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The Mexico Earthquake of September 19, 1985 - Statistics of Damage and of Retrofitting Techniques in Reinforced Concrete Buildings Affected by the 1985 Earthquake
Abstract
The 1985 Mexico City earthquake caused very serious damage, especially in reinforced concrete buildings, making it necessary to repair and strengthen many structures. The authors had the opportunity to study 114 of these retrofitted buildings. The data base created with the collected information contains the description of the building, its damages and the retrofitting techniques used. The statistical analysis of this information makes it possible to identify the correlation among the structural and foundation types, the dominant failure modes, the causes of damage and the repair and strengthening techniques used in this group of buildings.
... 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). ...
... Element strengthening techniques such as RC jackets [1][2][3][4][9][10][11] or latticed steel jackets [1][2][3][4][12][13][14][15][16][17][18][19][20] have been used extensively in Mexico City to strengthen buildings since the late 1950s. They have been applied in RC beams and columns to: a) repair individual damaged members [1][2][3][4]11], b) as an integral, strengthening strategy to increase both the global lateral strength and ductility of the subject structure [1][2][3][4][9][10], and c) as a part of an integral retrofit strategy when modifying substantially the dynamic characteristics and balances of internal forces when used together with removal of top floors [13], additional RC shear walls [1][2]4], additional steel braces [1-2, 4, 11-13, 14-17, 19-20] or hysteretic energy dissipation devices [18][19]. ...
... Element strengthening techniques such as RC jackets [1][2][3][4][9][10][11] or latticed steel jackets [1][2][3][4][12][13][14][15][16][17][18][19][20] have been used extensively in Mexico City to strengthen buildings since the late 1950s. They have been applied in RC beams and columns to: a) repair individual damaged members [1][2][3][4]11], b) as an integral, strengthening strategy to increase both the global lateral strength and ductility of the subject structure [1][2][3][4][9][10], and c) as a part of an integral retrofit strategy when modifying substantially the dynamic characteristics and balances of internal forces when used together with removal of top floors [13], additional RC shear walls [1][2]4], additional steel braces [1-2, 4, 11-13, 14-17, 19-20] or hysteretic energy dissipation devices [18][19]. ...
Mexico City is often subjected to the action of strong earthquakes and then, thousands of severely damaged buildings in Mexico City have been repaired or retrofitted since the 1957 earthquake. Different integral techniques have been used, 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). These retrofitted and strengthened buildings were again significantly tested during the Mw = 7.1 September 19, Puebla-Morelos continental normal faulting earthquake. In this paper, the observed seismic performance of the described strengthening and retrofit techniques of a representative inventory of buildings during the September 19, 2017 earthquake are reviewed. Both very good (most) and bad (fewer) performances are highlighted and discussed. It was observed and confirmed that, in general, most strengthened and retrofitted buildings performed well when the strengthening/retrofit strategy was integral, well executed, good maintained and the building was reasonably taken out of resonant responses or separated from their neighbors to reduce the potential of structural pounding. In addition, the dominant retrofit and strengthening techniques that are being used nowadays in Mexico City to rehabilitate buildings damaged as a consequence of the September 19, 2017 earthquake are also shown and discussed.
Keywords: Retrofit, strengthening, jacketing, steel bracing, exoskeletons
... Local repairing techniques such as epoxy resin injections in tiny cracks or expansive grout in thicker cracks of reinforced concrete (RC) and masonry elements have been widely used [1][2][3][4][5][6][7][8]. Replacement of buckled steel bars, broken stirrups, crushed concrete or masonry bricks have also been employed [2,[4][5][6][7][8]. ...
... Local repairing techniques such as epoxy resin injections in tiny cracks or expansive grout in thicker cracks of reinforced concrete (RC) and masonry elements have been widely used [1][2][3][4][5][6][7][8]. Replacement of buckled steel bars, broken stirrups, crushed concrete or masonry bricks have also been employed [2,[4][5][6][7][8]. Replacement of complete damaged elements such as RC columns, RC beams, masonry infill walls and concrete walls was also common [4,8,9]. ...
... Replacement of buckled steel bars, broken stirrups, crushed concrete or masonry bricks have also been employed [2,[4][5][6][7][8]. Replacement of complete damaged elements such as RC columns, RC beams, masonry infill walls and concrete walls was also common [4,8,9]. ...
