Research On Disease And Load-Bearing Capacity Of Concrete Beam Bridge

As bridge structure can be seen the throat project to the road, therefore its safety has a crucial significance on the development of transportation and the national economy. Concrete beam bridge not only is the most common type of bridge structures on the road, but als.o has longer constructed time, larger quantities and wider geographical distribution. Due to the annual growth in traffic, environmental impact on bridge, and the aging of bridge itself, there are various types of bridge diseases existing. However, there are no accurate and effective quantitative methods to analyze the impact of diseases on the bearing capacity and normal use conditions of existing bridges.In this paper, the assessment of typical diseases and bearing capacity of highway bridges are taken as a starting point, finite element software Midas and empirical formulas through theoretical derivation are applied to expand research on existing reinforced concrete simple beam bridge. Main research contents are as follows:(1) Firstly, the paper gives a detailed research and classification on the diseases of concrete beam bridge, which makes foundation on the realization of the standardization of disease investigations, and provides a theoretical basis and foundation for quantifying the bearing capacity.(2) Based on the concrete carbonation and steel corrosion degradation model, and considering the relationship between the carbonation depth and time, this paper uses Matlab programming draw a figure related with the relationship between carbonation depth and material strength, steel sectional area. In addition, the concrete compressive strength, elastic modulus, steel corrosion rate, yield strength and the change of bonding capacity between concrete and steel are calculated, under different carbonation depth, which laid the foundation for the establishment of the finite element analysis model.(3) Through the analysis of concrete carbonation and steel corrosion degradation model, the finite element model of damaged reinforced concrete simple beam bridge is developed by reducing steel sectional area and material strength. The deformation values under the load cases of different damaged models are obtained. In the end, the paper fits the relational expression about the structural deflection and load carrying capacity, in which carbonation depth is taken as the dependent variable.(4) Based on the measured statistical parameters of bridge flexural cracks, the section numerical analysis and the iterative method, the damaged finite element model is derived by the calculating reduction of stiffness. Furthermore, this paper analyzes the impact of different crack width and different crack positions on the maximum deflection values.