混凝土浇筑期考虑节点搭接缺陷的模板支架概率极限状态设计

Probabilistic limit state design of falsework considering joint lap defects during concrete pouring period

为了确保混凝土浇筑期模板支架的安全性,基于可靠度理论,提出了考虑节点搭接缺陷的概率极限状态设计方法.选取具有代表性的工地进行现场调研,得到模板支架中节点搭接缺陷的发生规律及统计特性,对节点搭接缺陷进行数值模拟,分析了施工荷载以及模板支架跨数对荷载效应系数的影响,分别建立了考虑与不考虑节点搭接缺陷时的概率极限状态设计表达式,并将所得结果与建筑施工扣件式钢管脚手架安全技术规范所得的可靠度指标进行比较.结果表明:所建立的非线性有限元模型在模拟节点搭接缺陷方面具有较高的精度;施工荷载对荷载效应系数变异性的影响远大于支架跨数的影响;基于所提设计方法得到的可靠度指标与目标可靠度指标具有最佳一致性.

To ensure the safety of a falsework during the concrete pouring period,based on the reliability theory,a probabilistic limit state design method considering joint lap defects was proposed.The representative construction sites were selected for field investigation.The occurrence rules and the statistical characteristics of the joint lap defects in the falsework were obtained.The joint lap defects were simulated numerically.The influence of the construction load and the number of the falsework spans on the load effect coefficient was analyzed.The probabilistic limit state design expressions with and without joint lap defects were established,respectively,and the results were compared with the reliability index obtained by the technical code for safety steel tubular scaffold with couplers in construction.The results show that the nonlinear finite element model has high accuracy in simulating joint lap defects.The influence of the construction load on the load effect coefficient is far greater than that of the number of the falsework spans.The reliability index obtained by the proposed design method has the best consistency with the target reliability index.