The Finite Element Analysis Of Mechanical Performance Of Strengthened Concrete Columns With Bonding Under Compression

Large finite element software—ABAQUS is applied to analyze strengthening results of concrete columns with different bonding and strengthening approaches. In the finite element model, concrete damaged plasticity model is used for inner concrete while three-folding-line elastic-plastic model is taken for outer wrapping steel. And as for the fiber and interface between concrete and steel plate, orthotropic elastic model and jointed model are considered respectively.Main research works are listed as followings:(1) Model selection and verification. According to the mechanical characteristics of concrete columns, appropriate constitutive relations are adopted to build the finite element model. Concerned wrapping-steel strengthening test and wrapping-fiber strengthening test are used to compare with results from finite element model computation. It can be concluded that they agree well with each other and finite element model computation may supplement concerning tests in some ways.(2) Mechanical analysis of wrapping-steel columns. Under the conditions of axial compression, the influence of concrete strength, steel plate thickness (steel ratio), steel yield strength, batten spacing on the ultimate bearing resistance and ductility of half-wrapped columns are analyzed in the finite element model, secondary loading as well as eccentric loads conditions are also considered. The influence of steel ratio in axial condition and eccentricity in eccentric condition are also computed for full-wrapped columns. The computation results indicate that wrapping-steel technique can remarkably improve the ultimate bearing resistance and ductility of strengthened columns, the factor of secondary loading has little effect on the strengthened columns, full-wrapped columns are superior in eccentric loading to half-wrapped columns.(3) Mechanical analysis of wrapping-fiber columns. The influence of fiber thickness as well as elastic module on the ultimate bearing resistance and ductility of wrapped columns are computerized under axial loads. Meanwhile, confined effects of different section are compared with each other. The computation results indicate that wrapping-fiber strengthened columns can improve the property of ultimate bearing resistance and ductility to some extent, circular section columns have more efficiency than square section columns when confined by fiber material.