Stress-strain relationship for confined concrete in various shapes of concrete-filled steel columns

摘要

A method to predict complete stress-strain curve of concrete subjected to triaxial compressive stresses caused by axial load plus lateral pressure due to confinement action in various sectional shapes of concrete filled steel tubes is presented. FEM analysis procedure with the help of a steel-concrete interaction model is adopted to estimate the lateral pressure in box and octagonal shaped columns. Subsequently, an extensive parametric study is carried out to propose a relationship for the maximum average lateral pressure. The lateral pressure so calculated is correlated to confined concrete strength through a well-known empirical formula. A fiber analysis procedure is followed to calibrate the post peak region of the proposed model. The columns adopted for the calibration are composed of different steel and concrete material properties and various sectional shapes. Finally, the predicted concrete strength and post peak behavior are compared with test results and found to exhibit good agreement.