ANALYSIS OF MEDIUM RISE BUILDINGS AT MEXICO CITY WITH A SOFT AND WEAK FIRST STORY CONFIGANALYSIS OF MEDIUM RISE BUILDINGS AT MEXICO CITY WITH A SOFT AND WEAK FIRST STORY CONFIGURATIONANALYSIS OF MEDIUM RISE BUILDINGS AT MEXICO CITY WITH A SOFT AND URATION

Abstract

When a structure has a great contrast of stiffness and strength between two consecutive stories, a soft and weak story mechanism can be generated, as it has a great vulnerability in those stories. If in addition the structure is founded in soft soils, its vulnerability may seriously increase. During the earthquake in September 19, 2017 earthquake which hit Mexico City strongly, many buildings with a soft and weak story configurations resulted experienced severe local and global structural damage. Most of the seriously affected structures were found at soft soils. In this study, the analyses of two buildings which developed severe structural damage due to a soft and weak story configuration are presented. In addition, an alternate design proposal is presented, where a better contrast of stiffness and strength was used, and may have kept both structures safe during this strong earthquake. These proposals take as starting point current design guidelines of Mexico City, in particular the most recent buildings codes (2004 and 2017).