STIFFNESS ANALYSIS OF STAIRS TOGETHER WITH FRAME STRUCTURE BY D-METHOD

Many stairs of frame structure in wenchuan earthquake destroyed seriously,resulting in mass casualties.Research on earthquake damage found that diagonal bracing could not be ignored.The newly revised GB 500112010 Code for Seismic Design of Building pointed that the impact of stairs should be considered in calculating,so D-method was used for calculating simplified model with stairs in order to amend lateral stiffness of structure and force of stairs.Comparing results of analysis method with PKPM(08),it could be Proved that lateral stiffness considering stairs was greater than the one without taking account of stairs,and typical components of stairs had different force results between earthquake action and the those with considering gravity loads.It was proposed that components of stairs should be designed considering earthquake action;stiffness should be calculated considering effect of stairs.