The Mexico Earthquake of September 19, 1985—Seismic Zoning of Mexico City after the 1985 Earthquake

1989 ◽  
Vol 5 (1) ◽  
pp. 257-271 ◽  
Author(s):  
J. Iglesias
Keyword(s):  
Mexico City ◽  
Soft Soil ◽  
Resistance Coefficient ◽  
Seismic Zoning ◽  
Base Shear ◽  
Severe Damage ◽  
Seismic Capacity ◽  
Mexico Earthquake ◽  
The City ◽  
Resistance Coefficients

Using a simplified method for the evaluation of the seismic capacity of medium rise concrete structures, it was possible to obtain the base shear coefficient corresponding to failure (resistance coefficient) for 162 buildings, and use it as an evaluation index. The resistance coefficients of the 90 evaluated structures that suffered severe damage were used to elaborate a map of intensities for the 1985 Mexico City earthquake. This map shows the strong interaction of neighboring zones of firm soil or rock that amplify the ground motion in the soft soil between them as much as 100%, this being the main reason for the high intensities observed in some districts of the city. Based on these results, a new seismic zoning was proposed for the chapter of the 1987 Mexico City Building Code.

The Mexico Earthquake of September 19, 1985—Evaluation of the Seismic Capacity of Buildings in Mexico City

1989 ◽  
Vol 5 (1) ◽  
pp. 19-24 ◽  
Author(s):  
F. Noren~a ◽  
C. Castan~eda ◽  
J. Iglesias
Keyword(s):  
Mexico City ◽  
Seismic Capacity ◽  
Preventive Actions ◽  
Mexico Earthquake ◽  
The City ◽  
Selection Of

As a consequence of the 1985 Mexico City earthquake, the authorities of the city have decided to evaluate the seismic capacity of the buildings without damage with the purpose of detecting those with the most vulnerability, in order to take the preventive actions necessary to improve the security of the citizens in future earthquakes. Based on the census of the structures of the city, the procedure of evaluation used considers three levels of increasing precision permitting a progressive selection of the buildings in bad condition. Work is now under process in the main districts of the city with good results.

scholarly journals Subsoil Characteristics of Mexico City, acceleration and hysteretic energy spectra for the Mexico Earthquake of September 19, 2017

2020 ◽  
Vol 59 (4) ◽  
pp. 234-256
Author(s):  
Pablo Quinde ◽  
Eduardo Reinoso
Keyword(s):  
Mexico City ◽  
Spectral Ratios ◽  
Severe Damage ◽  
Local Effects ◽  
Hysteretic Energy ◽  
Intraslab Earthquake ◽  
Fourier Spectra ◽  
Mexico Earthquake ◽  
Energy Maps ◽  
The City

The September 19, 2017 intraslab earthquake (Mw7.1), whose epicenter was located near the limits between the states of Puebla and Morelos at approximately 120km from Mexico City, caused severe damage in these regions. In Mexico City more than 40 buildings collapsed, and hundreds had moderate to severe damage; dozens of them are to be demolished. This article analyzes the spectral ratios of accelerometric stations in the lake-bed of Mexico City with respect to the average Fourier spectra at hill zone sites in order to study and compare over time the changes in the behavior of local effects and their relationship with the damage presented during this earthquake; these ratios exhibit also the settlement problem in some places in the city due to over exploiting the aquifer for water supply purposes. Finally, pseudoacceleration and hysteretic energy maps for Mexico City with a discussion with a possible correlation with reported damages are presented.

The Mexico Earthquake of September 19, 1985—Case Studies of Seismic Strengthening for Two Buildings in Mexico City

1989 ◽  
Vol 5 (1) ◽  
pp. 153-174 ◽  
Author(s):  
D. A. Foutch ◽  
K. D. Hjelmstad ◽  
E. Del Valle Calderón ◽  
E. Figueroa Gutiérrez ◽  
R. E. Downs
Keyword(s):  
Reinforced Concrete ◽  
Mexico City ◽  
Reinforced Concrete Frame ◽  
Concrete Walls ◽  
Concrete Frame ◽  
Reinforced Concrete Walls ◽  
Steel Bracing ◽  
Geotechnical Investigations ◽  
Mexico Earthquake ◽  
The City

The earthquake that shook Mexico City on 19 September 1985, destroyed several hundred buildings and took thousands of lives. Two buildings located in the most highly damaged part of the city experienced strong shaking, but suffered only slight damage. These reinforced concrete frame buildings had been retrofit with steel bracing systems and infill reinforced concrete walls prior to the earthquake. Forced vibration tests, analytical studies and geotechnical investigations for each building have been conducted. The results indicate that the steel bracing systems strengthened the buildings and stiffened them, moving their natural periods away from the 2.0-second predominant ground period in that part of the city. Implications for the design of strengthening systems have been determined.

