ABSTRACT
An experimental and analytical study was conducted to evaluate the effects of lateral bracing and system restraint on the behavior of reduced beam section (RBS) moment connections in a moment frame. Two full-scale RBS moment connections, one with, lateral bracing near the reduced beam region and one without, were cyclically tested to evaluate the lateral bracing effects. Both connections were able to deliver a plastic rotation of over 0.03 radian without welded joint fracture. Although adding lateral bracing near the RBS region did not significantly improve the cyclic response of the RBS connection, it did reduce the strength degradation rate and buckling amplitudes for a story drift ratio beyond 3%. To investigate the system axial restraining effects, non-linear finite element analysis of a one-and-a-half-bay beam-column subassembly representing a portion of a multistory frame was performed. The system axial restraint significantly improved the moment connection behavior by reducing the web local buckling amplitude. Minor strength degradation was observed for the axially restrained connections.
