Study On The Diseases And Bearing Capacity Of Highway Damaged Bridge Beams

The highway communication is the lifeblood of the national economy, and the bridge is a throat of the highway, so the good use status of the bridge is the important decisive factor of the traffic safety and the requirement of ensuring unblocked of the highway. As the flow of highway communication increases, bridges are bearing heavier and heavier load. Disease, damage, bearing capacity reduction of the highway bridge and the drops of serviceability are serious problems day by day. It is a general phenomenon that diseases exist in the bridges and components of the bridges are damaged. In all kinds of bridge types, Beam Bridge takes the majority. The disease of superstructure of reinforced concrete beam takes the leading factor to the decline of structural serviceability. As to superstructures of Beam Bridge which have congenital quality defect or damage, how to consider various damage impact on bearing capacity of component, how to analyze and calculate bearing capacity and degree of safety, there are no unified standard and method yet at present. Can only follow the damage degree and personal experience to reduce and estimate roughly at present, so the precision of calculation is quite bad.In order to assess the impact of the diseases on the serviceability and bearing capacity of beam bridges accurately and to guide the design of strengthening and maintenance management of bridges, the diseases of damaged concrete beams in the highway are analyzed and the bearing capacity after damaging is researched based on the scientific research project "the concrete beam damages and bearing capacity research" (subject serial number Y-030201) of the traffic office of Hebei. First step, combining the technological investigate of the bridge, the damage situation of reinforced concrete beams and their influence are analyzed and researched thoroughly. The typical disease characteristic of super structure of beam bridges of the highway is sum up. Then the cause of the typical disease, mechanism of function, the impact on serviceability such as the bearing capacity and durability and the influence among various diseases are analyzed and discussed thoroughly.As to the analysis of bearing capacity after damaging, non-destructive ideal state concrete beam that is analyzed in the whole course by strength is in the majority and there is less consideration of the disease factor in the former literature. Even some research is carried on in literature, but it only involves the analysis of a few kinds of disease influence. Because of the complexity of the bridge performance of the highway and the variety of the working environment, often on a bridge, even on a slice of beam, there are many kinds of typical diseases at the same time. The disease can cause comparatively serious influence on the bearing capacity. Based on the actual conditions, various common typical diseases of reinforced concrete beam are considered and the overall damaged reinforced concrete beam finite element models are set up. The suitable finite element model for analyzing reinforced concrete beam bearing capacity, the finite element unit and finite element simulation method about reinforcing bar, concrete, bonding strength, crack and various typical disease damage are chose, which can analyze the impact on disease of reinforced concrete beam of most highway bridges and realize micro and whole course analysis of the stress.In the course of the study, the following innovative work is carried on:First, the disease classification of damaged concrete according to the stress characteristic is proposed and the standard receiving the analytical method of strength is put forward. The finite element model of the structure according to all kinds of damage is differentiated.Second, according to disease investigation and mechanics analysis, the bearing capacity appraisal method and relevant indexes of highway reinforced concrete beam after damaged—damage bearing capacity and bearing capacity damage coefficient are proposed.Third, the corrosion disease intensity of concrete is graded and the finite element simulation method of the corrosion disease at all levels and the finite element simple analysis method and easy algorithm of corrode swelling pressure load effect are put forward.Fourth, the corrosion disease development degree of reinforcing bar is graded and the finite element simulation method of the corrosion disease at all levels is proposed.