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.

Dynamic Nonlinear Analysis of an Hybrid Base Isolation System with Viscous Dampers and Friction Sliders in Parallel

2012 ◽  
Vol 234 ◽  
pp. 96-101 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis
Keyword(s):  
Nonlinear Analysis ◽  
Base Isolation ◽  
Three Dimensional ◽  
Time History ◽  
Seismic Action ◽  
Viscous Dampers ◽  
Isolation System ◽  
Fixed Base ◽  
Base Isolation System ◽  
Dynamic Nonlinear Analysis

In the present work we have analyzed a particular base isolation system for the seismic protection of a multi-storey reinforced concrete (RC) building. The viscous dampers and friction sliders are the devices adopted in parallel for realizing the base isolation system. The base isolation structure has been designed and verified according to European seismic code EC8 and by considering for the friction sliders the influence of the sliding velocity on the value of the friction coefficient. A dynamic nonlinear analysis for a three-dimensional base isolated structure has been performed. Recorded accelerograms for bi-directional ground motions have been used which comply with the requirements imposed by EC8 for the representation of a seismic action in a time history analysis. In this paper a comparative analysis is presented between the base isolated structure with the described hybrid base isolation system and the traditional fixed base structure.

Seismic Analysis and Comparison of Different Base Isolation Systems for a Multi-Storey RC Building with Irregularities in Plan

2012 ◽  
Vol 594-597 ◽  
pp. 1788-1799 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis
Keyword(s):  
Base Isolation ◽  
Seismic Analysis ◽  
Cyclic Behavior ◽  
Isolation System ◽  
High Damping Rubber Bearings ◽  
Fixed Base ◽  
Base Isolation System ◽  
High Damping Rubber ◽  
Isolation Systems ◽  
Rubber Bearings

In the present paper the dynamic nonlinear analysis for a 3D base isolated structure is illustrated. A base isolated reinforced concrete building is designed and verified according to the European seismic codes such that the superstructure remains almost completely elastic and the nonlinear elements are localized only in the base isolation system. Nonlinear hysteretic models have been adopted to reproduce the cyclic behavior of the isolators. Two different base isolation systems are considered and their performances are compared for evaluating the behaviour of a base isolated building, highly irregular in plan, in presence of a seismic excitation defined with recorded accelerograms which characterize the bi-directional ground motions. The isolation system has been realized with a combination in parallel of elastomeric bearings and sliding devices. In the first analyzed isolation system we have used the High Damping Rubber Bearings (HDRB) and in the second analyzed isolation system we have used the Lead Rubber Bearings (LRB). Finally a comparative analysis between the base isolated structure with hybrid base isolation systems and the conventional fixed base structure is detailed.

Supplemental dampers in base-isolated buildings to mitigate large isolator displacement under earthquake excitations

2015 ◽  
Vol 48 (2) ◽  
pp. 100-117 ◽  
Author(s):  
Daniel H. Zelleke ◽  
Said Elias ◽  
Vasant A. Matsagar ◽  
Arvind K. Jain
Keyword(s):  
Equations Of Motion ◽  
Time History ◽  
Coupled Equations ◽  
History Analysis ◽  
Base Isolator ◽  
Fixed Base ◽  
Passive Dampers ◽  
Supplemental Dampers ◽  
Isolation Systems ◽  
Storey Building

The effect of viscous, viscoelastic, and friction supplemental dampers on the seismic response of base-isolated building supported by various isolation systems is investigated. Although base-isolated buildings have an advantage in reducing damage to the superstructure, the displacement at the isolation level is large, especially under near-fault ground motions. The influence of supplemental dampers in controlling the isolator displacement and other responses of base-isolated building is investigated using a multi-storey building frame. The coupled equations of motion are derived, solved and time history analysis is carried out on a building modeled with fifteen combinations of five isolation systems and three passive dampers. The seismic responses are compared with that of the fixed-base and base-isolated buildings. Based on the results, it is concluded that supplemental dampers are beneficial to control the large deformation at the isolator level. Parametric study is conducted and optimum ranges of damper parameters to achieve reduced isolator displacement without adverse effect on the other responses are determined. Further, it is concluded that the combination of the resilient-friction base isolator (R-FBI) and viscous damper is the most effective in reducing the bearing displacement without significant increase in superstructure forces.

