Analysis Of Seismic Performance Of Frame Structure With Stairs And Stairs Reduce Support Effect

The frame structure is a very widely used structure in the multi-storey reinforced concrete buildings.In this structure,stairs and main structure are often connected through the way of integral casting,and form a strong restraint effect between the two.With the seismic action,the gangboard with considerable stiffness will have larger deformation with the frame,leading to the quite large interaction of stairs and frames,thus not only the stairs are easy to be damaged,but also the seismic capacity of the frame structure will have a certain degree of weakening.Through the investigation and analysis on the site of Wenchuan earthquake,the stairs damage in the frame is most serious,and the stairs are often destroyed first.Reducing the constraints of stairs and frames can reduce the interaction of stairs and frames in the earthquake.Based on this idea,we can have the drop and support design to reduce the adverse effects of this interaction on stairs and seismic capacity of frame.In this thesis,10 of the 6-layers reinforced concrete frame structure models are established by SAP2000.They are 1 CKJ model of pure frame structure(without stairs),1 frame structure model with plate stairs(model B without having the drop and support design),and 8 frame structure models with drop and support stairs.The main research contents are as follows:(Ⅰ)Establish each model with SAP2000,then calculate the natural vibration mode and cycle of each model,and understand the contribution of different types of stairs to the stiffness of frame structure by analyzing the natural vibration period of each model.(Ⅱ)Respectively have spectrum analysis and linear time history analysis of each model under frequent encounter of earthquake,and check the structural elastic interlayer displacement angle.The interlaminar shear,the internal force of frame columns at staircase and internal force of frame beam and gangboard,and the additional damping ratio of energy dissipation support are calculated and analyzed.(Ⅲ)Respectively have the nonlinear time history analysis of each model under rare encounter of earthquake.Calculate the horizontal elastic and plastic deformation of the model interlayer displacement angle,interlayer displacement,peak displacement and sliding support and energy dissipation support,and draw the hysteresis curve of energy dissipation support.(Ⅳ)By Pushover analysis of each model,the capacity curve and performance point of each model are calculated.The yield order of each model is analyzed by observing the development of plastic hinge of each model.Thus the structure and the state of component of models in the performance points of small earthquake,medium earthquake and strong earthquake are evaluated.By the contrastive analysis of the 9 frame structure model with stairs and CKJ model,the degree of influence of the 9 stairs on the seismic performance of the frame structure can be understood.According to the contrastive analysis results of 8 model with drop and support stairs and model B,the drop and support effect of these 8 stairs can be evaluated.Therefore,the research of this thesis can provide reference for the designer to design the drop and support stairs so as to improve the seismic performance of frame structure,which is of good engineering practical significance.