This study quantifies the impact of two common ground motion (GM) selection methods, included in U.S. standards, on the seismic performance evaluation of steel special moment frames. The methods investigated are a “traditional” approach, herein referred to as the target maximum considered earthquake (TMCE) method, and a newer approach known as the conditional mean spectrum (CMS) method. The TMCE method selects GMs using the risk-based maximum considered earthquake (MCER) spectrum as the target spectrum, while the CMS method uses the CMS that anchors the MCER at multiple conditioning periods. Three special steel moment frames of 4, 8, and 16 stories are designed in accordance with ASCE/SEI 7-10, and their seismic performance is assessed with the nonlinear dynamic procedure prescribed in ASCE/SEI 41-13 using GMs selected and scaled in accordance with the aforementioned methods. A comparison of statistical parameters for the reduced beam sections and column hinges is conducted using the normalized demand-to-capacity ratio ( DCR), as the output parameter. The buildings are evaluated at the collapse prevention performance level for a far-field site located in Los Angeles, CA. In general, the CMS method results in lower DCRs of the frame components and smaller output parameter dispersion. In addition to the spectral shape, the demands are largely influenced by the spectral accelerations prescribed for each evaluated method. The consideration of collapse realizations is also documented as well as the existing and proposed statistical methods to account for these realizations. The study shows that the GM selection process can cause significant differences in structural response that may lead to different retrofitting decisions.

This study quantifies the impact of different ground motion selection methods on the seismic performance evaluation of steel special moment frames. Two methods are investigated: a "traditional" approach, herein referred to as the Pacific Earthquake Engineering Research (PEER) method, and a newer approach known as the Conditional Mean Spectrum (CMS) method. The PEER method selects ground motions using the Riskbased Maximum Considered Earthquake (MCER) as the target spectrum, while the CMS method uses the conditional mean spectrum that anchor to the MCER at multiple conditioning periods. Three special moment frames of 4-, 8-, and 16-stories are designed in accordance with ASCE/SEI 7-10 to represent archetype steel frame buildings as found in regions of high seismicity. The seismic performance of these frames is assessed with the nonlinear dynamic procedure prescribed in ASCE/SEI 41-13, using ground motions selected and scaled in accordance with both methods. The performance of the buildings is evaluated at the Collapse Prevention (CP) performance level for a far-field site located in Los Angeles, CA. The CMS method results in lower mean and median response in terms of demand-to-capacity ratios in the reduced beam sections and column hinges. Ground motions selected and scaled using CMS result in a smaller dispersion of the output parameters in most of the beam and column elements, if the conditioning period that results in the highest mean demand-to-capacity ratio is the fundamental period, 1. The results of this study show that the ground motion selection process can cause significant differences in structural response that may lead to different retrofitting decisions. These results provide

No abstract