地下增层托换桩-柱置换节点薄弱区应力分析

Stress Analysis on Weak Area Generated in Pile-Column Replacement in Basement Extension

地下室下扩增层工程常需进行“桩变柱＂结构置换，承台节点成为关键部位。为分析节点薄弱区的应力变化状况，首先建立了一桩一柱承台节点的力学分析模型；然后采用有限元方法和单元生死技术，对某高层建筑在不同施工阶段的承台节点应力分布状况进行求解；最后根据求解结果分析薄弱区产生的原因及其应力变化规律。研究结果表明：当承台节点置换为梁柱节点时，核心区应力水平大幅增加；不同施工工序将影响核心区的应力路径。

The 'pile-to-column'structural replacement is usually required in basement extension project and the pile cap joint becomes a key part of the reconstruction.In order to analyze stress variation of weak area of pile cap joint,a mechanical analysis model for one-pile-one-column pile cap joints is established.Then,Finite Element Method and the element birth and death technology are utilized to solve stress distribution of pile cap joint in different construction phases of a high-rise building.Finally,causes of the weak area as well as its stress variation pattern are analyzed according to the solving result.The following conclusions are drawn through this study:stress level of core area increases significantly during the replacement beam-column joints;the stress path in the core area is affected by different construction steps.