FE analysis of ultimate strength of circular CFT columns considering creep effect

Abstract

This paper introduces a simple but effective strength reduction factor to directly determine the strength reduction due to the creep deformation of concrete in circular CFT columns. Upon constructing the linearized P-M interaction diagram on the basis of the design procedure introduced in the previous paper or described in the existing design codes, multiplying the introduced strength reduction factor makes it possible to determine the ultimate resisting capacity of CFT columns without a rigorous time-dependent nonlinear analysis. The efficiency and accuracy of the introduced strength reduction factor are verified through comparison of the P-M interaction diagrams determined by the use of the strength reduction factor and those obtained by rigorous nonlinear analysis considering the creep deformation. Numerous additional parametric studies show that the introduced strength reduction factor can effectively be used especially in the preliminary design stage where many trial and error procedures are performed while considering the creep effect in concrete to select a proper section dimension of a CFT column.