Graduation Semester and Year




Document Type


Degree Name

Doctor of Philosophy in Civil Engineering


Civil Engineering

First Advisor

Ali Abolmaali


The concept of hybrid steel frame system is presented in which mixtures of fully-rigid and semi-rigid steel connections are used in the 3-, 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 hybrid frames with the best seismic performance. The effective connection stiffness is identified by performing a parametric study on the initial stiffness of the semi-rigid connections. Then, the cyclic behavior of the connections with the most effective stiffness is obtained using nonlinear finite element analysis. Inelastic dynamic analyses are conducted on the proposed selected frames by subjecting them to Los Angeles earthquake records characterized as those with 2% and 10% probabilities of exceedance in fifty years. The maximum story drift for the hybrid frames are determined and compared with the "life safety" and "collapse prevention" performance limits as recommended by FEMA 356. The story drift and member forces for the hybrid frames are reported and compared with those of conventional SAC frames without semi-rigid connections. The nonlinear incremental modal analysis is also introduced as a tool for assessment of the behavior of frames under seismic loading. Finally, a reliability analysis utilizing the collapse margin ratio presented in FEMA P695 is performed to quantify and compare the collapse performance of the selected hybrid and rigid frames.The mid- and high-rise hybrid frames showed improved performance compared with rigid frames, especially under maximum credible earthquake (MCE) ground motions.


Civil and Environmental Engineering | Civil Engineering | Engineering


Degree granted by The University of Texas at Arlington