response law of different structural models is obtained by analyzing the energy consumption process of the structure.The research results show that the SSTF structure has a better seismic effect than the pure frame model.The additional members in truss(vertical web members and BRB)significantly increases the shear force and stiffness of the first story,and significantly improves the lateral resistance of the structure.In addition,the large amount of yield in the early stage absorbed more seismic energy,delayed the forming time of plastic hinges of structural columns and beams,played a good effect of energy dissipation and shock absorption,and gave full play to the role of the first line of defense against earthquake.In addition,the greater the number of additional members in the truss and the rigid connection at both ends of the vertical web members,the stronger the lateral resistance of the model,the more obvious the shock absorption effect of the structure,the smaller the overall residual deformation of the structure,and the seismic performance better.