Compression-bending behavior of irregular pentagonal CFT columns with different cavity structures: Experimental study

Abstract

This paper reported the test results of six irregular pentagonal concrete filled steel tube (CFT) columns with different cavity structures. The columns were tested under a constant axial compression and lateral low cyclic load. The test parameters are the lateral loading direction, cross-sectional cavity quantities, and with or without embedded reinforcements. The influence of these parameters on failure mode, strength, elastic-plastic deformability, energy dissipation ability was investigated. It was found that, irregular pentagonal CFT columns exhibit favorable ductility and energy dissipation ability. The multi-cavity structure significantly increases strength, while the reinforcements effectively improve ductility. Also, the bottom cross section strain distribution nephogram was mathematic fitted according to the measured gauge values. And it was founded that the bottom cross-sectional deformation obeys the plane cross section assumption before and at peak load point. And then, a calculation model using fiber model method was established considering difference among the cavity structures. The lateral load versus displacement curves, and axial load versus ultimate moment correlation curves are all predicted. Analysis shows that the constitutive relationship of confined concrete suggested by the author is better than available Han's in the prediction accuracy.