弹性约束平面预应力钢桁架系统可靠性分析

Reliability Analysis of the Planar Prestressed Steel Structural System with Elastic Restraint

基于一次二阶矩法建立了平面索张拉预应力钢桁架任意单元失效模式的可靠性指标与验算点的迭代模型,并基于点估计法得到了整体结构失效概率的计算公式,其中任意单元随机内力统计特性—标准差则基于随机摄动理论确定,且考虑了任意弹性约束的影响.整体结构的基本随机参数包括折线索单元和桁架单元的截面面积(或综合刚度)、张拉钢索的预拉力、外荷载及约束刚度等.按照本文所建立的计算模型编制了相应的计算程序,对工程中常见的预应力钢桁架结构进行了分析,并对影响整体可靠性指标的有关参数进行了讨论,得到了有一定参考价值的结论.

Based on the first order second moment, the computational model of reliability index for each element failure mode is established, and the formula for calculating failure probability for overall structural system is further obtained using the point evaluation technique. The statistical characteristics of random internal forces of the structures with elastic restraint is obtained using random perturbation methods. The random parameters of overall system include areas of cross sections of all the elements, area of cables, pretension of cables, external forces and stiffness of elastic restraint. The computational model is programmed in VISUAL FORTRAN. Analysis is conducted on prestressed steel structures commonly found in engineering projects, and comments are made on some factors pertinent to the overall reliability indices. This research work is expected to serve as references that may help with designing the prestressed steel structural system.