交通車両による振動の影響を考慮した道路橋の信頼性工学的疲労損傷予測(<特集>信頼性工学)

概要

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The effect of the scatter of fatigue life data and the effect of traffic-induced vibration of highway bridges on evaluations of their fatigue failure probability have been investigated through a reliability approach with the dynamic response analysis. Highway bridges are subjected to a large number of repeated load cycles which have random variable amplitudes during their service lives. Therefore, the prediction of their fatigue damage is popularly obtained by Miner's rule under which the damage accumulates linearly. In such a case, a cumulative damage D= Σ(n_i/N_i) must be treated as a random variable with such a kind of probability function as Weibull distribution because of the scatter of the fatigue life N_i under the constant amplitude stress Δσ_i, in which n_i is the number of stress reversals at a level Δσ_i. This paper describes a simple method for obtaining the probability density function of the cumulative damage given by the sum of (n_i/N_i) by the use of the mathematical theorem that the probability density of the sum of two independent random variables equals the convolution of their densities. Following this procedure, the fatigue failure probability can be obtained by calculating the probability P{D>1}. Furthermore, the fatigue failure probability of a highway bridge subjected to a moving vehicle is evaluated by the proposed method based on the dynamic response analysis of the bridge.
1998-12-15