基于断裂力学理论的钢桥疲劳可靠性评估

为了研究钢结构桥梁的疲劳可靠性,使得钢桥在可接受的风险水平下工作.基于断裂力学理论和可靠性分析方法,建立了适用于钢桥的断裂疲劳可靠性模型,同时对模型中的初始裂纹长度a0、临界裂纹长度ac以及疲劳裂纹扩展参数C和m等相关参数进行了分析,并通过可靠性分析方法确定钢桥构件的疲劳可靠度.将该模型应用于一座实际桥梁,通过可靠性理论中的JC法获得了该桥主要构件横梁和下弦杆的疲劳可靠度随累积应力循环次数的变化规律,为该桥在一定的目标可靠指标下进行服役提供了理论依据.

Fracture Mechanics Approach Based Fatigue Reliability Assessment on Steel Bridges

A fatigue reliability model based on fracture mechanics approach is presented to estimate the fatigue reliability of steel bridges, so as to make the steel bridges serve at an acceptable risk level. Related variables including the initial crack size, a0, the critical crack size,ac, and the fatigue crack growth parameters, C and m, in the limit state function are evaluated. Thus, the fatigue reliabilities of steel bridges' components and details can be achieved using different reliability calculation methods. The model is applied to a real steel bridge, and primary members including the crossbeam and the lower string of the bridge are evaluated. The principle of fatigue reliability associated with stress cycle accumulation is achieved by JC reliability method, which can be the theory basis for the bridge to serve with a certain target reliability index.