Research On The Bearing Capacity Evaluation Of Old Highway Concrete Bridge Based On Structural Calculations

With the role of the heavy traffic and the external environment, the carrying capacity and the technology state of highway concrete bridge will be declining which will affect the normal use. Therefore, how to assess the capacity of existing bridge in a scientific and rational way is an important task of the bridge workers. The "old bridge carrying capacity identification methods" (for trial) was promulgated by the ministry of Communications in 1988, which is the main basis for Old Highway Bridge carrying capacity evaluation However the used calculation formula in the identification is not an effective interface with the existing standard moreover the calculation coefficient values is a range, which has large subjective and arbitrary. So how to assess the capacity of old highway concrete bridge based on the structural calculations is studied in this paper. The main achievements and conclusions are summarized as follows:1. A modified capacity structural calculations formula of old highway bridges is proposed based on the existed research results of old highway concrete bridges evaluation methods and the current highway bridge capacity evaluation method design theory, which could be better cohesion with the existing highway bridge maintenance standard. The modified formula could be beneficial to evaluate the old concrete highway bridge bearing capacity using the inspection results.2. The technical state assessment method of the old highway concrete bridge based on series-parallel system was studied, while analyzed the carrying capacity assessment method of the component level, series system, parallel system and full bridge structure in detail.3. The main factors that affect the carrying capacity of old concrete highway bridges and the quantitative assessment criteria of each factor were studied. Moreover, by analyzing the degree of various factors affecting the structure bearing capacity and the mutual relevance of them, the weight coefficients that key factors (including durability aspects) that influence the bridge capacity is obtained by the AHP.4. Based on the division of series-parallel system of bridge structure ministries, the quantify calculation coefficients (including durability aspects) of the old bridge,the coefficients of the cross section reduction and live load influence coefficients were gained by fuzzy comprehensive evaluation. Using all these coefficients to amendment structural resistance and load effect at the same time, the results could be used to evaluate the old concrete highway bridge carrying capacity.This paper proposed a revised carrying capacity assessment method of old highway concrete bridges. This method could overcome the subjective defects of capacity structural calculation that based on the inspection results. One more scientific and rational bearing capacity evaluation of the old highway concrete bridges was provided.