Experimental study on the axial compression mechanical performance of thin-walled square steel tube-glued laminated timber composite hollow columns

To further enhance the compressive performance of glued laminated timber columns, thin-walled square steel tubes were bonded with glued laminated timber on the outer side to form thin-walled square steel tube-glued laminated timber composite hollow columns. Taking the hollowness ratio and slenderness ratio of the composite columns as research parameters, five groups totaling ten thin-walled square steel tube-glued laminated timber composite hollow columns were designed and fabricated. Axial compression tests were conducted on the composite columns, and relevant experimental data were obtained. The experimental study showed that during loading, the thin-walled square steel tubes and glued laminated timber could work together in bearing the load. When the composite columns were loaded to the later stage, local debonding of the epoxy resin adhesive occurred, leading to the failure of the composite action at the debonded areas. Ultimately, failure initiated with longitudinal splitting or crushing of the glued laminated timber, followed by local buckling of the steel tube, resulting in the loss of load-bearing capacity. Analysis of the test results revealed that the measured load-bearing capacity of the composite columns was significantly higher than the algebraic sum of the load-bearing capacities of the glued laminated timber and the thin-walled square steel tubes, indicating that this composite method can significantly enhance the load-bearing capacity. The study also showed that the extent of improvement in the load-bearing capacity of the composite columns is related to the hollowness ratio of the column cross-section and the slenderness ratio of the column: when the slenderness ratio of the composite column remains constant, the improvement in load-bearing capacity increases with the increase in the hollowness ratio, while as the slenderness ratio increases, the load-bearing capacity of the composite columns shows a decreasing trend. Based on these findings, a calculation formula for the load-bearing capacity of thin-walled square steel tube-glued laminated timber composite hollow columns was established, and an analysis of the initial compressive stiffness and ductility of the composite columns was conducted.