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.

Comparison between fixed base and isolated base in seismic response of high-rise buildings: a case study

2020 ◽  
Vol 6 (4) ◽  
pp. 204
Author(s):  
Anas M. Fares
Keyword(s):  
Response Spectrum ◽  
Soft Soil ◽  
Structural Response ◽  
Time History ◽  
Soil Condition ◽  
Soil Conditions ◽  
Spectral Acceleration ◽  
Base Shear ◽  
High Rise ◽  
Fixed Base

In this study, the influence of soil condition under the isolated and fixed bases is studied by using ETABS 16 software for the high-rise regular building. A regular building with 10 floors is modeled and the results are obtained for story displacements, story shear forces and spectral acceleration according to Uniform Building Code 97 (UBC-97) code. The time history analysis has been performed by using 1999 Izmit earthquake record. 3 types of soil which had different stiffnesses are considered in this study. The results show that the value of base shear increases when the soil stiffness decreases. It also noticed that the spectral acceleration is larger in soft soil condition than that of other soil conditions; and this confirms that the structural response spectrum is associated with the soil condition. In addition, when using base isolated building the drift of lower floors will be larger than that of using base isolated, but in the upper floors the drifts of fixed base building will be larger than that of the isolated base building. Finally, time history method in the seismic design will produce base shear less than that from equivalent static method, so calibration factor for design purpose shall be used.

Comparative Studies of Base Isolation Systems Featured with Lead Rubber Bearings and Friction Pendulum Bearings

2016 ◽  
Vol 846 ◽  
pp. 114-119
Author(s):  
Arati Pokhrel ◽  
Jian Chun Li ◽  
Yan Cheng Li ◽  
Nicos Maksis ◽  
Yang Yu
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Elastic Base ◽  
Base Shear ◽  
Isolation Technique ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Isolation Systems ◽  
Friction Pendulum

Due to the fact that safety is the major concern for civil structures in a seismic active zone, it has always been a challenge for structural engineers to protect structures from earthquake. During past several decades base isolation technique has become more and more popular in the field of seismic protection which can be adopted for new structures as well as the retrofit of existing structures. The objective of this study is to evaluate the behaviours of the building with different seismic isolation systems in terms of roof acceleration, elastic base shear and inter-storey drift under four benchmark earthquakes, namely, El Centro, Northridge, Hachinohe and Kobe earthquakes. Firstly, the design of base isolation systems, i.e. lead rubber bearing (LRB) and friction pendulum bearing (FPB) for five storey RC building was introduced in detail. The non-linear time history analysis was performed in order to determine the structural responses whereas Bouc-Wen Model of hysteresis was adopted for modelling the bilinear behaviour of the bearings. Both isolation systems increase the fundamental period of structures and reduces the spectral acceleration, and hence reduces the lateral force cause by earthquake in the structures, resulting in significant improvement in building performance; however the Lead Rubber Bearing provided the best reduction in elastic base shear and inter-storey drift (at first floor) for most of the benchmark earthquakes. For the adopted bearing characteristics, FPB provided the low isolator displacement.

scholarly journals Mitigation of Earthquake Responses Using SMA Supplemented Base-Isolation Devices for Benchmark Building

2021 ◽  
Vol 2 (4) ◽  
pp. 22-30
Author(s):  
Ashish R. Akhare
Keyword(s):  
Degrees Of Freedom ◽  
Base Isolation ◽  
Near Field ◽  
Evaluation Criteria ◽  
Time History ◽  
Base Shear ◽  
Comparative Performance ◽  
Isolation System ◽  
Seismic Control ◽  
Isolation Systems

