The Analysis Of The Bearing Capacity Of Reinforced Concrete Bridges In Service Based On The Numerical Simulation

Bridges in our country is numerous, but with the passage of time and the rising ofmodern traffic, These Bridges appear in a variety of diseases. In our country, the majority ofhighway Bridges is reinforced concrete beam bridge, and is the most common diseases in thiskind of bridge.The reinforced concrete beam bridge will be a craze in the process oflong-term operation. With the development of crack, the structure of the stiffness will be fall,structural deflection will be largen under the same load, and the increase of deflection canmake the crack development more quickly, makes the decline of structure serviceability, andwill lead to structure in a certain period of use will become a dangerous bridge and facingdamage,the danger of collapse. Therefore, the reinforced concrete beam bridge in servicemust be proceed bearing capacity analysis.The briefly content of this thesis as follows:Based on crack this disease, summarizes types of concrete structure crack, analysis of allkinds of crack formation mechanism and its characteristics, and analyse the crosscracks.Establish the characteristic parameters of cracks through crack width, height and crackarea,calculate the effective stiffness of the cracking section acoording to the cross sectionanalysis method, and obtained the stiffness reduction coefficient. According to the crack area,reduction the stiffness of the different cracking characteristic parameters with crack section.Through the entity modeling of concrete hollow slab, several methods of reinforcedconcrete modeling is studied. the constitutive model of reinforcing steel, concrete constitutivemodel and failure criterion are discussed thoroughly. Studied in the model of reinforcedconcrete cracking simulation. Describes use solid65unit and link8unit in the simulation ofreinforced concrete structures.For concrete hollow slab with cracks do destructivetesting.Obtained the ultimate bearing capacity by analysis of test results. Through thenonlinear simulation of the entire process for concrete hollow slab, comparison of bearingcapacity with different items reduction. Get the effective method of stiffness reduction. Thedeflection and strain change with load get by finite element calculated contrast with the testresults.Demonstrates the simulation methods for the initial crack is accuracy andreasonableness in this thesis.Study on how to apply the initial prestressing when modeling in the prestressed hollowslab. Build a model with different crack width for nonlinear analysis of the entire process. Comparison load-deflection curves and ultimate bearing capacity at different crack width.Analysis results with increasing crack width, stiffness of the structure is reduced, thedeflection under the ultimate load increases, and the crack does not affect the ultimate bearingcapacity of the structure, Comparison of finite element calculations of different crack width,qualitative analysis of the impact of crack on the structure.Through the contents of the above research shows that simulating the effect of initialcracks on structure, the use of stiffness reduction method is feasible and effective, and theconstitutive relation of steel and concrete used in the limit load analysis is reasonable. Finiteelement results of different fracture parameters indicate crack will reduce the stiffness of thestructure, with the increase of crack width, the ultimate bearing capacity constant, thedeflection increases.