Panel Zone Shear Behavior of Through-Flange Connections for Steel Beams to Circular Concrete-Filled Steel Tubular Columns

Abstract

This research investigated the panel zone shear behavior of a proposed through-flange connection for steel beams to circular concrete-filled steel tubular (CFT) columns. Four exterior beam-column specimens were designed and tested using cyclic loading applied to the beam end. Three design variables were examined: concrete infill in the column tube, stiffeners to the column tube in the panel zone, and the width of the through-flange plates. Test results showed significant panel zone shear yielding for all specimens. Failure of the specimens was caused by fracture of the column tube near the through-flange plates and crushing of concrete at the stiffener side in the panel zone if concrete infill was present. The use of concrete infill, stiffeners, and 25% wider through-flange plates increased the peak applied load by 156, 7, and 14%, respectively. A model that considers crushing of concrete at the stiffener side as failure mode was proposed to calculate the panel zone shear strength contribution from concrete. If confined concrete strength was used, the panel zone shear strengths calculated with concrete contribution based on the proposed model were, on average, 8% more conservative than the test results. If unconfined concrete strength was used, the calculated panel zone shear strengths were, on average, 63% more conservative than the test results. The panel zone shear strengths calculated with concrete contribution based on the ACI 318 and ACI 352 R methods were, on average, 46 and 39% more conservative than the test results, respectively.