非随机过程的地震激励下埋地压力管道的非概率可靠性分析

Non-probabilistic reliability analysis of buried pressure pipeline under non-random process earthquake excitation

在地震工程中,利用传统的随机过程模型来建立动态不确定荷载的随机过程模型,需要大量的时间历程实验样本。基于地震记录因受成本或实际因素限制导致的样本贫乏,且传统的随机过程的求解计算量巨大,提出了以非概率的集合理论凸方法为理论基础的非随机过程,以解决实际工程对地震荷载随机过程函数分布形式的灵敏问题;针对实际地震荷载的非平稳性随机性特征,结合区间模型和强度包络函数,建立了区间非平稳地震荷载模型;根据地面运动的时域非平稳特征,结合非随机过程振动理论,推导了埋地管道的动力响应;为了求解出的埋地管道在内压作用下的管道强度,采用了von-Mises第四强度理论,建立了非随机过程地震荷载下的埋地压力管道动力响应式;根据理论分析出的简化公式,结合非概率可靠性理论,针对某成品油管道进行了非概率可靠性实例分析。研究结果表明:在小样本情况下,利用凸模型理论可处理荷载的时变不确定性,可进行结构的非概率可靠性分析;这对只有小样本的实际工程的抗震可靠性分析具有指导作用,对建立地震激励下的结构的响应设计体系研究具有积极意义。

In the earthquake engineering,the traditional random process model has been used to establish the random process model for dynamic uncertain load,and it needs a large number of experimental samples of time history. Due to the lacking samples of seismic records caused by the restriction of cost or practical factors,and the traditional random process requires a large amount of calculation,a non-random process based on the non-probabilistic convex method of the set theory was proposed to solve the sensitive problem of the distribution form of random process functions for the seismic load in the practical engineering. Aiming at the non-stationary random features of the practical seismic load,an interval non-stationary seismic load model was established based on the interval model and the strength envelope function. According to the time-domain non-stationary characteristics of ground motion,the dynamic response of the buried pipeline was deduced combining with the non-random process vibration theory. To solve the strength of pipeline under the effect of internal pressure,the fourth strength theory of von-Mises was applied to establish the dynamic response formula of buried pressure pipeline under the nonrandom process seismic load. According to the simplified formula obtained by the theoretical analysis and combined with the non-probabilistic reliability theory,the case analysis of non-probabilistic reliability was carried out on a oil product pipeline.The results showed that in the case of a small sample,the convex model theory can be used to deal with the time-varying uncertainty of the load and carry out the non-probabilistic reliability analysis of the structure. It has a guiding role for the seismic reliability analysis of the practical engineering with only a small sample,and has positive significance for establishing thestructural response design system under the earthquake excitation.