A two-phase research program was undertaken numerically to assess the behavior of the beam outside of the link that is designed for overstrength of the link in eccentrically braced frames (EBFs). In the first phase, software was developed to conduct a statistical analysis of the typical cases designed according to the AISC Seismic Provisions for Structural Steel Buildings. In this analysis, it was noticed that most of the statistically analyzed cases do not satisfy the code requirement provided for overstrength factor. Furthermore, the analyses results revealed that troublesome designs are highly influenced by normalized link length and slenderness of the beam. In this phase, redistribution of forces between beam and brace after the yielding of beam was also studied and it was observed that the forces not carried by the yielded beam are taken by the brace. In second phase, a total of 91 problematic designs were analyzed on finite element program to investigate the effective parameters on the overstrength issue, and overall and local stability of the beam outside of the links. According to analysis results, it was observed that unbraced beam length and flange slenderness are responsible for the stability of the system. Based on these results, the boundary values were suggested to prevent lateral torsional buckling of the beam and local buckling of the brace connection panel separately. Moreover, the overstrength factor specified by code was found conservative for the intermediate and long links although it is fit for the short links.

Design recommendations for steel plate shear wall (SPSW) systems have recently been introduced into seismic provisions for steel buildings. Response modification, overstrength, and displacement amplification factors for SPSW systems presented in the design codes were based on professional experience and judgment. A numerical study has been undertaken to evaluate these factors for SPSW systems. Forty four unstiffened SPSWs possessing different geometrical characteristics were designed based on the recommendations given in the AISC Seismic Provisions. Bay width, number of stories, story mass, and steel plate thickness were considered as the prime variables that influence the response. Twenty records were selected to include the variability in ground motion characteristics. In order to provide a detailed analysis of the post-buckling response, three-dimensional finite element analyses were conducted for the 44 structures subjected to the selected suite of earthquake records. For each structure and earthquake record two analyses were conducted in which the first one includes geometrical nonlinearities and the other one includes both geometrical and material nonlinearities, resulting in a total of 1760 time history analysis. In this thesis, the details of the design and analysis methodology are given. Based on the analysis results response modification, overstrength and displacement amplification factors for SPSW systems are evaluated.