On the concept of earthquake resistant hybrid steel frames

The concept of hybrid steel frame system is presented in which mixtures of fully-rigid and semi-rigid steel connections are used in the 9 and 20-story SAC frames. Several different patterns and locations of semi-rigid connection replacements within the frame are examined in order to identify the hybrid frames with most energy dissipation capabilities. Inelastic dynamic analyses are conducted on the proposed selected frames by subjecting them to the Los Angeles earthquake records characterized as those with 10% probabilities of exceedance in 50 years and 2% probabilities of exceedance in 50 years. The maximum story drift for the hybrid frames are determined and compared to the “life safety” and “collapse prevention” limits as recommended by the FEMA 356. The roof-displacement time history, story drift, and member forces for the hybrid frames are reported and compared with those of conventional SAC frames without semi-rigid connections.