Study of vertical seismic isolation technique with nonlinear viscous dampers for lateral response reduction

2019 ◽  
Vol 23 ◽  
pp. 144-154 ◽  
Author(s):  
Reza Milanchian ◽  
Mahmood Hosseini
Keyword(s):  
Seismic Isolation ◽  
Viscous Dampers ◽  
Isolation Technique ◽  
Lateral Response

Geotechnical Seismic Isolation System - Experimental Study

2010 ◽  
Vol 163-167 ◽  
pp. 4449-4453
Author(s):  
Wei Xiong ◽  
Hing Ho Tsang ◽  
S.H. Lo ◽  
Shou Ping Shang ◽  
Hai Dong Wang ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Dynamic Performance ◽  
Testing Procedure ◽  
Shaking Table ◽  
Isolation System ◽  
Isolation Technique ◽  
Sand Mixture ◽  
Seismic Hazard Mitigation ◽  
Constituent Material ◽  
Different Levels

In this study, an experimental investigation program on a newly proposed seismic isolation technique, namely “Geotechnical Seismic Isolation (GSI) system”, is conducted with an aim of simulating its dynamic performance during earthquakes. The testing procedure is three-fold: (1) A series of cyclic simple shear tests is conducted on the key constituent material of the proposed GSI system, i.e., rubber-sand mixture (RSM) in order to understand its behavior under cyclic loadings. (2) The GSI system is then subjected to a series of shaking table tests with different levels of input ground shakings. (3) By varying the controlling parameters such as percentage of rubber in RSM, thickness of RSM layer, coupled with the weight of superstructure, a comprehensive parametric study is performed. This experimental survey demonstrates the excellent performance of the GSI system for potential seismic hazard mitigation.

Evaluation of the Isolation System Influence in the Seismic Loading Analysis Applied to a Near Term Deployment Reactor

2009 ◽  
Author(s):  
R. Lo Frano ◽  
G. Forasassi
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Seismic Waves ◽  
Base Isolation ◽  
Methodological Approach ◽  
Response Spectra ◽  
Three Dimensional Model ◽  
Isolation System ◽  
Isolation Technique ◽  
Near Term

Nuclear power plant (NPP) design is strictly dependent on the seismic hazards and safety aspects related to the external events of the site. Passive vibration isolators are the most simple and reliable means to protect sensitive equipment from environmental shocks and vibrations. This paper concerns the methodological approach to treat isolation applied to a near term deployment reactor and its internals structures in order to attain a suitable decrease of response spectra at each floor along the height of the structure. The aim of this evaluation is to determine the seismic resistance capability of as-built structures systems and components in the event of the considered Safe Shutdown earthquake (SSE). The use of anti-seismic techniques, such as seismic isolation (SI) and passive energy dissipation, seems able to ensure the full integrity and operability of important structures and systems even in very severe seismic conditions. Therefore the seismic dynamic loadings, propagated up to the main reactor system and components, may be reduced by using the developed base-isolation system (high flexibility for horizontal motions) that might combine suitable dampers with the isolating components to support reactor structures and building. To investigate and analyze the effects of the mentioned earthquake on the considered reactor internals, a deterministic methodological approach, based on the evaluation of the propagation of seismic waves along the structure, was used. To the purpose of this study a numerical assessment of dynamic structural response behaviour of the structures was accomplished by means of the finite element approach and setting up, as accurately as possible, a representative three-dimensional model of mentioned NPP structures. The obtained results in terms of response spectra (carried out from both cases of isolated and not isolated seismic analyses) were compared in order to highlight the isolation technique effectiveness.

scholarly journals Research on Structural Design of an Isolated High-Rise Building with Enlarged Base and Multiple Tower Layer in High-Intensity Area

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Haotian Zhang ◽  
Fuju Li ◽  
Ji Tai ◽  
Jun Zhou
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
High Intensity ◽  
Seismic Isolation ◽  
Layer Structure ◽  
Structural Characteristics ◽  
Effective Means ◽  
Isolation Technique ◽  
High Rise ◽  
High Rise Building

In the high intensity areas, the application of interlayer spacing technology can achieve the unity of quality and seismic performance of high-rise buildings with enlarged base and multiple tower layers. Through the comparison and analysis of the structural schemes of an enlarged base multiple tower-layer high-rise building, the ultimate seismic isolation scheme was adopted, and its seismic response and seismic performance were analyzed and studied. The results show that the overall seismic isolation effect of the story isolation technique is good, which can greatly reduce the seismic response, and is an effective means to improve the seismic safety of the structure. Considering the structural characteristics of the project, the improvement of the economy and the quality of the building, the use of story isolation technique in the enlarged base multiple tower-layer structure in the high-intensity region is an optimal scheme. Finally, several key technical issues such as the combined seismic isolation scheme of the enlarged base story isolation technique and the additional bending moment of the isolator and the tensile device of the isolator were discussed, which can provide some references for similar engineering practices.

scholarly journals Seismic Base Isolation System using Scrap Old Tyres

2020 ◽  
Vol 5 (3) ◽  
pp. 85-90
Keyword(s):  
Seismic Isolation ◽  
Structural Engineering ◽  
Base Isolation ◽  
Shock Propagation ◽  
Analysis Tool ◽  
Element Analysis ◽  
Isolation System ◽  
Isolation Technique ◽  
Base Isolation System ◽  
Seismic Vibrations

