摘要
The R F first order second moment method will produce more error for calculating the reliability of welded engineering pipe structures when the failure function is seriously nonlinear and the random variables don′t serve as normal distribution. In order to increase the computing accuracy of reliability, an improved FOSM method is used for calculating the failure probability of welded pipes with flaws in this paper. Because of solving the problems of the linear expansion of failure function at the failure point and constructing equivalent normal variables, the new algorithm can greatly improve the calculating accuracy of probability of the welded pipes with cracks. The examples show that this method is simple, efficient and accurate for reliability safety assessment of the welded pipes with cracks. It can save more time than the Monte Carlo method does, so that the improved FOSM method is recommended for engineering reliability safety assessment of the welded pipes with flaws.
在对工程焊接管道结构的缺陷进行可靠性安全评定工作中,如果失效函数的非线性程度较严重和随机变量不服从正态分布,利用R-F一次二阶矩(FOSM)方法计算结构的可靠度会带来较大的计算误差。本文将改善FOSM方法用于含缺陷焊接管道的失效概率计算。由于该方法合理解决非线性失效函数在失效点的线性展开及非正态随机变量的当量正态化,使焊接管道失效概率的计算精度大大提高。实际算例表明,该方法用于含缺陷焊接管道可靠性安全评定简单、有效、准确。与Monte Carlo 计算方法相比,其可大大降低计算量。
