已建砌体结构悬挑楼梯间拆除方法的分析

Demolition of cantilevered staircase in existing masonry structure

在将20世纪建造砌体结构的悬挑楼梯间改造为现浇楼梯间的施工过程中,若全部拆除原有悬挑楼梯间,将造成相邻山墙的计算高厚比很大,不满足规范要求,给施工带来安全隐患。针对于此,提出两种拆除方法:(1)保留休息平台、拆除悬挑踏步板;(2)现浇楼层处梯柱及梯梁、保留休息平台、拆除悬挑踏步板;然后现浇梯板、拆除休息平台、现浇休息平台。通过Sap2000对一实际工程进行线性屈曲、非线性静力分析,表明这两种方法都可以有效减小山墙的计算高厚比;方法(1)适用于建筑高度不大的楼梯间山墙;方法(2)适用于建筑高度较大的楼梯间山墙。

In renovatinga masonry structure with cantilevered stair room built in the last century into one with cast-in-place stairway,demolishing the entire stairway could result in a large depththickness ratio beyond standards and leave safety risks. In view of this problem,two methods are proposed.（1） To remove the cantilevered stair treads while retain the rest platform;（2） To build castin-situ ladder stanchion and ladder beam,retain the rest platform and demolish the cantilevered stair treads; whenthe ladder treads are completed,new rest platforms are casted after removing the old ones. These two methods are able to allow the slenderness ratio of gable meets the norms,thus to ensure the safety of construction. A linear buckling and nonlinear static analysis of a practical project by Sap2000 shows that both methods can effectively reduce the depth-thickness ratio ofgable. To be specific,the first method suits the buildings with low gable,while the second method suits the buildings with high gable.