A framework is presented for assessing the sensitivity of typical engineering demand parameters (EDP) to the conditional period selection when using conditional mean spectra (CMS) as targets for ground-motion selection in a performance-based seismic evaluation. The framework consists of computing a suite of CMS targets anchored at conditioning periods within a period range of interest to discretize the demand at a given hazard level, as represented by a uniform hazard spectrum (UHS). Ground motions are selected and scaled for the CMS suite and the associated UHS. The envelope of the median responses from the CMS suite is compared with the median response from the UHS. The framework is instrumental in identifying the conditioning period ( T*) range for estimating CMS to capture the maximum median responses at the hazard level of interest. It also helps to characterize the relative difference in responses between using CMS targets and a UHS. The implementation of the methodology is illustrated by evaluating response quantities such as displacement-, acceleration, and force-based EDPs of four reinforced concrete moment frame structures of different heights under three levels of increasing hazard. Results confirm that the conditioning period used for ground-motion selection has a significant impact on the seismic response of displacement-based EDPs, and the sensitivity of the response varies with building height. For other EDPs, like maximum base shear and story acceleration, the results vary. Based on a limited-size ground motion set typically used in practice, the results indicate that UHS-targeted ground motions do not necessarily yield greater demand in comparison with using the CMS for estimating peak story drifts. For maximum floor accelerations, however, the CMS did produce smaller responses.

The response of mid-rise reinforced concrete (RC) buildings in Mexico City after the 2017 Puebla Earthquake is assessed through combined field and computational investigation. The Mw 7.1 earthquake damaged more than 500 buildings where most of them are classified as mid-rise RC frames with infill walls. A multinational team from Colombia, Mexico, and the United States was rapidly deployed within a week of the occurrence of the event to investigate the structural and nonstructural damage levels of over 60 RC buildings with 2–12 stories. The results of the study confirmed that older mid-rise structures with limited ductility capacity may have been shaken past their capacity. To elucidate the widespread damage in mid-rise RC framed structures, the post-earthquake reconnaissance effort is complemented with inelastic modeling and simulation of several representative RC framing systems with and without masonry infill walls. It was confirmed that the addition of non-isolated masonry infills significantly impacts the ductility capacity and increases the potential for a soft-story mechanism formation in RC frames originally analyzed and designed to be bare systems.

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