Analysis Research On Impact Of Stringer-type Stairs To Seismic Performance Of Steel-frame Structure

As an important evacuation passageway, The stair plays an important role in earthquake disaster prevention.At present,the design of stair is separated from the main structure.In this way,neither consider the interaction of stairs and the main structure under earthquake action,nor consider the effect of earthquake on stair members.All previous earthquake disasters show that,the traditional design method has disadvantages.It has caused more and more attention in structural engineering field.For concrete stairs,national codes and atlases related to calculation method and construction measures have been released.But the research in steel stairs is ignored.In this paper,we study the impact of stringer-type stairs to seismic performance of steel-frame structure.In order to study the impact of stringer-type stairs to seismic performance of steel-frame structure,we design two frame models.One model is a frame without stairs,only considering the effect of dead load and live load to simulate the seismic analysis does not consider the stairs.Another one is a frame with stairs to simulate the seismic analysis does consider the stairs.Then we study the models with modal analysis,response spectrum analysis and pushover analysis in SAP2000,comparing the dynamic performance and elastoplasticity performance.Based on above study,this paper preliminary get the following conclusions.Except dead load and live load,the leading effect to steel frame of stairs is that the stairs increase the stiffness of steel-frame structure.The stairs also change internal force of the vertical members of frames under earthquake action,especially for the columns and beams with stair members,which is very harmful to structures.The stairs work as a brace under earthquake action.The axial force is so large that cannot be ignored.The stairs designed with traditional method can’t meet the demand of the earthquake.The impact of stair on seismic performance of steel-frame structure is greatest along the stairs and the impact of one story at the bottom is greater than the else stories.