Experimentally calibrated nonlinear hinge models for steel moment-resisting and concentrically braced frame systems

This paper presents regression-based backbone models for lumped-plasticity nonlinear hinges representing H-shaped beams, H-shaped braces, and HSS columns in steel moment-resisting and concentrically braced frames. The formulations are calibrated against 66 published cyclic tests and expressed in normalized form for direct implementation as user-defined hinges in commercial analysis software. Connection-specific beam hinges are developed for welded flange–bolted web (WFBW), reduced beam sections (RBSs) and cover-plated connections (CPCs) details, while brace and column hinges explicitly account for asymmetric inelastic behavior and axial load effects, respectively. Validation against experimental envelopes and existing code-oriented hinge models demonstrates improved prediction of strength and deformation capacities, particularly for modern high-strength steels. System-level application to a 15-story steel building is demonstrated through pushover analysis of the moment-resisting frame configuration and nonlinear response history analysis of the concentrically braced frame configuration. The results reveal that the proposed connection-specific hinges accurately predict a strong-column-weak-beam failure mechanism, whereas generalized code models overestimate beam ductility and misidentify failure modes. The dynamic analysis further illustrates the framework’s applicability to braced systems. These findings demonstrate that accurate component-level hinge modeling is essential for credible performance-based seismic assessment in ASCE 41-23 compliant evaluations.