Mexico City is frequently affected by the action of strong earthquakes which are primarily triggered from two seismic sources: a) subduction earthquakes along the Mexican Pacific Coast and, b) continental normal faulting earthquakes. As a consequence of strong earthquakes which have occurred since 1957, there are several hundreds of buildings in Mexico City which have been repaired or retrofitted after those strong earthquakes. Then, there is a valuable experience in the city on different seismic strengthening and retrofitting techniques for different structural systems. Rehabilitated buildings were again significantly tested during the Mw = 7.1 September 19, 2017 Puebla-Morelos continental normal faulting earthquake. In this paper, the authors focus their attention to the observed seismic performance of the most commonly used strengthening and retrofitting techniques within the city. From a detailed inventory of 1834 buildings compiled by the authors which experienced from light damage to collapse, 110 rehabilitated buildings experienced damage, but only 45 of them experienced severe structural damage or have been already demolished. It is worth noting that in only 18 rehabilitated buildings, the selected rehabilitation strategy was an important part of the observed severe damage. Unsatisfactory performances are discussed from different angles within the paper, highlighting the reasons for such bad performances. In many instances bad performances were related to poor detailing, possessed structural irregularities, resonant responses, erroneous conceptualization for the strengthening/retrofitting scheme, partial retrofits, or lack of adequate maintenance. It was found that water penetration to foundation boxes or mats in soft soils favored progressive tilting. Very satisfactory performances are also highlighted. Iconic retrofitted buildings and building complexes are also discussed. It can be concluded that most strengthened and retrofitted buildings performed well in general, particularly when the strengthening/retrofitting strategy was integral, well executed, good maintained and the building was reasonably taken out of resonant responses or separated from their neighbors to reduce the potential of structural pounding.
Keywords: Rehabilitation, Retrofit, Strengthening, Structural Irregularity, RC jackets, Latticed Steel Jackets, Wall Jackets, column jackets, beam jackets, wall jackets, steel bracing, exoskeletons, post-tensioned cable bracing, RC macroframes, steel macroframes, floor reduction, floor increase, hysteretic energy dissipation devices, ADAS devices, steel butresses, added frames, foundation interventions, foundation straightening, foundation strengthening, control piles, low redundancy, tilting, soil-settlements, structural pounding, deterioration, ductility demands, ductility spectra, structural irregularity, soft stories, weak stories, corner building, torsion, slender building, long plans, setbacks, reentrant corners, distinctive plans, floor openings, building codes, reinforced concrete structures, steel structures, masonry structures.
... One of the most important natural disasters facing human society today is the earthquake disaster, which is characterized by suddenness and destructiveness. In recent years, protecting against the destructive effects of earthquakes has received more attention, particularly concerning the collisions between adjacent structures, especially during previous earthquakes such as those in San Fernando 1971 [1], Mexico City 1985 [2], Lom Prieta 1989 [3], and Bhuj 2001 [4]. Pounding was also observed in recent earthquakes, such as Christchurch (New Zealand, 2011) [5] and Gorkha (Nepal, 2015) [6]. ...
... The horizontal and rotational stiffness and damping coefficients have been calculated using the formulas given by Eqs. (1) and (2). The corrected constants of swaying and rocking springs have been taken as β x = 1, β ϕ = 0.5. ...
Pounding between buildings that are not sufficiently separated has been observed several times during earthquakes. This destructive impact may severely damage the structure and lead to its collapse. Although it is impossible to completely eliminate such losses, measures can be taken to minimize them. This article investigates the effect of the variability of structural parameters, soil parameters, and seismic action on the seismic response of two colliding buildings, taking the soil-structure interaction (SSI) into account. Two adjacent structures closely separated, modeled as inelastic lumped mass systems with different structural characteristics, were considered in this study. Both structures were modeled in the analysis using multi-degree-of-freedom (MDOF) systems, and the pounding was simulated using the modified linear viscoelastic model. The analysis was conducted in two cases: probabilistic analysis and deterministic analysis. Probability curves were established to analyze the effect of the variability of the parameters on the responses of the two colliding buildings. The comparison between the two analyses indicates that the probabilistic analysis is more precise than the deterministic analysis. It has been indicated that taking into account the variability of structural parameters, soil parameters, and seismic action is efficient in determining the realistic behavior of colliding buildings. Additionally, pounding is more critical in the case of buildings founded on very soft soil, followed by those on soft soil, then on hard soil, and finally on rocky soil.
