Structural Influence Factors Of Concentrically K-braced Steel Frames

Generally, structures will enter a region of non-linear behavior in event of severe ground motions with dissipative ability, which earthquake action is obviously different from single-degree-of-freedom system. The inelastic seismic response of structures were influenced by many factors, such as period of structures, ductility and damping etc. In practice, in order to account synthetically for the influence factors and convert the inelastic seismic design method into the pseudo-static method, which is easily accepted by engineers, the structural influence factors is commonly used in seismic design of structures. The structural influence factors are not only the key factors for determining seismic action in force-based seismic design, but also the key parameters to deduce the inelastic response spectra in performance-based seismic design. Seismic design are not only intermediate-earthquake design for applicable code, but also multilevel design intensity performance-based seismic design. It is necessary to consider the ductility while carry on analyzing the earthquake-action, which is closely relative to seismic capability and ductility. The base reaction of structure is low for high ductility. As we known, steel structures obviously have better ductility, deformation ability and dissipative ability than other structural styles. It has taken some contents of medium-high steel structures in the current Code for Seismic Design of Building(GB50011-2001), but it has not been embodied in the current seismic code with regard to the aspect of the value of earthquake action and dutility. Considering the damping ratio of elastic stage will exaggerate the value of earthquake action of steel structures. The structural influence factors of seismic design code for most countries depend on earthquake disaster experience without enough theoretical supporting.Structural influence factors of steel structure have not been studied, which fall behind foreign Standard and Codes. This paper has given the values of the structural influence factors for several K-braced steel frames. Structural influence factors including ductility and overstrength of K-braced frames were evaluated by performing pushover analysis of model structures with various stories, span lengths, spans and earthquake intensity by means of SAP2000. For different steel braced frames, the structural influence factors was found to be different, Hope that paper can provide reference for the revision of earthquake-resistant design code.