The stairs were badly damaged in all previous earthquakes and lost the escape function which indicates that the seismic design has defects.Based on the finite element program ANSYS,a RC frame structure model was developed,which is respectively provided with beam-type stairs,plate stairs,and cantilevered stairs,and their seismic responses were analyzed under El-Centro,Taft and ASW wave.The results show that the presence of stairs will affect the frequency and vibration mode of the overall structure,and change their stiffness,and the influence will be reduced successively from the beam-type stairs,plate stairs to cantilevered stairs.The contribution of the stairs to the torsional rigidity of the structure is not significant,but the influence of the stairs on the lateral stiffness of the structure is mainly concentrated in several layers of the bottom of the structure.With the increase of the floor number,the influence is gradually reduced,and the influence of each layer stairs is mainly concentrated on the layer of the structure.The interaction between stairs and their structure is related to the form of stairs and the connection between them.Their connections are better,the in-teraction is stronger,and vice versa.The contribution of stairs to structural stiffness cannot be neglected,and the seismic load on the staircases themselves also cannot be neglected.In the design of the stairs,the loading should be assembled according to the integral seismic shear force,and then the bearing capacity of the staircase is calculated,otherwise,the stairs would easily become the first line of defense under the action of an earthquake,which would be destroyed firstly.%通过借助ANSYS有限元程序,分别建立带梁式楼梯 、板式楼梯 、悬挑楼梯的框架结构模型,分析其在El Centro、Taft和某人工波ASW作用下的地震反应,为抗震设计提供参考.研究结果表明:楼梯的存在将会影响整体结构的频率和振型,改变结构的刚度,其影响从梁式楼梯 、板式楼梯,向悬挑楼梯依次减小;楼梯对结构抗扭刚度的贡献并不显著,而对结构抗侧刚度的影响主要集中在结构底部几层,随着楼层数增加,影响逐渐减小,并且每层楼梯的影响主要集中于本层结构;楼梯与结构的相互影响作用与楼梯的形式和二者的连接方式有关,二者连接强,则相互作用强,反之亦反;楼梯对结构刚度增大的贡献不可忽略,自身所承受的地震作用同样不可忽略,楼梯设计中应按整体计算的地震剪力进行荷载组合,然后进行承载力计算,否则楼梯极易成为地震作用下的第一道防线而首先发生破坏.
展开▼