The efficiency of traditional isolation bearings is doubted for near-field earthquakes because these bearings undergo large displacement. A comparative study of different base isolation systems of base-isolated benchmark building is carried out in the present study. The study is based on assumption that buildings are bi-directionally acted upon by near-field earthquakes for assessing their relative performance in seismic control of the benchmark building. The time history variations of important response parameters and evaluation criteria of the benchmark building has been studied for assessing the effectiveness of the isolation systems. The Shape Memory Alloy (SMA) is utilized with elastomeric bearings and friction bearings to study the effectiveness of SMA wires with different isolators. The benchmark building is modelled as a discrete linear elastic shear structure having three degrees of- freedom at each floor level. Time domain dynamic analysis of this building has been carried out with the help of constant average acceleration Newmark’s method and equilibrium of non-linear forces has been taken care by fourth order Runge-Kutta method. The comparative performance of various isolation systems has been studied with uniform and hybrid combinations. The hybrid combination of SMA supplemented bearings works out the better isolation system keeping in view of the percentage reduction in evaluation criteria for smart base-isolated benchmark building. Furthermore, it is shown that, the functionality of SMA wire is not efficient with Lead Rubber Bearing system, as it is able to control displacement but increases the acceleration, base shear, story drift and isolation forces.

Study on Seismic Performance of Symmetrical Steel Framed Building that with and without ERB and FPS Isolators

2012 ◽  
Vol 204-208 ◽  
pp. 2634-2640
Author(s):  
Dong Zhou Xia
Keyword(s):  
Base Isolation ◽  
Linear Time ◽  
Time History ◽  
Cost Effective ◽  
Design Guidelines ◽  
Northridge Earthquake ◽  
Base Shear ◽  
Rubber Bearing ◽  
History Analysis ◽  
Fixed Base

As is known, base isolation can reduce earthquake energy that transferred from the ground motion to the structure by buffering it with a bearing layer at the foundation which has relatively low horizontal stiffness. The paper investigates the time history records of a two storied symmetrical steel framed isolated building with Elastomeric Rubber Bearing and Friction Pendulum Systems that under the Northridge earthquake, and the isolator parameters are calculated using the design guidelines of International Building Code (IBC2000) within the spirit of IS 1893–2002(7). And then, contrasting of the roof’s displacements, accelerations and base shear values of the steel framed building with and without isolators, and which studied from the Non-linear time history analysis using structural analysis software SAP2000. The results show that base isolation will provide a substitute technology for the conventional, fixed-base design of structures and cost-effective for new buildings in high seismic regions.

scholarly journals Response control of structures under Seismic and Blast induced ground motions

2021 ◽  
Vol 309 ◽  
pp. 01137
Author(s):  
Vamshisheela Siripuram ◽  
Atulkumar Manchalwar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Base Shear ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
Isolation Device ◽  
Nonlinear Time History

In the present paper an investigation is carried out to evaluate the efficiency of Base Isolation device in a building subjected to both seismic and blast induced ground motions. A 5-story building is modelled with different story stiffness and floor masses is considered in this study. In SAP 2000 software two buildings, one with fixed base and the other with isolated base are designed and nonlinear time history analysis is conducted. The structural responses of these two models subjected to four recorded earthquakes and four different blast ground accelerations is compared in this study. The base isolated device such as lead/rubber bearing have proved to be effective in reducing the base Shear and Top story acceleration, and also increase in Hysteresis energy in the base isolated structure subjected to seismic and blast vibrations.

scholarly journals Performance of elevated water tank staging with base isolation under blast loading

2021 ◽  
Vol 309 ◽  
pp. 01134
Author(s):  
Boda Balaraju ◽  
Atulkumar Manchalwar
Keyword(s):  
Base Isolation ◽  
Linear Time ◽  
Time History ◽  
Water Tank ◽  
Base Shear ◽  
Isolation Technique ◽  
Underground Blast ◽  
Base Isolator ◽  
Fixed Base ◽  
Elevated Water

In this present study aims to evaluate the performance of base isolation device under different intensity blast induced ground excitations for an elevated water tank staging. In this study mainly focused to improve the performance of the base isolator and minimize the damage of the structure. To know the performance of base isolator two models are considered one is fixed base model and another one is supported with base isolator model for both non-linear time history analysis is carried out with the help of SAP 2000 software subjected to four different underground blast intensities. From the analysis, it is observed that by using base isolator supported model structural responsive parameters such as base shear, top storey accelerations are efficiently reduced when compared to the fixed base structure. Hence it is proved that adopting base isolation technique we considerably reduce the damage of the structure subjected to underground blast vibrations.

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