Elastoplastic Behavior of Panel Zone in Steel Beam-to-Concrete Filled Steel Tube Column Moment Connections

Subassemblage tests were conducted on the panel zone within steel beam-to-concrete filled steel tube (CFT) column moment connections made from high-strength material to investigate their elastoplastic behavior. The writers propose a nonlinear shear force-deformation model for the panel zone in beam-to-column CFT connections for predicting the elastoplastic behavior of the panel zones. The proposed model includes a superposed model based on a trilinear shear-deformation relationship for the steel tube superposed on one for the concrete core, and a simple model provided as a trilinear model having a yield strength point and an ultimate strength point for this panel zone, as a practical model for design. The writers also propose a method for evaluating load resistance, in which a new theoretical compression strut mechanism is utilized, taking into account the confinement of the tube flange. The results predicted using the superposed and the simple model are found to agree approximately with the experimental results up to a large shear deformation of 0.04 rad.