Analytical Investigation on Seismic Behavior of Inverted V-braced Frames

Abstract

An inverted V-braced frame is one of the most widely used CBFs (Concentrically Braced Frames) owing to many advantages in constructional design. The seismic behaviors of inverted V-braced frames is that brace buckling occurs due to strong motion generation, and that in turn vertical unbalanced force is created between tension brace and compression brace, resulting in an additional load onto beams. Thus, members of beams should be designed to have enough strength to ensure plastic hinge is not created. In this study, a series of finite element analysis was conducted to evaluate the earthquake-resistant performances of the methods to design the clearance distance of gusset plates in inverted V-braced frames, and to evaluate vertical unbalanced force depending on the cross-section size of beams. It was found that the results of the equation of vertical unbalanced force in the current standards were more conservative than the load generated through the real analysis model. In addition, the model of designing elliptical clearance distance showed higher earthquake-resistant performances than that of designing linear clearance distance, which requires the reconsideration and improvement of the current practices of calculating vertical unbalanced force and setting clearance distance.