The Mexico Earthquake of September 19, 1985—Performance of Low-Rise Buildings in Mexico City

1989 ◽  
Vol 5 (1) ◽  
pp. 121-143 ◽  
Author(s):  
E. Miranda ◽  
V. V. Bertero
Keyword(s):  
Reinforced Concrete ◽  
Mexico City ◽  
Soft Soil ◽  
Time History ◽  
Federal District ◽  
Excellent Performance ◽  
Soil Zone ◽  
Space Frames ◽  
Dynamic Analyses ◽  
Mexico Earthquake

This paper summarizes the results of analytical studies conducted to understand the observed performance of low-rise buildings located in the soft-soil zone of Mexico City during the 1985 Michoacan earthquake. Two low-rise reinforced concrete moment resistant space frames were designed in accordance with the 1976 Code for the Federal District of Mexico. They were subjected to a series of static and time history dynamic analyses. The results indicate that the designed buildings have significantly larger lateral strengths than required by the Code and that these overstrengths were the main reason for the excellent performance of most of the low-rise buildings in Mexico City during the 1985 Michoacan earthquake.

The Mexico Earthquake of September 19, 1985—Response and Design Spectra Obtained from Earthquake-Damaged Buildings

1989 ◽  
Vol 5 (1) ◽  
pp. 113-120 ◽  
Author(s):  
A. Gómez ◽  
R. Ortega ◽  
J. J. Guerrero ◽  
E. González ◽  
J. P. Paniagua ◽  
...  
Keyword(s):  
Mexico City ◽  
Shear Force ◽  
Response Spectrum ◽  
Base Shear ◽  
Natural Period ◽  
Safety Level ◽  
Design Spectrum ◽  
Design Spectra ◽  
Mexico Earthquake ◽  
High Seismicity

The resistant shear force of 13 buildings severely damaged by the 1985 Mexico City earthquake was determined by static and dynamic analyses. The results of the static analysis suggest the advisability of increasing the shear base coefficient of the 1987 Mexico City building code RDF87 from 0.4 to 0.6 in the high seismicity zones of the area. The results of the dynamic analysis show that in order to obtain the same safety level, the maximum ordinate of the design spectrum should be larger than the base shear coefficient used with the static method, leading to a 0.8 maximum ordinate for Mexico City. When the resistant shear force is plotted as a function of the natural period of each building, the response spectrum obtained is very similar to the inelastic spectrum derived from the accelerograms, considering 5% critical damping, a ductility factor of 4 and degradation in resistance from 5% to 10%. Based on these results, new design spectra are proposed for use in the high seismicity zones in Mexico City.

The Mexico Earthquake of September 19, 1985—The Seismic Performance of Buildings with Weak First Storey

1989 ◽  
Vol 5 (1) ◽  
pp. 89-102 ◽  
Author(s):  
S. E. Ruiz ◽  
R. Diederich
Keyword(s):  
Mexico City ◽  
Soft Soil ◽  
Absorption Capacity ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Lateral Resistance ◽  
Lateral Strength ◽  
Mexico Earthquake ◽  
Range Of Values ◽  
Acceleration Record

During the Michoacan earthquake of Séptember 19, 1985, 8 percent of the damaged buildings in the Mexico City area were characterized by a first storey much weaker than the upper ones. Although it is recognized that these failures may have resulted from the combination of several features, in this paper it is intended to study the possible influence of the lateral strength discontinuity in the ductility demand at the first storey, and to try to understand the behaviour of this type of structures under the actions of the East-West component of the highest acceleration record obtained on soft soil in Mexico City during the mentioned earthquake. A parametric study for five and twelve-storey buildings with weak first storey is presented in this paper. The infill walls in the upper storeys were brittle in some cases and ductile in others. For certain cases, the results show the existence of a range of values of the ratio of seismic lateral resistance of the upper storeys to that of the lowest one for which ductility demands at the lowest story can be considerably higher than for other intervals. It is shown that the absorption capacity of ductile walls plays an important role in the displacement ductility demands of the first storey.

