ECCENTRICALLY BRACED STEEL FRAMES FOR EARTHQUAKES

Abstract

A unique, practical structural steel system that possesses many advantages in the seismic design of structures is described. The system employs diagonal bracing with large eccentricity between the brace-beam connection and the beam column joint. The eccentricity provides a ductile fuse that yields in shear and prevents brace buckling. Static and dynamic analyses indicates that this system can perform well during earthquakes, because it combines the stiffness of a braced frame with the excellent energy dissipation of a moment-resisting frame. One-third-scale experiments showed that the system behaves as predicted in the analyses. It dissipates large amounts of energy while maintaining a very stiff structure, and it offers many potential applications in the seismic design of structures.