| With the development of social economy in China,the construction industry develops rapidly.After entering the new century,there are more and more concrete buildings,most of them are concrete structures,and a considerable number of buildings and structures have reached or exceeded the service life,or due to human and natural factors,they need to be strengthened by local components.There is also a special part of the building,because the current code design requirements and standards change,may not meet the current code design,need to re strengthen its structure.There are many reinforcement technologies and methods,such as increasing section,replacing concrete,sticking steel,wrapping fiber polymer and steel casing.This paper mainly studies the reinforcement of reinforced concrete column with circular steel jacket,which has outstanding mechanical properties,effectively improves the compressive strength of core concrete and makes the whole component extremely strong The limited bearing capacity changes in quality,which greatly improves the rigidity and ductility of the test piece,and the construction is fast and convenient,which has a high promotion value,and is widely used in bridge reinforcement engineering.In most cases,it is impossible to unload completely and then reinforce,but the initial stress of reinforced concrete members strengthened by steel sleeve is mostly ignored at home and abroad.Therefore,this paper makes a special study on this based on the team's preliminary test and the method of numerical analysis by finite element software ABAQUS.In order to study this kind of reinforcement,the following work has been done in this paper:(1)According to the previous experimental research of our team and the test of existing literature,the secondary stress model of reinforced concrete axial compression column strengthened by steel casing is established and verified in the test.The finite element calculation results are in good agreement with the test results.At the same time,the literature is searched to carry out the numerical simulation for the test conducted by the researcher using the modeling method in this paper to ensure the correctness of the numerical simulation.(2)Using the established finite element model to analyze the whole process of load-bearing of the reinforced column,and analyze the restraint effect of the reinforced concrete short column strengthened by steel jacket in the elastic stage,the elastic-plastic stage,the strengthening stage and the descending stability stage.(3)The influence of the thickness of the steel jacket,the strength of the grouting material and the strength of the steel casing on the ultimate bearing capacity of the composite structure with different initial axial compression ratio of the original column is compared by using the results of the finite element calculation.The influence of the initial stress level on the bearing capacity of the composite structure with the reinforced column is studied in depth,and the reinforcement effect of the steel jacket with primary and secondary stress is compared.(4)The preload formula of reinforced column is recommended,and the codes of China,Japan,Europe and the United States are listed.The test specimens collected in the existing literature are calculated,and the calculation results are compared with the code calculation results,and discusses the applicability of various formulas in calculating the short ultimate bearing capacity of steel jacke reinforcement. |
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