A Comparative Study on the Seismic Performance of Superelastic-Friction Base Isolators against Near-Field Earthquakes

2012 ◽  
Vol 28 (3) ◽  
pp. 1147-1163 ◽  
Author(s):  
Osman E. Ozbulut ◽  
Stefan Hurlebaus
Keyword(s):  
Seismic Performance ◽  
Near Field ◽  
Time History ◽  
The Other ◽  
Superior Performance ◽  
Base Shear ◽  
Isolation System ◽  
Pendulum System ◽  
Base Isolator ◽  
Isolation Systems

This paper presents a comparative seismic performance assessment of super-elastic-friction base isolator (S-FBI) systems in improving the response of bridges under near-field earthquakes. The S-FBI system consists of a steel-Teflon sliding bearing and a superelastic shape memory alloy (SMA) device. The other isolation systems considered here are lead rubber bearing (LRB), friction pendulum system (FPS), and resilient-friction base isolator (R-FBI). Each isolation system is designed to provide the same isolation period and characteristic strength. Nonlinear time-history analyses of an isolated bridge are performed to compare the performance of various isolation systems. The results indicate that the S-FBI system shows superior performance in reducing deck displacement response and effectively limits permanent bearing deformation, whereas residual deformations are present for the other isolation systems in some cases. It is also observed that the LRB system has the largest deck drifts while the FPS system and R-FBI system produce the smallest peak deck acceleration and base shear.

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.

INFLUENCE OF HIGH INITIAL ISOLATOR STIFFNESS ON THE SEISMIC RESPONSE OF A BASE-ISOLATED BENCHMARK BUILDING

2011 ◽  
Vol 11 (06) ◽  
pp. 1201-1228 ◽  
Author(s):  
AJAY SHARMA ◽  
R. S. JANGID
Keyword(s):  
Degrees Of Freedom ◽  
Base Isolation ◽  
Near Field ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Time History ◽  
Base Shear ◽  
Isolation System ◽  
Base Displacement ◽  
Floor Acceleration

The influence of high initial isolator stiffness on the response of a base-isolated benchmark building is investigated. The base-isolated building is modeled as a three-dimensional linear-elastic structure having three degrees-of-freedom at each floor level. The time-history analysis of this building is carried out by solving the governing equations of motion using Newmark-beta method along with an iterative predictor–corrector approach. The force–deformation behavior of the isolation system is modeled by a bilinear law, which can be effectively used to model all isolation systems in practice. Three near-field earthquakes with bidirectional ground motions are considered. Structural response parameters such as absolute top floor acceleration, base shear, and base displacement are chosen for investigating the effects of high initial isolator stiffness. It was observed that the high initial isolator stiffness of the isolation system excites the higher modes in the base-isolated building and increases the top floor acceleration. Such a phenomenon can be detrimental to the sensitive instruments placed in the isolated structure. On the other hand, both the base displacement and base shear reduce marginally due to increase in the initial isolator stiffness. Further, the influences of high initial isolator stiffness are found to dependent on the period and characteristic strengths of the base isolation system.

On the Effectiveness of Two Isolation Systems for the Seismic Protection of Elevated Tanks

2014 ◽  
Author(s):  
Fabrizio Paolacci
Keyword(s):  
Time History ◽  
Seismic Protection ◽  
Base Shear ◽  
Lumped Mass ◽  
Isolation System ◽  
High Damping Rubber Bearings ◽  
Elevated Tanks ◽  
High Damping Rubber ◽  
Isolation Systems ◽  
Rubber Bearings

This paper deals with the effectiveness of two isolation system for the seismic protection of elevated steel storage tanks. In particular the performance of High Damping Rubber Bearings and Friction Pendulum isolators has been analyzed. As case study an emblematic example of elevated tanks collapsed during the Koaceli Earthquake in 1999 at Habas Pharmaceutics plant in Turkey has been considered. A time-history analysis conducted using lumped mass models demonstrated the high demand in terms of base shear required to the support columns and their inevitable collapse due to the insufficient shear strength. A proper design of HDRB and FPS isolator and a complete non-linear analysis of the isolated tanks proved the high effectiveness of both isolation systems in reducing the response of the case tank. Actually, a reduced level of displacements of isolators and a reduced level of convective base shear obtained with the second isolation typology, suggested the used of FPS isolators rather than HDRB.

scholarly journals EFFECT OF BASE ISOLATOR ON THE STRUCTURAL RESPONSE OF REINFORCED CONCRETE MULTISTORIED BUILDING UNDER SEISMIC LOADS

2017 ◽  
Vol 8 (1) ◽  
pp. 49-56
Author(s):  
Z. Tafheem ◽  
T. A. Arafat ◽  
A. Chowdhury ◽  
A. Iqbal
Keyword(s):  
Reinforced Concrete ◽  
Time History ◽  
Time History Analysis ◽  
Mode Shapes ◽  
Base Shear ◽  
Isolation System ◽  
Time Period ◽  
History Analysis ◽  
Base Isolator ◽  
Structural Responses

This study investigates the effect of base isolator on the structural responses of multistoried reinforced concrete building under time history earthquake loading. In the present study, six-storied reinforced concrete buildings with both conventional and isolated bases have been modeled. Conventional building has been modeled with fixed support whereas base-isolated building has been modeled incorporating rubber bearing near the base of all columns. Modal analysis has been performed to get an idea of possible mode shapes of the building. After that time history analysis has been performed in order to investigate the effect of seismic loading on the building structure with respect to time. The structural responses of time history analysis such as time period of different modes, storey displacements, storey acceleration, and base shear have been obtained from both conventional and base-isolated buildings. Finally, a comparative study of structural responses has been carried out between those two structures. It has been found that fundamental time period of base-isolated building is increased by 28% compared to conventional building. Moreover, base shear value of the base-isolated structure is reduced by 69% and top storey acceleration is decreased by 75% compared to conventional building. This study reveals that isolation system reduces seismic responses significantly.

