Seismic retrofit and strengthening of buildings. Observations from the 2017 Puebla-Morelos earthquake in Mexico City

Review of Retrofit and Strengthening Strategies Used in Buildings in Mexico City After Strong Earthquakes

“…In a previous work, the authors discussed in detail, from several angles [1], the observed performance of previously 110 retrofitted and strengthened building which experience from light damage to partial collapses during the Puebla-Morelos earthquake. In this section, a briefer discussion will be done of aspects that the authors consider very relevant in the seismic retrofit of buildings in region of high seismic risk.…”

“…This is a small number, considering that in Mexico City there are more than 2,400 buildings retrofitted as a consequence of all previous strong earthquakes. It is worth noting that the identified damage categories are the following [1]: a) partial collapse (building with a story collapse, black category), b) demolished buildings (blue category), c) demolition list (buildings where demolition was recommended but it has not been done yet, purple category), d) high damage (buildings with severe structural and nonstructural damage, foundation problems and/or very large tilting, red category), e) medium damage (buildings with either some structural damage and/or important nonstructural damage and/or important tilting, yellow category), f) light damage (buildings with some light nonstructural damage or incipient tilting, green category).…”

“…Depending on the extent and severity of the earthquake damage, replacement of damaged materials, local strengthening and other integral rehabilitation strategies were performed in several of these damaged buildings for strengthening and retrofit projects, in order to extend their useful life [1]. Local repairing techniques and replacement of materials and complete structural elements have been commonly used in Mexico City since the late 1950s, as described and documented in greater detail elsewhere [1][2][3][4].…”

“…Depending on the extent and severity of the earthquake damage, replacement of damaged materials, local strengthening and other integral rehabilitation strategies were performed in several of these damaged buildings for strengthening and retrofit projects, in order to extend their useful life [1]. Local repairing techniques and replacement of materials and complete structural elements have been commonly used in Mexico City since the late 1950s, as described and documented in greater detail elsewhere [1][2][3][4]. However, in this paper the focus of attention is the observed performance of buildings which were retrofitted or strengthened since that time using different integral techniques, such as: a) column, beam and wall jacketing, b) addition of RC shear walls, c) addition of concentric steel bracing, d) post-tensioned exterior cable bracing, e) RC macro-frames, f) exterior exoskeletons, f) hysteretic energy dissipation devices, and, g) reduction of stories (removal of top floors).…”

Influence of axial compression ratio in building columns

“…The breach of actual seismic codes and standards by several existing buildings has been noticed and studied by some authors worldwide (Abou-Elfath et al, 2017;Domínguez et al, 2016;Falcone et al, 2019;López-Almansa et al, 2013;Miano et al, 2022;Quintana Gallo et al, 2022;Requena-Garcia-Cruz et al, 2022;Tena-Colunga et al, 2022), and accordingly, the collapse risk of these buildings against earthquake occurrence (Aboutaha et al, 1999;Alfarah et al, 2020;Pampanin & Akguzel, 2011;Ricci et al, 2011;Singh Rawat, 2017) has also been noticed. Furthermore, there are RC columns in Moment-Resisting Frame (MRF) buildings having such high ACR values that undergo excessive DCR, still for vertical loads, as reported by a recent study (Villar-Salinas et al, 2021).…”