Conceptual design and axial-flexural performance of composite dowels columns

Steel-concrete composite columns have several engineering application scenarios in structural engineering. However, existing composite columns face several challenges including interfacial concrete debonding, inflexible cross-sectional configurations limit adaptability. To resolve these issues, this paper proposes a novel Composite Dowels Column (CDC) utilizing puzzle-shaped composite dowels. The connection performance of the composite dowels ensures robust steel-concrete bonding, eliminating debonding risks. Flexible cross-sectional adjustment is achieved by modulating concrete casting thickness, enabling precise control of strong-axis and weak-axis moments of inertia. Building on this design concept, the study systematically investigated the influence of seven factors affecting the axial-flexural capacity of CDC, i.e., the capacity under both axial forces and bending moments, which includes material strength, eccentricity, transverse links, flange width-to-thickness ratio, section aspect ratio, and embedment depth of PZ composite dowels. Among these factors, concrete strength and flange width-thickness ratio are found to be the two governing factors of CDC. The CDC exhibits superior axial-flexural capacity compared to Partially Encased Composite columns with the same steel consumption, which is benefited from its adaptable cross-section. The failure mode of composite dowels columns under eccentric compression is identified, and a design method for axial-flexural capacity is established. This work provides guidance for the future engineering application of this novel column system.