Researches On Seismic Performance Of Light Gauge Steel Framed Residences

Light gauge steel framed system, which is one of new steel structures, has been on a rapidly increasing scale and has been used for low-rise residences widely in the world, but its research and application has just been on the stage of start-up in our country. In order to promote the application of light gauge steel framed system in residences, especially in multi-storey residences for our country, this paper makes a series of researches on the structural performance of light gauge steel framed system, and focuses on analyzing the seismic performance of this system. The innovation of simplified theoretical analysis, numerical analysis, design method analysis is emphasized.Aiming at the constructional characteristic of light gauge steel framed system, this paper explains the calculative principle for the system, and introduces the calculative formulas of the carrying capacities for members in the system. A method for determinating the buckling load and the allowable capacity of wall studs when considering the bracing effect from wallboard is specified. This method can be referred by designers and researchers.A simplified method for determining the lateral resistance of light gauge steel framed compound bearing walls which have many influencing factors and are difficult to be calculated theoretically is studied. The theoretical formulas for calculating the lateral resistance of the walls are conducted by using the principle of work and energy. And a compute program is developed by author. Comparing with experimental results, we can draw the conclusion that calculative results can represent the lateral resistance of the walls approximately, but there are some errors. Inaccurate values for connector parameters are the main reason causing the appearance of errors. Some advices are given by author for future researches. And this simplified method supplies a gap of the theoretical analysis method for compound bearing walls.To promote the application of light gauge steel framed system in seismic fortified areas, a finite element method is used to analyze the shear resistance, the hysteretic behavior, the energy dissipation behavior and the ductility of compound bearing walls under static and cyclic loading. In the finite element model, a nonlinear link element is used to model sheathing-to-framing connectors. And the link element is given a hysteretic model to respond the whole energy dissipation, stiffness degradation and "punching" load-deformation loops in the walls. To determine the characteristic parameters of the link element, a new method is put forward in this paper, that is numerical simulation by experimental results. Then the effects ofaspect ratio and screw spacing on the shear resistance and the hysteretic behavior of the walls are analyzed. Analytical results show that reducing screw spacing can improve the shear resistance and the hysteretic energy dissipation capacity of the walls.Based on the finite element model of compound bearing walls, this paper uses a simplified method to establish the planar analytical model for light gauge steel framed residences, and studies the time history response of the residences under horizontal earthquake. The important influencing parameter (screw spacing) is studied in detail. According to the analytical results, the applicable ranges of the residences when used in areas where the seismic fortification intensities are 7 and 8 are explored. This lays a foundation for promoting the application of light gauge steel framed system in multi-storey residences for our country.Based on above research results, a performance-based seismic design approach of light gauge steel framed system for multi-storey residences is put forward in this paper. The approach is applied to the design of light-gauge steel framed system for multi-storey residences according to the current Chinese Code for Seismic Design of Buildings. In terms of four different performance levels corresponding to frequent, occasional, infrequent and terribly infrequent earthquakes respectively, a performance-based seismic design of light-gauge steel framed system for multi-storey residences through a direct-displacement methodology is performed. As an application example, the displacement-based seismic design of a simple five-storey light-gauge steel framed residence is provided. Furthermore, we can draw the conclusion that light-gauge steel framed system is appropriate to be used in four or five-storey residences where the seismic fortification intensity is 7. This conclusion is consistent with the time-history analysis result.