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近年来,我国有大批桥梁得以新建。与此同时,日益增加的车辆荷载使得在役桥梁面临着更大的服役风险。在已有研究中,桥梁结构的可靠度评估将车载随机过程看作平稳泊松过程,且假定荷载效应概率模型在评估期内独立同分布。历史数据表明,我国的汽车荷载存在明显的逐年增加的趋势,随时间不再服从同一分布,已有方法也不再适用。为此,该文改进了已有方法,提出了考虑非平稳车载过程的在役桥梁时变可靠度评估新方法。算例表明,改进的方法简便易行,结果准确。已有方法可看作是该文改进方法的特例。随后,利用这一方法研究了结构可靠度对车载随机过程参数的敏感性。结果表明,车载随机过程参数对结构可靠度的影响显著。在20年的评估期内,均值每年增加1.1%或标准差每年增加1.3%,都会造成结构的失效概率增大两倍。
In recent years, a large number of bridges have been built in our country. In the meantime, the increasing load of vehicles makes the existing service bridges more exposed to service risks. In previous studies, the reliability assessment of bridge structures regards the on-board stochastic process as a stationary Poisson process, and assumes that the load effect probability models are independently and identically distributed during the evaluation period. Historical data shows that there is a clear trend of increasing car load in our country, no longer obeying the same distribution over time, and the existing methods are no longer applicable. To this end, the paper improves the existing methods and proposes a new method to evaluate the time-varying reliability of existing bridges considering non-stationary vehicle-mounted processes. The example shows that the improved method is simple and accurate and the result is accurate. The existing method can be seen as a special case of the improved method. Subsequently, this method is used to study the sensitivity of structural reliability to on-board random process parameters. The results show that the on-board stochastic process parameters have a significant impact on the structural reliability. During the 20-year evaluation period, a mean annual increase of 1.1% or an increase of 1.3% in standard deviation each year will result in a doubling of the probability of structural failure.