Finite Element And Reliability Analysis Of Reinforced Axial Compressive Concrete Column

With the development of urban construction, the scale of buildingreinforcement industry is growing fast. Section Increasing Method, as one ofrelatively simple-constructed and cost-effective methods, is used widely inreinforcement projects at the present stage. In the projects, repair of reinforcedconcrete columns occupies a large proportion. So this paper selected the reinforcedconcrete column strengthened by Section Increasing Method as the research object,and mainly discussed its mechanical behavior and security. Also shear properties ofthe interface are involved.Finite Element Method as a powerful numerical method has been widely usedin the building reinforcement industry. ABAQUS as powerful analysis software isused to investigate the properties of reinforced concrete columns under axialcompression in the paper and through it a lot of information of deformation, stressand cracks etc. are received. The result of ABAQUS analysis shows that lateraldeformation at the central part of the strengthened column would be too largewithout stirrups and as a result the excessive deformation leads to the decrease ofthe bearing capacity of the column, meanwhile it pointed out the crack width is thelargest at the midst along the length of the column and the stress difference betweenthe old and new concrete at the central part is relatively small compared with that atthe top and the bottom. Strength utilization of the longitudinal reinforcement in theold concrete is higher than that of new concrete because of the restraint of the newconcrete.Building security has received wide attention, especially reliabilityrequirements of structures are higher and higher, thus improving reliability index ofthe structure has become increasingly important. This paper used MATLABsoftware to calculate the reliability index of normal bearing capacity of thereinforcement concrete column under axial compression, compared the reliabilityindex of different load effect ratio, cross-sectional dimension, concrete strength,steel yield strength, reinforcement ratio and formulas approximate coefficient. It isfound that when the value of load effect ratio (ratio of the live load and dead load)varied from0.1to9.0, the reliability index increased firstly and then decreased, receiving the minimum and maximum value at0.1and1.0respectively; Fordifferent load effect ratios and different concrete levels of the new concrete, the sizeof the new concrete column section impacted the reliability as follows, thereliability would be higher if the areas of the new concrete and old concrete arecloser with each other; the reliability will be improved with the increase of theintensity level, the steel grade and reinforcement rate.Relevant literature showed that the interface of new and old concrete is a weakarea from the viewpoint of forces. For this reason the paper discussed the influenceof surface roughness and soundness as well as modulus mismatch between repairand substrate concrete to the compression/shear, pure shear, and tension/shear tests.At last a bond failure envelope that encompasses all possible normal/shear stressstates was put forward. Through the envelope a more comprehensive and moreintuitive picture of the comprehensive and intuitive interface bonding properties canbe obtained. The envelope can either be applied directly in the reinforcementprojects, or used to predict the bound performance of a variety of patched forms.