Some Retrofit Options for the Seismic Upgrading of Old Low-Rise School Buildings in Mexico

1996 ◽  
Vol 12 (4) ◽  
pp. 883-902 ◽  
Author(s):  
Arturo Tena-Colunga
Keyword(s):  
Mexico City ◽  
Pacific Coast ◽  
Longitudinal Direction ◽  
Soil Conditions ◽  
School Buildings ◽  
Mexican Pacific ◽  
Acceleration Time Histories ◽  
Lead Rubber Bearings ◽  
Time Histories ◽  
Rubber Bearings

An analytical study regarding the seismic upgrading of typical 60's and 70's designs for public school buildings in Mexico is presented. Some schools with these designs were moderately damaged during the 1985 Michoacán Earthquake in Mexico City. The damage was primarily observed in their longitudinal direction where existing slender RC columns have their weak axis. In addition, these columns are confined and shortened by masonry walls that do not run all the story height. These walls are supposed to be non-structural components, however, they experienced shear cracking during the quake due to the distress of the confined columns. Some school buildings were retrofitted after the Michoacán Earthquake adding post-tensioned bracing systems composed of prestressed high-slenderness steel strands (tension-only bracing systems), a retrofit option that is economical. In fact, there is an interest on assessing the effectiveness of this retrofit scheme in other regions with different soil conditions, as for example, the hard soils of the Mexican Pacific Coast. Therefore, the post-tensioning retrofit scheme used for the school buildings in Mexico City was also evaluated for hypothetical locations in the Mexican Pacific Coast. Another option that seems economical for the seismic retrofit of old school buildings in the Mexican Pacific Coast is the use of base isolators. Then, a retrofit plan using lead-rubber bearings was also evaluated. Acceleration time-histories recorded in the Mexican Pacific Coast during the 1985 Michoacán and the 1995 Manzanillo Earthquakes were used to assess the effectiveness of the studied retrofit schemes. Records in Mexico City for the 1985 Michoacán Earthquake and postulated ground motions for a Ms = 8.1 earthquake in Mexico City were also used. The effectiveness of each retrofit scheme is discussed through the comparison of the seismic behavior of original and retrofit structures using a comprehensive set of analyses.

Seismic Isolation of Buildings Subjected to Typical Subduction Earthquake Motions for the Mexican Pacific Coast

1997 ◽  
Vol 13 (3) ◽  
pp. 505-532 ◽  
Author(s):  
Arturo Tena-Colunga ◽  
Consuleo Gómez-Soberón ◽  
Abel Mun~oz-Loustaunau
Keyword(s):  
Dynamic Stability ◽  
Pacific Coast ◽  
Base Isolation ◽  
Time History ◽  
Mode Shapes ◽  
Soil Conditions ◽  
Original Design ◽  
Mexican Pacific ◽  
Fixed Base ◽  
Isolation Systems

An analytical study on the application of different base isolation systems for original design or retrofit of typical building structures of the Mexican Pacific Coast is presented. The subject hypothetical buildings are located on hard soil conditions at Acapulco. Typical accelerograms for the Mexican subduction zone recorded during recent earthquakes were used for 3-D time-history analyses. Bidirectional input was used for the time-history analyses. The studied base isolation systems reported in this study are lead-rubber bearings (LRB) and steel-hysteretic dampers (SHD). For the original design case studies, the superstructures were designed: a) according to the seismic provisions of the building code of Guerrero state (RCGS-90) for the fixed-base condition and, b) according to an elastic design based upon a 3-D lateral force distribution consistent with dominant mode shapes for the isolated structure to yield the peak dynamic base shear transmitted by the isolation system. Material volumes for the superstructure were estimated for both the fixed-base code designs and the base-isolation designs. Important savings on the volume of concrete and steel reinforcement can be attained for the base isolated designs with respect to their counterpart fixed-base designs. Dynamic responses for the isolated structures compare favorably with those for the fixed-base structures. The study confirms many findings published in the literature regarding the effectiveness of base isolation and the effect of torsional responses. However, the study also shows that the dynamic stability of isolators is not always achieved using rational design procedures. The dynamic stability and design of the studied base isolators can be controlled by acceleration records associated to moderate earthquakes when these records are near the fault plane and by torsional responses.

Research on Isolated Strengthening of Erose School Buildings

2011 ◽  
Vol 94-96 ◽  
pp. 1298-1303
Author(s):  
Xi Sen Fan ◽  
Shu Zhen Ren
Keyword(s):  
Seismic Response ◽  
Masonry Structure ◽  
School Buildings ◽  
Isolation System ◽  
Torsional Response ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Lead Rubber Bearings ◽  
Rubber Bearings ◽  
Strengthening Technique

The aseismatic strengthening technique for masonry structure was researched in this paper. The seismic response of a L-type school building with and without isolation system were computed by using software SAP2000. The isolation system were made up of lead rubber bearings or combined Isolation system. The results showed that base-isolated strengthening can reduce not only the translational response but also the torsional response with earthquake. The combined Isolation system was more effetive in decreasing translational response than the lead rubber bearing, but inferior to in decreasing torsion response.

scholarly journals EFFECT OF BASE ISOLATION ON MULTISTOREY STEEL STRUCTURE IN DIFFERENT SOIL CONDITIONS.

