The Comparisons Between The Chinese And American Assessment Methods Of The Existing Bridges’ Carrying Capacity

In recent years, as the rapid development of economy and transportation infrastructure, more and more highway bridges was built. Meanwhile, due to the overloading of vehicles and bridge aging, the disease is produced on the bridge structure, and even causes of serious quality problems, Identify the bearing capacity of highway bridge should not be neglected, In China, Ministry of Communications has been developing a new bridges carrying capacity assessment method 《Specification for Inspection and Evaluation of Load-bearing capacity of Highway Bridge》, due to the development in bridge inspection technology. Previously at 1989. China’s Ministry of Communications issued 《Carrying-capacity of Highway Bridge Evaluation Methods (Trial)》 to assess the carrying capacity of highway bridges.1994,AASHTO issued 《Manual for Condition Evaluation of Bridges》 which put forward the LFD method. After then in 2011 issued ((Manual for Maintenance Inspection of Bridges)) put forward the LRFR method to assessment highway bridge of the United States.This paper elaborated the theoretical methods to assess the carrying capacity of the Sino-US highway bridges. The differences of the carrying capacity assessment methods of the Sino-US bridges were compared in assessment procedure, formula expression, parameter valuation, the classification of the bridge assessment and other aspects. At the same time, a research on testing, data collection and theoretical analysis of three domestic real bridges and pointed out the differences and similarities of the carrying capacity assessment results between the Sino-US bridges.The comparative study of Chinese trial method and JTG method showed that:the bridge carrying capacity assessment numerical results in JTG method is lower than the trial method. This shows that the new assessment procedure will help to ensure the safety of the bridges, but it will also increase the cost of maintenance.The comparative study of American LRFR and LFR methods indicated that:LRFR method gives lower bridge evaluation numerical results than LFR, ranged between 17% to 44%. American carrying capacity evaluation is consistent with the trend of China’s and it will also seek security more.The results of the numerical evaluation of the carrying capacity of the bridges is quite consistent calculated by JTG and LRFR, but comparatively speaking, the numerical result of the Chinese method for estimating the carrying capacity of the bridge is higher than the U.S. methods, and the U.S. methods have more strict assessment procedures.Finally, some problems of the evaluation theory and application is put forward and researching direction in further is analyzed.