非完全相关荷载下钢筋混凝土框架结构体系可靠度分析

目前框架结构体系可靠度分析大多是在荷载完全相关的假定下完成的,对于非完全相关荷载作用下的体系可靠度研究则鲜有涉及,对于非理想弹塑性或弹脆性的结构尤其如此.本文在随机系统分析的概率密度演化理论的基础上,结合结构非线性全过程分析的位移控制算法,推导了基于归一化位移参数的结构非线性发展概率密度演化方程和承载力裕度的概率密度演化方程.采用纤维梁柱单元进行非线性分析,研究了钢筋混凝土框架结构在非完全相关荷载下的体系可靠度,并与Monte Carlo法进行了对比分析,证明了文中建议方法的可行性.基于文中方法,分析了荷载相关性对可靠度的影响,计算结果表明,荷载相关性对体系可靠度有比较明显的影响.

System reliability analysis of RC frame with non-perfect correlated loads

Currently, the assumption of perfect correlation is usually taken for the governing loads in system reliability analysis of frame structures. Little attention has been paid to non-perfect correlation research, especially for imperfect elastoplastic structures and imperfect elastobrittle structures. In the present paper, based on the recently proposed probability density evolution method (PDEM), the probability density evolution equations for the nonlinear evolution process of frames and for the margin capacity with loading parameter as time variables are firstly derived. Then, adopting the structural nonlinear analysis based on the fiber beam-column element, the system reliability of RC frames subjected to non-perfect correlated loads was calculated. Finally, the reliability of a 2-story 2-bay RC frame involving random parameters was numerically investigated. The results show that the influence of load correlation on reliability analysis cannot be neglected. Furthermore, in comparison to the Monte Carlo simulation, the proposed method is accurate and more efficient for the reliability analysis of RC frames with non-perfect correlated loads.