Experimental investigation on square steel tubular columns with initial crack defects

Abstract

The influence of initial cracks on the buckling performance of square steel tubular (SST) columns, widely used in civil engineering, is an aspect that has not been studied in detail. Thus, an experimental investigation was conducted on SST columns with initial crack defects. A total of 111 specimens (12 single-crack, 48 double-crack, 48 three-crack, and 3 no-crack SST columns) were tested under axial compression loading, and the failure modes, initial stiffness, bearing capacity, ultimate displacement, and strain strength of each specimen were reported. Combined with the experimental data, a finite element analysis of the validated model was conducted to evaluate the effect of the main influencing factors. A reduction coefficient was obtained via statistical analysis and introduced into the prediction formula to accurately estimate the ultimate bearing capacity of multicracked steel tubes. It was found that avoiding crack propagation in practical engineering is crucial. The initial cracks accelerated the local buckling and changed the bearing and deformation capacities of the SST columns. The ultimate loads of the steel tubes increased gradually with an increase in the tube thickness and decreased slightly with an increase in the crack length. Furthermore, the effect of crack number and crack spacing on the bearing capacity was found to be complex, and there was a coupling relationship with the tube thickness; therefore, the tube thickness of the component should be reasonably selected, or appropriate anti-cracking measures should be employed to avoid the joint action of material uneven stress and initial crack.