Enfeebling the effects of vibration caused by the movement of tectonic plates has been the major topic of research in the field of Structural Engineering. Base isolation is a technique used to counteract the effects of seismic vibration and ensuring the safety of the superstructure. Even though, the strategy of base isolation has been used in interminable number of structures, there is a need for economized, effective base isolation technique. India has been recycling and reusing waste tyres for four decades, it is estimated that 60% are disposed of through illegal dumping. India, being the second largest manufacturer of rubber after China, there is a menace of rubber disposal in the country. Despite the numerous efforts of technologists of recycling and utilizing the scrap rubber tyres, 17% of the scrap rubber tyres are diverted to landfill creating disposal problem. Therefore, there is a need for utilizing the used scrap rubber tyres in an innovative way instead of dumping it. Scrap Rubber tyres, being elastic in nature serve to be a potential shock absorber of seismic vibrations. In the present study, an attempt is made to utilize the recycled scrap rubber tyre in seismic isolation of structure. This technique proves to be a low- cost earthquake mitigation technique which can potentially reduce the damage caused by seismic shock propagation into the structure and hence ensure overall safety of the structure. An experimental analysis is done to evaluate the properties of assembly of rubber tyres and utilization of the same for isolating base of structures to check for the effectiveness in enfeebling the shocks produced by seismic vibrations. Furthermore, using the properties of scrap rubber tyres obtained from the experimental results, performance of the scrap tyres as a base isolation system for a multistoried building and stability of the structure was studied using Finite element analysis tool.

scholarly journals Evaluating Collapse Fragility Curves for Existing Buildings Retrofitted Using Seismic Isolation

2020 ◽  
Vol 10 (8) ◽  
pp. 2844
Author(s):  
Amedeo Flora ◽  
Giuseppe Perrone ◽  
Donatello Cardone
Keyword(s):  
Seismic Isolation ◽  
Failure Modes ◽  
Base Isolation ◽  
Fragility Curves ◽  
Limit State ◽  
Spectral Acceleration ◽  
Existing Buildings ◽  
Isolation System ◽  
Isolation Technique ◽  
Design Earthquake

Few studies have investigated so far the collapse capacity of buildings with base-isolation. In such studies, preliminary considerations have been drawn based on a number of assumptions regarding: (i) the methodology used for assessing the collapse capacity, (ii) the collapse conditions and failure modes assumed for both superstructure and isolation system, and (iii) the numerical modeling assumptions. The main results pointed out that the collapse conditions of base-isolated buildings may occur for intensity levels slightly higher than those associated with the design earthquake. In this paper, further developments are made through the use of enhanced models for the description of the behavior of a rubber-based isolation system and the assumption of more rational collapse conditions. Collapse fragility functions, in terms of mean and dispersion values, are proposed for two archetypes representative of existing buildings retrofitted using the seismic isolation technique. The collapse margin ratio (median collapse capacity Sa,C, namely the spectral acceleration associated to a probability of exceedance equal to 50%, divided by the design spectral acceleration at the collapse prevention limit state) has been evaluated for each examined case-study. Values ranging from 1.10 to 1.45 were found.

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 Seismic Isolation System using U-Shaped Steel Damper

2019 ◽  
Vol 8 (4) ◽  
pp. 12336-12339
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Structural Response ◽  
Time History ◽  
Earthquake Ground Motion ◽  
Isolation System ◽  
Isolation Technique ◽  
Base Isolation System ◽  
The Time Domain ◽  
External Forces

In the present paper base isolation system is analyzed and its seismic behavior is investigated using U-shaped steel dampers as an isolator by placing it at the bottom of the structure. It is the most popular way of protecting the structure using control techniques for earthquake ground motion. The dampers significantly reduced damage factors such as displacement and drift. To reduce structural response to external forces, which can be accomplished through the use of special protective systems. So to prevent these damages, seismic isolation technique can be used for newly constructed structures. The time history analysis of the time domain on this structure is conducted by using SAP2000 software

scholarly journals Advanced Modelling and Risk Analysis of RC Buildings with Sliding Isolation Systems Designed by the Italian Seismic Code

2021 ◽  
Vol 11 (4) ◽  
pp. 1938 ◽  
Author(s):  
Felice Carlo Ponzo ◽  
Antonio Di Cesare ◽  
Alessio Telesca ◽  
Alberto Pavese ◽  
Marco Furinghetti
Keyword(s):  
Risk Analysis ◽  
Seismic Isolation ◽  
Limit State ◽  
Seismic Intensity ◽  
Intensity Level ◽  
Isolation System ◽  
Isolation Technique ◽  
Existing Building ◽  
Displacement Capacity ◽  
Ultimate Displacement

Double Curved Concave Surface Sliders (DCCSS) are seismic isolators based on the pendulum principle widely used worldwide. Coherently with European code, DCCSS do not include any mechanical elements as end-stopper. In case of displacement higher than those associated with the design earthquakes, the inner slider runs on the edge of the sliding surfaces beyond their geometric displacement capacity keeping the ability to support gravity loads. In this paper, the advanced modelling and risk analysis of reinforced concrete (RC) base-isolated buildings designed for medium and high seismicity zones according to the Italian code has been assessed considering new construction and existing structures retrofitted using the seismic isolation technique. Pushover analyses and nonlinear dynamic analyses including inelastic superstructure behaviour and the over-stroke displacement of the isolation system have been carried out. Annual rates of failure are computed for Usability-Preventing Damage (UPD) related to the superstructure inter-storey drift and for Global Collapse (GC) associated with the ultimate displacement of the DCCSS. Moreover, the ultimate displacement is assumed with an extra-displacement of more than 30% of the maximum geometrical displacement. Results pointed out that in the case of new buildings the GC and UPD conditions occur almost at the same seismic intensity, while for the cases of the existing building, the UPD is the dominant limit state, being reached at an intensity level lower than GC.

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