Full‐scale experimental assessment of new connection for columns in vertically mixed structures

Abstract

SummaryMore stiffness of concrete frames on one hand and fewer weight of steel frames on the other hand motivates using a composite system so called vertically mixed structures. The reinforced concrete and steel frames are connected together at a story called transition story. A major challenge for the designers is the connection columns in the transition story for proper transferring of efforts and preventing stress concentration phenomenon. There are some suggestions, in the literature, to build a transition composite column instead of constructing a local connection. Four full‐scale specimens of three connection types are constructed and tested experimentally under cyclic load to investigate hysteresis characteristics, failure mechanism, deformability, and energy dissipation capacity of the model. A novel through bolt lap connection adapted from concrete‐filled tube (CFT) column is proposed. Finally, backbone curves of proposed column for more accurate seismic studies are presented. No evident sign of local failure is observed in the proposed connection. Placing the steel around the reinforced concrete column section prepares the maximum possible geometrical dimensions for the steel column section and the connection. The experimental results show no strength loss for the new proposed connection under two different axial loads in lateral cyclic loading up to 4% drift.