基于一次二阶矩法渡槽系统模糊可靠度分析

Fuzzy Reliability Analysis of Aqueduct System Based on First Order Second Moment Method

为了更合理地评价钢筋混凝土渡槽结构在正常使用极限状态下的安全可靠性,针对在役钢筋混凝土渡槽结构,考虑影响其结构稳定性因素的随机性及模糊性,基于一次二阶矩法建立了渡槽结构底板与侧墙抗裂随机模糊可靠度模型,编制了相应的程序,并利用PNET法针对某工程实例进行了系统模糊可靠度分析。结果表明:在相同条件下,中心点法和验算点法可靠性指标计算结果与建立的模糊可靠度方法基本一致,验证了模糊可靠度方法的正确性;在不同条件下,渡槽系统可靠性指标随着考虑相关变量因素的增多而减小,这与实际情况相符,即考虑变量的随机性与模糊性更接近于结构真实情况,所得解更为合理;传统可靠度计算方法所得抗裂能力可靠性指标结果偏大,高估了渡槽结构整体的可靠性,采用传统方法得到的极限状态设计值偏于不安全,实际工程中应考虑影响因素的随机模糊性。

In order to evaluate the safety and reliability of reinforced concrete aqueduct under the limit state of normal use more reasonably, this paper established the fuzzy random anti-cracking of the floor and side wall of the aqueduct structure based on the first-order second-moment method, considering the randomness and fuzziness of the factors affecting the structural stability of the existing reinforced concrete aqueduct structure. The reliability model and the corresponding program were compiled, and the fuzzy reliability of the system was measured by the PNET method. The results need to show that under the same conditions, the reliability indices of the center point method and the checking point method are basically the same as those of the present method, which verifies the correctness of the proposed method. The randomness and fuzziness are closer to the real situation of the structure, and the solution is more economical. The reliability index of crack resistance obtained by traditional reliability calculation method is too large, which overestimates the reliability of aqueduct structure. The design value of the limit state obtained by the traditional method is unsafe. The random fuzziness of influencing factors should be examined in practical engineering.