... It is well understood that generalizing the findings from in-person (or virtual) inspections requires systematic analysis of the collected data. This has led to numerous studies in the literature on the statistical (or quantitative trend) analysis of the damage to specific system or component types, including bridges (Baso¨z et al., 1999), non-structural elements (Giaretton et al., 2016), and buildings (Aguilar et al., 1989;Boatwright et al., 2015;Ju¨nemann et al., 2015;Scholl, 1974;Sun and Zhang, 2011). A typical analysis of this type would quantify the empirical distribution of specific types of damage and establish associative relationships (qualitative and quantitative) with potential causal factors (i.e. ...
Collecting and analyzing observational data are essential to learning and implementing lessons in earthquake engineering. Historically, the methods that have been used to analyze and draw conclusions from empirical data have been limited to traditional statistics. The models developed using these techniques are able to capture associative relationships between important variables. However, the intervention decisions geared toward seismic risk mitigation should ideally be informed by an understanding of the causal mechanisms that drive infrastructure performance and community response. This article advocates for a paradigm shift in earthquake engineering where the language, tools, and models that have been (and continue to be) developed to draw causal conclusions from observational data are adopted. Several categories of data-driven earthquake engineering problems that can benefit from causal insights are examined. Two widely adopted frameworks from the broader causal inference literature are presented and linked to hypothetical earthquake engineering problems. The critical role of semi-parametric models and sensitivity analysis in justifying causal claims is also discussed. The article concludes with a discussion of specific opportunities and challenges toward the widespread use of causal inference as a tool for knowledge discovery in earthquake engineering. The ability to leverage the underlying physics of a problem within a causal inference framework is identified as both an opportunity and challenge for earthquake engineering researchers.
... By laminating existing columns with a layer of RC, composite columns are obtained, providing a lateral load-carrying system with better load capacity [3]. After the 1985 El Centro earthquake, this was the preferred alternative for retrofitting of many medium-rise structures affected by this seismic event [4]. As with every other method, this approach has some pros and cons, e.g., while it is beneficial in providing a uniform increase in strength and stiffness [5], it involves severe disruption to the building's inhabitants during the construction [3]. ...
This study aims to select an eco-friendly earthquake-resistant design using life-cycle assessments (LCAs). The study compares LCAs of three retrofitting cases: concrete shear-wall strengthening (Case 1); reinforced concrete column jacketing with shear-wall strengthening (Case 2); and high-damping rubber bearing base isolation with viscous fluid damping devices (Case 3). These cases were applied to a five-story reinforced concrete building built according to the design principles widely used in Israel in the 1970s. The seismic-bearing capacity of the retrofitted building was improved in all three cases, where Case 3 was observed as being the most effective retrofitting measure. The environmental performance of the retrofitting measures was assessed using the ReCiPe 2016 midpoint, which indicated that Case 3 was the best with the least environmental impact, Case 1 was intermediate with moderate environmental impact, and Case 2 was the worst with the most environmental impact. However, the ReCiPe 2016 endpoint single-score results showed that Case 3 caused significantly less damage than Cases 1 and 2, which caused similar significant environmental damage. These results indicate that LCA should be used to select an eco-friendly earthquake-resistant design.
... Pounding can lead to the generation of a high-impact force that may cause either architectural or structural damage. Some reported cases of pounding include i) The earthquake of 1985 in Mexico City [37] that left more than 20% of buildings damaged, ii) Loma Prieta earthquake of 1989 [38] that affected over 200 structures, iii) Chi-Chi earthquake of 1999 [39] in central Taiwan, and iv) Sikkim earthquake (2006) [40]. Methods such as Rapid Visual Screening (RVS), seismic risk indexes, and vulnerability assessments have been developed to analyze the level of damage to a building [41]. ...
