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当前,随着交通运输量的大幅度增长,车载和车流量越来越大,因而有相当一部分公路桥梁已满足不了使用上的需要,这是世界各国所面临的严峻问题。美国曾对51.4万座公路桥梁作了调查,其中约20％的桥梁需立即大修或降低使用标准,约20％的桥梁桥面太窄、功能老化或承载能力偏低。如果对那些不适应现代交通运输要求的旧桥拆除重建,这不仅耗资巨大,而且在时间上也不允许。旧桥的老化、承载能力降低这一问题,已引起各国的极大关
At present, with the substantial increase of traffic volume and the increasing traffic volume of vehicles and vehicles, a considerable number of highway bridges can not meet the needs of use. This is a serious problem facing all countries in the world. In the United States, a survey of 514,000 road bridges was conducted. Approximately 20% of bridges require immediate overhaul or lowering of service standards. About 20% of bridge bridges are too narrow, functional aging or carrying capacity is low. Demolition and reconstruction of old bridges that do not meet the demands of modern transportation is not only costly but also time-bound. The aging of old bridges and the reduction of carrying capacity have caused the great concern of all countries