Estimation Equation for Horizontal Load Bearing Capacity of Circular PCFST with Diaphragm

The purpose of this study is to propose a practical formula for estimating the maximum load bearing capacity of partially concrete-filled steel tubes (PCFST) without using complicated numerical analysis and estimation procedures. This study focused on four parameters (radius thickness ratio R, slenderness ratio lambda, axial force ratio n, and concrete filling ratio Lc/L) used in numerical analysis to determine horizontal load bearing capacity and buckling position in PCFST with diaphragms under monotonic loading. Based on the results, an equation for estimating the horizontal load bearing capacity of PCFST was obtained by nonlinear regression analysis. The estimation equation that did not consider different buckling positions predicted the horizontal load bearing capacity with an error of approximately +/- 10% from the numerically analyzed values, but the estimation equation that took the different buckling positions into consideration could predict the horizontal bearing capacity to within a margin of error of about 5% from the numerical value by determining the buckling position in advance.