Experimental Study On Residual Bearing Capacity Of Damaged Concrete Tgirder

With the wide application of medium and small span concrete girder bridges,the evaluation of the residual bearing capacity of concrete bridges has been paid more and more attention by engineering sector.In this paper,concrete T-beam bridge as the research object,using the 20-meter-span concrete T-beam removed in the real bridge,using full-scale test,numerical analysis and theoretical calculation method to study the flexural capacity of concrete T-beam and T-Shear bearing performance.The main research works are as follows:(1)By full scale model test,the bending residual bearing performance of damaged concrete T beam bridge was explored;The load、deflection、strain and crack width of test beam were measured and analysised;The bending bearing performance of the full scale test beam was analysised;The bending failure mechanism of the damaged concrete T beam bridge was determined;The bending bearing performance of damaged concrete T beam bridge was put forward;The whole process of damaged full scale reinforced concrete T beam bending damage mechanics performance was clarified.(2)Through the full-scale model test,the shear-residual bearing capacity of the old concrete T-beam bridge is explored,and to analyze the load-deflection change,the strain of the stirrup,The stress of concrete,the strain of steel the strain of concrete roof and the development of diagonal crack.The shear bearing capacity of the full-scale test beam is analyzed,and the shear failure mechanism of the old concrete T-beam bridge is determined,especially in the limit state.And the shear behavior of the full-size concrete T-beam was obtained.(3)Considering the effect of damage on structural bearing performance,nonlinear analysis on flexural and shear performance of text girder was conducted by FEM software.Comparing the deflection and strain calculated curve which considers the damage reduction as well as calculated value of ultimate load and test value,finite element calculation results could basically indicate the mechanical mechanism of test girder in static loading process,and simulates the real stress state of test girder.After revising,the FEM calculated results on strain history of the reinforcements in top and bottom plate as well as stirrups agrees with the test results.(4)The theoretical analysis and calculation of concrete T-beam bending and shearing residual capacity are carried out in this chapter.Combining with failure mode of bending and shearing loading test,the theoretical calculation was discounted.The difference of result between calculation and full-scale test is about 5%.The simplified calculation formula considering damage can provide a reference for the residual capacity calculation.