Development of Fatigue Check Program of Highway Bridges

公路桥梁受到重载交通的影响，给桥梁次构件带来一定的疲劳问题。构件的重量和构件的重量都有所增加，特别是在日本1960年代的S和1970年代的S的经济快速增长期间和之后。与铁路桥梁相比，公路桥梁是传统的非疲劳设计，因为货车荷载对构件造成的应力范围相对较小。采用直方图记录仪对多座公路桥梁的服役应力进行了测试，并利用Miner累积损伤准则计算疲劳损伤。结果表明，公路桥梁主要构件的使用应力范围较小，存在的可能性很小。然而，在经历疲劳开裂的几个细节上，使用应力范围显示出较高的应力范围，因此剩余疲劳寿命较短。

Highway bridge are subjected to heavy truck traffics, which causes some fatigue problem to the secondary member of the bridges. Both the member and the weight of the trucks increased , especially during and after the rapid economic growth in Japan in 1960's and 1970's. The highway bridges were traditional not designed for fatigue because the truck loading caused relatively small stress range to the members, compared with the railroad bridges. However, the fatigue cracking were observed recently in many highway bridges, and assessment for fatigue seems necessary.Service stress measurement were carried out on several highway bridges by histogram recorder, and fatigue damages were computed using the Miner's cumulative damage rule. The result revealed that the service stress ranges in main members of the highway bridges were relatively small and a very little chances seemed to exist. However, the service stress ranges in several details which experienced fatigue crackings showed rather high stress ranges, and hence short remaining fatigue lives.