Lateral Force Distributions in Multistory Braced-Moment Frames

Abstract

Braced frames traditionally have been analyzed and designed as trusses with all joints modeled as pins, such that only the braces provide lateral force resistance. However, frames with gusset plate connections create a rigid joint zone between frame beams and columns, effectively resulting in moment frame behavior, particularly at larger drift angles when the braces have yielded or buckled. Described herein is a rationale for multistory braced-moment frames that includes the frame’s moment resistance to lateral displacements when subjected to story-drift angles where the lateral resistance of the frame comprises both brace and moment frame action.