考虑损伤状态阈值模糊性的重力坝地震易损性分析

由于结构损伤状态的演变是一个逐渐过渡的过程,以及分析认知的模糊性,重力坝地震损伤状态的阈值具有模糊性。本文提出了描述重力坝损伤状态阈值模糊性的数学模型,结合坝与地基系统的非线性有限元地震动力分析和Hariri-Ardebili的损伤状态量化方法,提出了重力坝模糊地震易损性分析方法。将提出的方法应用于Pine Flat重力坝,研究了隶属度函数形式和损伤状态阈值模糊区间的大小对Pine Flat重力坝地震易损性的影响。结果表明,损伤状态阈值模糊区间的大小对Pine Flat重力坝地震易损性的影响较大,而隶属度函数形式的影响较小。损伤状态阈值的模糊性导致Pine Flat重力坝轻度损伤状态的超越概率明显增加,而接近倒塌损伤状态的超越概率有所降低。因此,在重力坝地震易损性分析中应该考虑损伤状态阈值模糊性的影响。

Seismic Fragility Analysis of Gravity Dams Considering the Fuzziness of Damage States Thresholds

Since the evolution of the structural damage states is a gradual transitional process and the fuzziness of cognition, the thresholds of damage states of the gravity dams are fuzzy, which will affect the evaluation results of damage states of gravity dams. Fuzzy intervals of damage states thresholds and construction principles of membership function for damage indexes were proposed, and a mathematical model describing the fuzziness of damage states thresholds of gravity dam was built. Based on the nonlinear finite element dynamic analysis of dam-foundation system, Hariri-Ardebili''s quantitative method and the proposed mathematical model, a methodology for fuzzy seismic fragility analysis of gravity dams was proposed. Pine Flat gravity dam was used as a setting for numerical simulations. The 60 seismic waves were selected from ground motion database for incremental dynamic analysis of Pine Flat gravity dam. The damage indexes under different seismic inputs were calculated and the corresponding damage states were defined. The influence of the types of membership function and the sizes of fuzzy intervals of damage states thresholds on seismic fragility was investigated. The results showed that the types of membership function had little influence on seismic fragility of Pine Flat gravity dam, while the influence of sizes of fuzzy intervals on seismic fragility curves was obvious. Due to the distribution characteristics of damage indexes, the fuzziness of the damage states thresholds led to a significant increase in the probability of exceeding of Slight damage, while the probability of exceeding of near collapse decreased. Therefore, the influence of fuzziness of damage states thresholds should be considered in seismic fragility analysis of gravity dams.