教学楼户外楼梯的空间地震效应及其加固措施

Spatial Earthquake Response and Strengthening of Outdoor Stairs in School Buildings

汶川地震震害调查中发现,楼梯斜板结构破坏较为严重,甚至楼梯板早于主体结构破坏出现。结合震害调查结果,针对目前中小学抗震鉴定中普遍存在的户外楼梯抗震问题,结合某中学教学楼抗震鉴定实例,讨论了楼梯斜板的空间刚度效应对整体结构抗震性能的影响。分析结果表明,楼梯斜板的空间刚度效应对整体结构抗震性能影响较大,不能忽略;楼梯斜板在地震作用下,表现为偏心受拉(压)构件,而不是原设计所认为的受弯构件,这也解释了汶川地震中楼梯间结构震害较重的原因。最后,提出了一个切实可行的楼梯斜板加固措施。

During Wenchuan earthquake,a lot of stairways have been destroyed,some of which damaged before the main structure was ruined.There are many problems about the seismic performance of outdoor stairways in many school buildings.Regarding to a specific seismic-appraisal project,considering the seismic damage investigation results,the influence of spatial stiffness effect of outdoor stairways on the structural seismic performance was studied.According to the analysis results,spatial stiffness effect of the stairways has an important influence on the seismic-resistance performance of the entire structure.This effect is often ignored in structural design.Under earthquake action,the stair-slab is an eccentrically-tensioned member rather than a bent member.It is the reason why seismic damage of stair-slab is serious during Wenchuan earthquake.Finally,an efficient retrofit scheme was proposed to strengthen the stair-slab.