Capacity design assessment of composite reduced web section (RWS) connections

Abstract

A gap in current design approaches demands explicitly introducing a capacity design approach when designing steel-concrete composite reduced web section (RWS) connections. This paper addresses this gap by presenting test-validated finite element models and parametric investigations, focusing on the presence and absence of composite action over the web opening, the diameter, and the end-distance of the web opening. Additionally, the first-ever comprehensive experimental and numerical database from the literature on bare steel and composite RWS connections is compiled and thoroughly analysed to develop the capacity design assessment for such connections. Both parametric investigations and the database highlight the significance of the capacity design ratio between the connected components in achieving a desirable ductile mechanism. This is crucial, as evidenced by the results: a 15 % increase in the connection's moment capacity led to an average 21 % difference in dissipated energy, favouring the web opening with a diameter of 50do over 80do, in RWS connections with the presence of composite action. The results show that proper consideration of the capacity design approach in designing RWS connections ensures a stable yield mechanism is developed, resulting in the redistribution of global action and capping deformation demands on non-ductile elements. This enhances connections' rotational capacity and ductility by forming the Vierendeel mechanism. Lastly, the paper presents a detailing recommendation for employing RWS connections in both existing and new structures for seismic purposes.