Observations of Rayleigh waves in Mexico City Valley during the 19 September 2017 Puebla–Morelos, Mexico earthquake

2020 ◽  
Vol 36 (2_suppl) ◽  
pp. 62-82
Author(s):  
Pablo Heresi ◽  
Jorge Ruiz-García ◽  
Omar Payán-Serrano ◽  
Eduardo Miranda
Keyword(s):  
Surface Waves ◽  
Mexico City ◽  
Edge Effects ◽  
Rayleigh Waves ◽  
Soft Soil ◽  
Inner Product ◽  
Basin Edge ◽  
Literature Evidence ◽  
Mexico Earthquake ◽  
Stockwell Transform

This article discusses the principal features of Rayleigh surface waves generated by basin-edge effects in Mexico City during the Mw7.1 19 September 2017 Puebla–Morelos, Mexico earthquake. Rayleigh waves were extracted from ground motions recorded at 12 stations in Mexico City. We used a recently proposed method for extracting surface waves, where the earthquake record is filtered based on the normalized inner product of the Stockwell transform of the three-component earthquake recordings. Results of this study reveal that basin-edge effects produced strong Rayleigh waves, particularly at certain stations, with frequencies that are mainly between 0.2 and 0.9 Hz, which is consistent with previous frequency ranges reported in the literature. Evidence of higher-mode Rayleigh waves was found at all stations located on soft soil sites, even at stations that are more than 1 km away from the basin edges. It was also observed that peak acceleration spectral ordinates of the retrograde component of the extracted Rayleigh waves at two stations exceeded the design spectral ordinates of the 1976 and 2004 editions of the Mexico City Seismic Provisions.

The Mexico Earthquake of September 19, 1985—Behavior of Building Foundations in Mexico City

1988 ◽  
Vol 4 (4) ◽  
pp. 835-853 ◽  
Author(s):  
M. J. Mendoza ◽  
G. Auvinet
Keyword(s):  
Mexico City ◽  
Soft Soil ◽  
Shear Forces ◽  
Natural Period ◽  
Plastic Deformations ◽  
Long Period ◽  
Cyclic Stresses ◽  
Static Contact ◽  
Mexico Earthquake ◽  
Main Factor

During the 1985 earthquake, a number of building foundations in the lacustrine soft soil area of Mexico City presented an inadequate performance. Previous high static contact stresses between the foundation and the supporting subsoil propitiated the appearance of plastic deformations of the soil under seismic cyclic stresses, which led to settlements and tilting of the buildings. Foundations of all kinds showed different degrees of vulnerability to the earthquake, but constructions on friction piles sustained the most severe damages. This can be attributed in some cases to non compliance with the accepted design criteria and current regulations. The main factor was however the pronounced dynamic magnification of seismic movements associated to the quasi coincidence between the natural period of some structures with moderate height on friction piles, and the long period of the subsoil motions, which led to large overturning moments and shear forces at the foundation level.

The Mexico Earthquake of September 19, 1985—Nonstationary Models of Seismic Ground Acceleration

1988 ◽  
Vol 4 (3) ◽  
pp. 551-568 ◽  
Author(s):  
M. Grigoriu ◽  
S. E. Ruiz ◽  
E. Rosenblueth
Keyword(s):  
Mexico City ◽  
Stationary Process ◽  
Soft Soil ◽  
Nonstationary Process ◽  
Oscillatory Process ◽  
Ground Acceleration ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Coefficients Of Variation ◽  
Mexico Earthquake

Characteristics of a nonstationary process obtained by modulating the amplitude and frequency of a stationary process differ from those of an oscillatory process. An accelerogram recorded in the soft soil of Mexico City during the 1985 earthquake serves to calibrate both nonstationary models. Responses of linear and nonlinear single-degree-of-freedom systems indicate that the process with modulated amplitude and frequency is preferable for reliability studies. Coefficients of variation of ductility demands of systems excited with accelerograms generated by the model with modulated amplitude and frequency are close to those corresponding to actual accelerograms.

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