A Component-Based Joint Model for Nonlinear Analysis of Bolted Extended End-Plate Connections

Abstract

Semi-rigid connections play a critical role in steel structures; however, most existing component-based approaches do not explicitly account for stiffness degradation and post-yield residual stiffness, which may reduce the accuracy of moment–rotation predictions. To address this limitation, direct numerical simulations (DNSs) of representative T-stub beam-to-column joints were conducted to investigate their nonlinear rotational behavior. Based on the observed joint response, a Joint Component Model (JCM) capable of representing sequential yielding, stiffness evolution, and residual rotational stiffness was developed. Constitutive relationships were derived, and a parameter identification procedure directly relating joint geometry and component mechanical properties to the model parameters was established. The proposed model was subsequently implemented in ANSYS and validated through analyses of T-stub joints and steel frames subjected to static and dynamic loading. The results showed good agreement between the JCM and DNS in terms of moment–rotation relationships, force–displacement responses, and dynamic time-history responses. Compared with DNS, the proposed model significantly reduced computational time while maintaining satisfactory prediction accuracy. The proposed JCM therefore provides an efficient and reliable component-based modeling framework for modeling semi-rigid steel connections and capturing stiffness evolution throughout the entire joint rotation process.