The Dynamic Impact On The Structure Of The Staircase And The Countermeasure Research

The staircase is vertical transport corridors of the building, and the only way to evacuatethe people when the earthquake happened, but in recent years the damage survey found thatvarious forms of stairs damage appear when the earthquake occurred, including stair boardsbroken, platforms board broken, the platform beams destruction, and stairwell wallsdestruction, and even parts of the stairs collapsed because of damage and blocked the passageof people escape. At present, due to lack of attention in the design of building structures, thedesign of framework and the main structure is carried out separately, and did not consider theimpact of the earthquake on them, nor to consider its impact on the main structure, but we canseen from the earthquake that the impact study to consider participating in the overallstructure of the stairs performance is meaningful. In this context, this paper takes a6-storyframe structure for the study, the main work done and conclusions are as follows:(1) Use SAP2000software to set up two frame model that without considering theestablishment of a staircase and consider, its modal analysis results show that, considering thestairs participation model cycle decreased, the first-order cycle reduced by7.15%; considerthe stairs participation model first mode to reverse modes, regardless of modal participation ofstairs translational modes, indicating participation of stairs makes structural stiffness and massdistribution have changed;(2)For the two models of the response spectrum analysis, the results showed that themodel considered the participation stairs compared the staircase model does not consideredparticipating,the displacement in the Y direction that of along the stairs to reduce the degreeof3%~10%, X direction that Vertical the stairs to reduce the degree of0to1%，the baseshear in the Y direction is increase9.04%, X direction is increased to3.12%, indicatingConsider the stairs in a greater impact on the structure of the Y direction;(3) Carried out the study of the members of the stairs in case of seismic internalforces,and found that stair components under earthquake force situation is complex, thedestroy of staircase column is mainly caused by the huge column end moment, the destroy ofplatforms and platform plate girder was caused by shear pull;(4) In order to reduce the adverse effects on the structure of the staircase, this paper gavetwo designs that Stairway separated from the frame, one for Staircase column disconnectwhich means that set up another Staircase column to support platform beam column instead ofthe platform beam is supported directly in the frame beam column that near the framecolumn; the second is stairs board Breakaway, stairboards off the bench is the board and the rest is provided at an isolated platform connecting the sliding layer, then carried on modalanalysis and response spectrum analysis of the two kinds of model, the results showed that thecycle of stairs board Breakaway modal compared Staircase column disconnect modal islager2%, while both of the modal are larger than the model considering the stairs, the orderappeared is the bench plate off than large staircase column model cycle model cycle off about,translational modes appear in the order also different, in column Y displacement ladderstructure than to disconnect the bench plate off of large structures, X displacement of twolittle change in the structure of the base shear staircase column disconnected structure than thebench plate off the big Y7.53%, X to the big0.7percent, while the ratio of the base shearstructure model no stairs, which meant that the separation of the stairs with the main stairs canreduce the adverse impact on the structure to some extent and the second case is better;(5) The above four models of elastic time-history analysis, seismic waves in the stairs ofthe structure has a seismic effect amplification, which supports the impact can not be ignored;consider staircase structure of the model than the base shearAfter the staircase structuremodel does not consider the largest increase, bench boards off the structural model and thestructural model staircase column base shear off a slight increase structural model withoutconsidering the stairs, so take structural measures can greatly reduce the stair staircasestructure Overall adverse effects.