大跨度连续梁桥悬臂施工整体抗倾覆稳定安全系数评估

为了评估连续梁桥在悬臂施工期间的安全性，提出了一种基于可靠度反分析理论的大跨度连续梁桥悬臂施工整体抗倾覆稳定安全系数计算方法。该方法可在给定目标可靠度指标和计入结构参数随机性的前提下，采用可靠度反分析理论，求解连续梁桥悬臂施工整体抗倾覆稳定安全系数。运用该方法计算了一座大跨度连续梁桥的抗倾覆稳定安全系数，并分析了参数敏感性，同时探讨了安全系数取值的合理性。计算结果表明：参数的随机性对连续梁桥悬臂施工阶段整体抗倾覆稳定安全系数影响较大，忽略参数随机性影响会导致过高估计整体抗倾覆稳定安全系数；应根据目标性能需求选择合理的安全系数；在悬臂施工中需要特别关注临时固结设施的合理性，避免挂篮和浇筑节段同时掉落，以保证结构在施工期间的抗倾覆稳定安全；随机变量分布类型对安全系数分析结果有较大影响，在实际施工过程中，可对实际变量参数进行抽样统计，确定合理的随机变量分布类型，以此计算得到的抗倾覆稳定安全系数更加符合实际工程需求；安全系数初始值的选取对该计算方法结果的准确性没有影响，只对结果的收敛速度有一定影响；推荐的可靠度反分析方法对基于目标可靠度指标确定抗倾覆稳定安全系数具有较好的适用性。

Safety Factors Assessment of Resistant Overturning Stability of Long-span Continuous Girder Bridges in Cantilever Construction

In order to estimate the safety of continuous girder bridges in the cantilever construction, a calculating method of safety factors of the resistant overturning stability of long-span continuous girder bridges in the cantilever construction was proposed based on the inverse reliability analysis theory. In the premise of the given target reliability indices and the randomness of structural parameters, safety factors of the resistant overturning stability of continuous girder bridges were solved by the inverse reliability analysis theory. Safety factors as well as the sensitivity of parameters of resistant overturning stability of long-span continuous girder bridges in the cantilever construction were analyzed by the proposed method. The rationality of safety factors of the longitudinal resistant overturning stability was discussed. The results show that the randomness of parameters has a major effect on safety factors of the resistant overturning stability of long-span continuous girder bridges in the cantilever construction, and ignoring the randomness of parameters will result in the overestimation of safety factors of the resistant overturning stability of long-span continuous girder bridges in the cantilever construction. The reasonable safety factors should be selected based on the target performance, and the rationality of interim consolidated facilities in the cantilever construction, as well as form traveler dropping, should be focused in order to assure the resistant overturning stability of long-span continuous girder bridges. The distribution type of the random variable has a great influence on safety factors. In the actual construction, the actual variable parameters should be sampled and statistically analyzed to determine a reasonable type of random variable distribution. Based on this, safety factors of resistant overturning stability will be more consistent with the actual situation. The choice of the initial safety factor has no influence on the accuracy of the result of the calculation method, and only has a little influence on the convergence rate of results. The inverse reliability analysis method proposed is well applicable to the determination of the safety factors of the resistant overturning stability based on target reliability indexes.