The Structural Influencing Coefficient And Displacement Amplification Factor In Multi-story Moment Resisting Steel Frames

Large earthquake disaster analysis and experimental research indicate that building structure can enter elastic-plasticity in strong motion earthquake.Utilizing ductility of structure,the major seismic codes reduce elastic force of design intensity by the structural influencing coefficient to get design earthquake action in structural design.So,the security and economy of structure design lie on the value of structural influencing coefficient.The single structural influencing coefficient is nowadays adopted by currently Code for seismic design of buildings in all structural systems built by different materials in our country.So the good ductility and energy-dissipating capability of steel structure cannot be fully reflected according to this kind of method,and it is necessary to the structural influencing coefficient to carry on systematic research.Firstly,in order to obtain the load versus displacement curve of moment-resisting frame (MRF) under horizontal force and verify finite element analysis,the static pushover test was conducted on a moment-resisting frame of three-story and one-bay.The result of test showed MRF has good ductility performance,and result of finite element simulation have a good agreement with those of experiment.Secondly,based on the static Pushover analysis,the structural influencing coefficient and displacement amplification factor in multi-story moment-resisting steel frames are carried on systematic analysis.Adopting the model of uniform load and triangular load separately,MRFs of different story numbers and bay numbers are analyzed by static Pushover analytical method,and the global capacity envelopes are obtained.Then,through a method for establishing the inelastic demand spectrum of design intensity and rare intensity based on elastic spectrum of seismic design code for buildings,the structural target displacement of design intensity and rare intensity are estimated by improved capacity spectrum method.The corresponding structural ductility reduction factor,the overstrength factor,the structural influencing coefficient and displacement amplification factor are determined.Meanwhile,the impact on every coefficient of the mode of load,story numbers and span numbers are discussed.In addition,based on incremental dynamic analysis(IDA),the structural influencing coefficient and displacement amplification factor in multi-story moment-resisting steel frames are studied.According to the combination of non-linear shell element and beam element,inelastic time history are performed on steel frames to get the base shear versus top displacement envelope curve.Then,the structural influencing coefficient and displacement amplification factor are calculated and compared with the analysis result of Pushover method.All in all,the structural influencing coefficient and displacement amplification factor in multi-story moment-resisting steel frames are analyzed systematically,which might be useful for revising design code,guiding engineering design and lay the good foundation for further research seismic behavior of moment-resisting steel frames.