考虑弯剪耦合作用的梁桥可靠度评估

Beam Bridges Reliability Assessment considering Moment-shear Coupling Effect

摘要:

梁桥在运营中同时承受弯矩与剪力效应，其弯曲与剪切抗力亦互为影响，在役梁桥的评估需考虑弯剪耦合作用。本文将抗力与效应由一元随机变量拓展成二元随机变量，引入美国AASHTO规范采用的修正压力场理论（MCFT），建立了弯剪耦合抗力与弯剪复合效应的概率模型，提出了考虑弯剪耦合作用的可靠度评估方法。算例分析表明，对于复合效应中弯矩、剪切分量都较大的截面，其失效机制是弯剪耦合破坏，传统方法结果偏不安全，有必要采用考虑弯剪耦合作用的可靠度评估方法。

Abstract:

Beam bridges in the operation bear both moment effect and shear effect at the same time, and their moment and shear resistances also affect each other. The assessment of existing Beam bridges needs to consider moment-shear coupling effect. The resistance and effect variables were expanded from unary random variables into binary random variables in the paper. Based on the modified compression field theory (MCFT) adopted in AASHTO LRFD design specification, the probability models of moment-shear coupling resistance and effect were established. A new reliability assessment method was proposed to consider moment-shear coupling effect. The example analysis shows that: for the cross-section bearing both larger moment and shear effect component, the failure mechanism is the moment-shear coupling failure, the traditional method results in unsafe conclusion, and it is necessary to consider the moment-shear coupling effect during reliability assessment.