基于规范公式的成层地基沉降模糊可靠度分析

Fuzzy Reliability Analysis of Layered Foundation Settlement Based on Standard Function

以规范公式为基础,提出地基沉降模糊可靠度分析的实用方法,即在功能函数中引入与规范规定沉降允许值相对应且能反映模糊特性的新随机变量,并将模糊运算转化为常规运算。该方法可同时考虑地基沉降的随机不定性和模糊不定性,得到了事件的模糊可靠度。通过实例分析,对比了本文方法和传统方法的结果,并进一步研究了荷载实际分布形式对地基沉降可靠性指标的影响。结果表明模糊可靠度分析得到的可靠性指标小于传统方法,荷载总值不变时可靠性指标随荷载比(活荷载效应与永久荷载效应的比值)增大而增大。

This paper proposed a practical fuzzy reliability analysis method for layered foundation settlement prediction. In this method, a new variable is introduced into the performance function and the statistic parameter of this variable is related to allowable settlement value in code. This method considers both the randomness and the fuzzification. Compared with the traditional reliability analysis method, the result indicates reliability index calculated by this method is smaller than that by traditional method.Furthermore, the influence of the ratio of the variable load to the dead load (i.e. load ratio) on reliability index is investigated.