PARAMETRIC STUDIES ON THE MOMENT RESISTANT BEAMCOLUMN CONNECTION BEHAVIOR OF CONCRETE FILLED DOUBLE STEEL TUBULAR COLUMNS AND I STEEL BEAMS

The configuration of Concrete filled double steel tubular cross-section (CFDST) has the potential to overcome the beam-column connection difficulties found in steel tubular cross-sections. Since experimental parametric studies are expensive, numerical methods are adopted in this study to understand the behavior of beam-CFDST column connection under monotonic and cyclic loading conditions. The connection type is observed to be as semi-rigid as per EN1993-1-8. Parametric study includes design parameters like, concrete infill strength, yield strength of inner steel tube and outer steel tube, hollowness ratio, width to thickness ratio of inner steel tube and outer steel tube, end plate thickness and provision of stiffeners for end plate. Thickening the inner steel tube locally at the bolt location and providing stiffener plate or bracket at the compression zone of the extended end plate improves the rotational capacity of the connection as high as 0.06 rad for full plastic moment capacity of the beam. Recommendations are given for proportioning the connection components like end plates, bolts, inner steel tube and stiffeners for an optimal semi-rigid connection design.