Unmanned Aerial Vehicle (UAV) based remote sensing system incorporated with computer vision has demonstrated potential for assisting building construction and in disaster management like damage assessment during earthquakes. The vulnerability of a building to earthquake can be assessed through inspection that takes into account the expected damage progression of the associated component and the component's contribution to structural system performance. Most of these inspections are done manually, leading to high utilization of manpower, time, and cost. This paper proposes a methodology to automate these inspections through UAV-based image data collection and a software library for post-processing that helps in estimating the seismic structural parameters. The key parameters considered here are the distances between adjacent buildings, building plan-shape, building plan area, objects on the rooftop and rooftop layout. The accuracy of the proposed methodology in estimating the above-mentioned parameters is verified through field measurements taken using a distance measuring sensor and also from the data obtained through Google Earth. Additional details and code can be accessed from https://uvrsabi.github.io/ .
It is well known that steel structures have high ductility capacity and high strength to weight ratio, which, theoretically, by nature makes them, the most efficient seismic structural system against strong earthquakes. However, the recorded experience of failures which have befallen over the last 40 years, as a result of strong seismic actions, suggests that this by itself isn't always sufficient. Generally, it is essential that an appropriate and preferred conformation and configuration of the structural system and in particular of its joints should be adopted. In any case, the steel building structures showed local failures without general and complete collapses. The work in this paper presents the seismic performance focused on steel building structures, as revealed by strong earthquakes, such as those of Mexico (1985), Northridge (1994), USA, Kobe (1995), Japan, Christchurch (2010-2011), N. Zealand, which affected and changed the design of metal structures, as well as other earthquakes like Maule (2010), Chile, Emilia (2012), Amatrice (2016), Italy, which completed the picture in the better understanding of failures and their reasons. On the basis of the lessons learnt from, a discussion for avoiding such situations are commented on and provided in this work.
Unmanned Aerial Vehicle (UAV) based remote sensing system incorporated with computer vision has demonstrated potential for assisting building construction and in disaster management like damage assessment during earthquakes. The vulnerability of a building to earthquake can be assessed through inspection that takes into account the expected damage progression of the associated component and the component’s contribution to structural system performance. Most of these inspections are done manually, leading to high utilization of manpower, time, and cost. This paper proposes a methodology to automate these inspections through UAV-based image data collection and a software library for post-processing that helps in estimating the seismic structural parameters. The key parameters considered here are the distances between adjacent buildings, building plan-shape, building plan area, objects on the rooftop and rooftop layout. The accuracy of the proposed methodology in estimating the above-mentioned parameters is verified through field measurements taken using a distance measuring sensor and also from the data obtained through Google Earth. Additional details and code can be accessed from https://uvrsabi.github.io/.
Insufficient or no separation gap between adjacent buildings leads to seismic pounding during the earthquake. The seismic pounding is defined as the collision of the adjacent buildings amid the earthquakes. This type of seismic-induced pounding between closely spaced buildings accumulates the damages, as well as hampers the structural safety under earthquake loads. This paper aims at studying the proper required mitigation techniques to prevent seismic-induced pounding between the adjacent reinforced concrete (RC) buildings by equivalent static force method (ESFM), response spectrum method (RSM) and nonlinear dynamic time history method (NLTHM). The variation of seismic responses like base shear, time period, shear force, bending moment, storey drift and storey displacement with different equal area steel sections of the bracing and its arrangements is investigated, and finally, the best suitable bracing is concluded. Thereupon, its effectiveness in mitigating seismic pounding between two adjacent reinforced concrete buildings is studied by comparing the required separation with and without bracing.KeywordsSeismic poundingTwo adjacent RC buildingsSteel bracingEarthquake
Purpose
Tehran’s health-care system is growing, yet it lacks emergency planning procedures. The premise of this study is that the urban environment around a hospital is just as robust as the hospital itself. This study aims to look at hospital resilience in an urban setting to see where it may be improved to keep the hospital operational during a disaster.
Design/methodology/approach
The urban resilience (UR) of Amir-Alam Hospital was analyzed in this study using a customized version of the United Nations Office for Disaster Risk Reduction’s City Resilience Profiling Tool. The 34 indications were broken down into five categories.
Findings
The result revealed that the hospital’s UR score was 51.75 out of 100, indicating medium resilience. The results of this study enable the decision-makers to determine what measures they may take to improve the hospital’s resilience in terms of its surrounding urban context.
Originality/value
The originality of this research is based on the surrounding urban environment’s resilience as an integral part of hospital resilience.
ResearchGate has not been able to resolve any references for this publication.