Durability Evaluation Of Concrete Arch Bridge Based On Non-probabilistic Reliability

Neutralization of concrete is a precondition for the corrosion of steel bars in reinforced concrete structures.The generally atmospheric environment and acid rain environment have adverse effects on the durability of concrete structures.Most of the reinforced concrete structures in actual engineering are under stress,and even worse,they are in cracked state,which has a serious impact on the durability of concrete.In order to fully grasp the health condition of bridge structures,it is necessary to evaluate the durability of bridge structures reasonably and effectively.This paper aims at the reliability evaluation of current concrete durability based on the theory of random probability,which requires a large numbers of statistical samples and is difficult to achieve the deficiencies.The introduction of non-probabilistic reliability methods,the using of theoretical analysis,experimental testing and engineering examples combined ideas to develop the work related to concrete durability evaluation,the main research contents and conclusions are as follows:(1)Carry out concrete carbonation tests under stress conditions and found that: the concrete carbonation is inhibited when compressive stress level in the interval [0~0.5];the tensile stress has a catalytic effect on the carbonization reaction;the higher tensile stress level is,the faster the carbonization rate will be;Based on the experiment,the influence coefficients of tension and compression stress on carbonization were fitted,and the existing non-load bearing concrete carbonation model was revised.(2)The acid rain erosion test of concrete was carried out and Tests showed that acid rain has little effect on the neutralization depth of concrete.The compressive strength of concrete is slowly increased after being affected by acid rain and then gradually reduced.The stronger the acidity is,the more obvious decline will be.At the same time,the coefficient of influence of acid rain on the compressive strength of concrete is given by fitting.(3)Thetests were conducted combining the carbonation of concrete and the acid rain erosion.The results showed that after long-carbonized concrete was subjected to acid rain test,the acidic environment contributed less to the neutralization depth;after acid rain erosion,the depth of carbonation no longer increased.The acid environment inhibits the carbonation of concrete.(4)The results of cracking concrete carbonization test show that the crack width or depth can lead to a significant increase in the carbonation depth of concrete where havecracks.Based on the data of cracked specimens,a carbonization depth model at cracks was fitted.(5)A non-probabilistic reliability evaluation model of concrete durability was established.The reliability index and reliability were used as reference and compared with the probabilistic reliability method.The results showed that the non-probabilistic reliability method is more simple to calculate and has lower requirements on the original data,and the calculation precision is good.(6)The arch bridge was selected,and based on the carbonation test data of the members of the arch ring,column,bridge deck and other components,the durability reliability of the components and the system were evaluated with non-probability.A sensitivity analysis of the protective layer thickness,ambient humidity,and temperature was performed.It was found that increasing the thickness of the protective layer can effectively extend the life of the structure.