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铁路桥梁承受的运营动荷载很大,而且加载次数很频繁,因此,疲劳验算在铁路桥梁的设计中是很重要的部分。我国现行桥梁设计规范中,疲劳验算仍沿用国际长期采用的疲劳容许应力法。设计的假定状态和列车的运营情况脱节,设计中的作用力与抗力反映不了实际情况。根据这样规则设计出的桥梁,不能满足当前运输量日益发展的需要。为了设计方法的改革,本文主要介绍铁路钢桥疲劳可靠性的主要研究成果,其中包括疲劳荷载及标准荷载效应比频谱的制定,疲劳抗力的研究,疲劳验算方法及表达式,现有桥梁疲劳可靠度评估和新建桥梁的目标可靠度建议。采用这一新的理论进行疲劳检算不仅可以估计结构完成预定功能的概率,而且能平衡结构中每个构造细节的功能要求水平,对结构的安全与经济都有十分重要的意义。
Railway bridges bear heavy operational loads and loads are frequent, so fatigue checking is a very important part of the design of railway bridges. China’s current bridge design specifications, the fatigue test is still using the international long-term fatigue allowable stress method. The assumed state of the design is out of line with the operation of the train, and the actual forces and resistance in the design can not reflect the actual situation. The bridges designed on the basis of such rules can not meet the current needs of the current volume of transportation. In order to reform the design method, this paper mainly introduces the main research results of the fatigue reliability of railway steel bridges, including the formulation of fatigue load and standard load effect ratio spectrum, the study of fatigue resistance, fatigue checking method and expressions, the fatigue of existing bridges Degree Assessment and Target Reliability Recommendations for Newly Built Bridges. Using this new theory for fatigue checking not only can estimate the probability that a structure will perform a predetermined function, but also balances the functional requirements of each structural detail in a structure, which is of great significance to the structural safety and economy.