Joint strength in RCS frames

Abstract

As part of a National Science Foundation (NSF) program ics. on composite and hybrid systems at Texas A&M University, the objective of this thesis is to investigate the joint strength in reinforced column-steel beam (RCS) special moment frames with the addition of a compositely attached reinforced concrete (RC) slab. To carry out this objective, a series of 2/3 to near full-scale models for low-rise to mid-rise construction were designed according to published guidelines for RCS moment connections with the addition of a reinforced concrete slab. Specimens were tested in two orthogonal directions under quasi-static, reversed-cyclic loading. Joint strength predictions in the continuous beam direction of loading were made according to the ASCE guidelines (ASCE 1994), proposed strength models from Cornell the Architectural Institute of Japan (AIJ 1994). From nted in comparison of measured response to predicted response, recommendations were made for improving the ASCE strength models (1994) to account for the addition of a RC slab, cover plates, and band plates. Results indicated that the addition of a reinforced concrete slab compositely connected to the steel beams framing into a typical RCS joints as defined by the ASCE guidelines (1994), improved the joint panel shear strength by increasing the width of the inner concrete compression strut and/or the outer concrete compression field, depending on the joint configuration. In addition to the direct contribution to joint panel shear strength, cover plate details also seemed to increase the inner and outer concrete panel widths for joint panel shear strength. Band plates also appeared elective in increasing the elective joint width and/or maximum compressive stress in the concrete bearing zone conjoint vertical bearing strength. For the discontinuous direction of loading, proposed joint strength models were further modified. For vertical bearing strength, the moment arm for the bearing elements was reducers as the beams rotate independently about the centerline of the connecting bolts, instead of as a rigid body about the center of the joint. For joint panel shear strength in the discontinuous beam direction of loading, the contribution of the steel web was neglected.