Joints behaviour of through steel beam to composite column connection: Experimental study

The objective of this study is to categorize the failure modes; moment and rotation capacities; ductility; stiffness; joint classification; strain behaviour; and load transfer mechanism of steel beam through CFST column connections. Eight one-third scale composite joints were tested under static load up to failure. The key parameters comprise two ηStrength ratios; the effect of beam flange and web continuity inside the connection zone; and full cross-section continuity of steel beam. Moreover, the contribution of the connection component to the overall capacity of composite joints was determined. Results indicated that through beam connection could provide an ideal rigid joint. The absence of beam flange and the discontinuity of full beam cross-section made the connection component highly susceptible to fracture. In contrast, the presence of these details leads to higher ductile behaviour and prevent joint failure. The flange contribution to the moment and rotation capacities is significant, contrarily to the web contribution, which is negligible in value. The flange contribution to ductility coefficient is more dominated compared to web contribution. When strong column-weak beam criteria are followed, the continuity contribution to initial stiffness is more dominated. In contrast, the specimens that follow the weak column-strong beam criterion, the flange contribution to the initial stiffness has the major effect. •The concrete filled steel tube columns with classical and double skin cross-sections can be used in marine structures.•The most popular composite frames are usually composed of CFST columns and steel beams.•The behaviour of composite frame depends on the strength, stiffness, and ductility of the connection.•Rigid connections are highly preferred in the most of engineering structures for safeguarding the structure stability.•In marine structures, the structure stability is a challenging field due to the extreme conditions of the environment.