移动模架施工PC连续梁桥悬臂段箱梁空间效应不利影响及其防治措施

预应力混凝土连续梁桥在采用移动模架施工过程中,悬臂段梁体承受的多种施工荷载会产生不利的空间效应,致使最前端梁体底板开裂。通过建立空间有限元悬臂梁节段线弹性模型来模拟实际结构空间受力状态,进行箱梁悬臂段的空间效应分析,揭示底板裂缝的成因。结合工程实践中发现的问题,提出了转移底模锚点、设置端横隔梁及模架后支点后移等措施,可供类似工程借鉴。

Impact Analysis and Crack Prevention for PC Continuous Box Girder Arising from Movable Scaffolding System

When movable scaffolding system(MSS) is adopted in the construction of continuous girders,the joints are usually set at(l/5),where the bending moment of dead load is generally the smallest.So the part of the girders that extend piers act as cantilevers,where the load transform and construction stress are very complex and cracks might be found in the floor of the box girder.A 3-D finite model is created to simulate and analyze the structure's loading condition.And the mechanism of the floor cracks is brought to light.Also,some practical methods of shifting the anchoring location,setting cross diaphram and backward adjustment of MSS are bringing up for(preventing) the girder form cracking,which has been adopted in practice.