2021 ◽  
Vol 10 (3) ◽  
pp. 38-46
Keyword(s):  
Base Isolation ◽  
Steel Structure ◽  
Soil Condition ◽  
Soil Conditions ◽  
Building Structures ◽  
Lead Rubber Bearings ◽  
Predetermined Level ◽  
Leading Position ◽  
Potential Damage ◽  
Rubber Bearings

A quake is a random tremor or movement of the earth’s crust, which is developed naturally on or below the surface of earth. While designing a structures in seismically active area, a designer has to make provision of predetermined level of reliability and earthquake resistance of building structures. Now, to improve the seismic resistance, various isolation techniques, including lead rubber bearings, which occupy a leading position in the construction practice utilization, are being increasingly applied. Base isolation (BI) system for buildings is introduced to separate the building structure from potential damage induced by earthquake motion, preventing the building superstructures from absorbing the earthquake energy. A study determining the effectiveness of base isolators is carried out on multi-storey structures with varying height and in different soil condition.

Formulations of Equivalent Linearization of Lead-Rubber Bearings for Incorporating the Effect of Lead Core Heating

2015 ◽  
Vol 31 (1) ◽  
pp. 317-337 ◽  
Author(s):  
Gökhan Özdemir
Keyword(s):  
Near Field ◽  
Time History ◽  
Hysteretic Behavior ◽  
Soil Conditions ◽  
Equivalent Linearization ◽  
Equivalent Damping ◽  
Nonlinear Time History Analyses ◽  
Lead Rubber Bearings ◽  
Rubber Bearings ◽  
Nonlinear Time History

In this paper, new formulations to calculate equivalent damping ratios used in equivalent linear analysis of seismic-isolated structures, specifically isolated with lead-rubber bearings (LRBs), are proposed. These formulations are capable of incorporating the variation in LRB hysteretic behavior due to reduced bearing strength as a function of lead core heating. To quantify the accuracy of the proposed equations in predicting the maximum isolator displacements (MIDs), MIDs obtained from an extensive number of nonlinear time history analyses (NTHAs) were compared with predicted ones. NTHAs were conducted with two sets of near-field ground motions recorded at different soil conditions. It was found that different formulations are needed to calculate the equivalent LRB damping ratios for the two considered ground motion sets. It was also found that the proposed equations result in highly accurate MID estimations, regardless of isolator characteristics, soil properties, or seismicity levels.

Seawater desalination in Mexican Pacific coast by a new technology: use and perspectives

2012 ◽  
Vol 51 (1-3) ◽  
pp. 175-183
Author(s):  
V. Perez-Moreno ◽  
C.B. Bonilla-Suarez ◽  
M.E. Rodriguez-Muñoz
Keyword(s):  
Technology Use ◽  
Pacific Coast ◽  
New Technology ◽  
Seawater Desalination ◽  
Mexican Pacific

Spatial and seasonal variation in littoral fish assemblages of four estuarine lagoons on the Mexican Pacific coast

2021 ◽  
pp. 102000
Author(s):  
Yureidy Cabrera-Páez ◽  
Consuelo M. Aguilar-Betancourt ◽  
Gaspar González-Sansón ◽  
Angel Hinojosa-Larios
Keyword(s):  
Seasonal Variation ◽  
Pacific Coast ◽  
Fish Assemblages ◽  
Mexican Pacific ◽  
Littoral Fish ◽  
Spatial And Seasonal Variation

Metrics for the Comparison of Acceleration Time Histories

2017 ◽  
Author(s):  
Nithyagopal Goswami ◽  
Mourad Zeghal ◽  
Majid Manzari ◽  
Bruce Kutter
Keyword(s):  
Acceleration Time ◽  
Acceleration Time Histories ◽  
Time Histories

Simplified Criteria to Select Ground Response Analysis Methods for Seismic Building Design: Equivalent Linear versus Nonlinear Approaches

2021 ◽  
Author(s):  
Mauro Aimar ◽  
Sebastiano Foti
Keyword(s):  
Seismic Waves ◽  
Site Response ◽  
Building Design ◽  
Soil Conditions ◽  
Response Analysis ◽  
Depth Range ◽  
Ground Response Analysis ◽  
Equivalent Linear ◽  
Acceleration Time Histories ◽  
Soil Deposits

ABSTRACT The possible amplification of seismic waves in soil deposits is crucial for the seismic design of buildings and geotechnical systems. The most common approaches for the numerical simulation of seismic site response are the equivalent linear (EQL) and the nonlinear (NL). Even though their advantages and limitations have been investigated in several studies, the relative field of applicability is still under debate. This study tested both methods over a wide population of soil models, which were subjected to a set of acceleration time histories recorded from strong earthquakes. A thorough comparison of the results of the EQL and the NL approaches was carried out, to identify the conditions in which the relative differences are significant. This assessment allowed for the definition of simplified criteria to predict when the two schemes are or are not compatible for large expected shaking levels. The proposed criteria are based on simple and intuitive parameters describing the soil deposit and the ground-motion parameters, which can be predicted straightforwardly. Therefore, this study provides a scheme for the choice between the EQL and the NL approaches that can be used even at the preliminary design stages. It appears that the EQL approach provides reliable amplification estimates in soil deposits with thickness up to 30 m, except for very deformable soils, but this depth range may be extended at long vibration periods. This result reveals a good level of reliability of the EQL approach for various soil conditions encountered in common applications, even for high-intensity shaking.

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