混凝土结构温差收缩效应分析计算

Analysis and calculation of temperature variation and shrinkage effects on RC building structures

迄今为止,国内外尚未能给出钢筋混凝土结构温差收缩效应合理解。研究提出考虑混凝土徐变收缩时效特性,考虑地基或桩基有限约束刚度,考虑带后浇带结构生成过程的施工模拟和考虑结构施工至使用生命全过程最不利温差取值的计算钢筋混凝土结构温差收缩效应的新方法。典型算例(平面500m×100m、双向柱网10m、6层现浇钢筋混凝土框架结构)计算分析结果表明,以往分析计算方法夸大了基础约束刚度,未按结构施工构成实际情况选取所经历的最不利温度场,未考虑混凝土收缩应变的不利影响,也未考虑混凝土徐变的有利影响,放大了底部结构应力,缩小了上部结构应力。新方法揭示的结构温差收缩效应比较合理准确,对大体量钢筋混凝土建筑结构设计有重要参考价值。

Currently there is no reasonable solution for temperature variation and shrinkage effects on RC building structures. A new method is presented, which takes into account of the concrete creep and transient shrinkage properties, the limited restraint stiffness of pile or foundation, the construction sequence including the post casting strips, and the most adverse temperature variations in the life of the building structure from construction to usage. The result of analysis and calculation of a typical project example （ 100 m × 500 m plane, 10 m column spacing, 6 story RC frame structure） shows that the traditional methods overestimated the foundation restraint stiffness as fixed end, adopted the temperature variations without considering the structure framing process in construction, and neglected the concrete creep and shrinkage properties, causing that the stresses in the lower structure enhanced and the stresses in the upper structure reduced, whereas the new method explores those effects reasonably and is valuable for design, especially for large RC building structures.