Analytical modeling of composite steel-concrete frame systems

Abstract

Equivalent macromodel based analytical tools, comprised of flexibility-based element models, are used to accurately represent the non-linear moment-curvature (force-deformation) response characteristics in structural systems using colunms of reinforced concrete or composite steel shapes encased in reinforced concrete (SRC), structural steel beams, and composite beam-column joints. To facilitate the modeling of inelastic deformations in joint regions, a panel element capable of representing joint shear distortions and joint bearing deformations was incorporated into an existing computer program, IDARC (Kunnath and Reinhorn 1994). The inelastic shear deformation characteristics of the joint panel were partly established from guidelines published by an ASCE Task Committee (ASCE 1993). Various hysteretic control parameters for members of the subassemblage, such as strength degradation, stiffness deterioration, and pinching (slip), were quantified based on observed experimental response (Kanno 1993). Potential failure modes of the frame subassemblage in the steel beam, reinforced concrete or SRC column, and composite joint were able to be represented in the proposed formulation. Experimental subassemblage testing performed at Cornell University (Kanno 1993) was used to validate the analytical platform. It is shown that the revised IDARC program can be used for seismic evaluation of composite structures and in the development of design guidelines to ensure desirable mechanisms in composite frame structures.