Analysis of the Seismic Performance of RC Frame Structures with Different Types of Bracings

2012 ◽  
Vol 166-169 ◽  
pp. 2209-2215
Author(s):  
Zhi Xin Wang ◽  
Hai Tao Fan ◽  
Huang Juan Zhao
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Steel Tube ◽  
Frame Structure ◽  
Frame Structures ◽  
Finite Element Models ◽  
Base Shear ◽  
Concrete Filled Steel Tube ◽  
Different Types ◽  
Rc Frame Structures

Finite element models of frames with steel-bracings and with concrete filled steel tube struts are built in ETABS. Seismic performance of these models is analyzed with base-shear method, superposition of modal responses method and time history method respectively. The results show that the steel-bracings or concrete filled steel tube struts are efficient to increase the story-stiffness, and the top displacement of the frame structure decreases significantly.

Effects of Damper Force Ranges and Ground Motion Pulse Periods on the Performance of Semi-Active Isolation Systems

2003 ◽  
Author(s):  
Henri Gavin ◽  
Julie Thurston ◽  
Chicahiro Minowa ◽  
Hideo Fujitani
Keyword(s):  
Ground Motion ◽  
Large Scale ◽  
Base Isolation ◽  
Near Field ◽  
Shaking Table ◽  
Isolation System ◽  
Active Isolation ◽  
Isolation Systems ◽  
Fail Safe ◽  
Strong Ground

A large-scale base-isolated steel structural frame was tested at the shaking table laboratory of the National Research Institute for Earth Sciences and Disaster Prevention. These collaborative experiments featured auto-adaptive media and devices to enhance the performance of passive base isolation systems. The planning of these experiments involved determining appropriate device control methods, the development of a controllable damping device with fail-safe characteristics, and the evaluation of the performance of the controlled isolation system subjected to strong ground motion with pronounced near-field effects. The results of the planning study and their large-scale experimental confirmation provide guidelines for the development and implementation of auto-adaptive damping devices for full scale structures.

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.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 3 — Seismic Response of Crossover Piping for Seismic Isolation System

2014 ◽  
Author(s):  
Akihito Otani ◽  
Teruyoshi Otoyo ◽  
Hideo Hirai ◽  
Hirohide Iiizumi ◽  
Hiroshi Shimizu ◽  
...  
Keyword(s):  
Seismic Response ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Response Spectrum ◽  
Time History ◽  
Response Analysis ◽  
Isolation System ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper, which is part of the series entitled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”, shows the linear seismic response of crossover piping installed in a seismically isolated plant. The crossover piping, supported by both isolated and non-isolated buildings, deforms with large relative displacement between the two buildings and the seismic response of the crossover piping is caused by two different seismic excitations from the buildings. A flexible and robust structure is needed for the high-pressure crossover piping. In this study, shaking tests on a 1/10 scale piping model and FEM analyses were performed to investigate the seismic response of the crossover piping which was excited and deformed by two different seismic motions under isolated and non-isolated conditions. Specifically, as linear response analysis of the crossover piping, modal time-history analysis and response spectrum analysis with multiple excitations were carried out and the applicability of the analyses was confirmed. Moreover, the seismic response of actual crossover piping was estimated and the feasibility was evaluated.

scholarly journals Investigation of PTMD System Affected by Parkfield Near-Field Earthquake

2017 ◽  
Vol 11 (4) ◽  
pp. 70 ◽  
Author(s):  
Ali Vatanshenas
Keyword(s):  
Near Field ◽  
Structural Response ◽  
Time History ◽  
Steel Structure ◽  
Roof Displacement ◽  
Base Shear ◽  
Maximum Acceleration ◽  
Existing Structures ◽  
History Analysis ◽  
Reduction Methods

Earthquake is considered as the main destructive and collapsing factor of structures in near-fault zones, so design new structures and retrofitting existing structures in order to decrease structural responses is an unavoidable matter. One of the structural response reduction methods is using of TMDs. In this paper, a two-dimensional 10-storey steel structure as three structural models without PTMD, with a PTMD at the highest level and ten PTMDs with different characteristics at all levels with the Modal-FNA time-history analysis method under acceleration records with directivity and without directivity of Parkfield 2004 earthquake at the angle of the maximum acceleration response in the first mode period of structure after rotating the acceleration records at the station with directivity and its corresponding angle at the station without directivity were compared to each other in terms of the roof displacement, the input energy and the base shear. It was observed that the structure behavior in the case of using only one PTMD is better, but in the case where ten PTMDs with relative smaller masses were used compared to the case where only one PTMD was used is also with roof displacement reduction.

scholarly journals Determining the Effect of Adding Greenhouse Structure to a Residential Building Using Friction Pendulum System (FPS) under Near-Field Earthquakes

2018 ◽  
Vol 8 (1) ◽  
pp. 56
Author(s):  
Ali Vatanshenas ◽  
Behnam Tavakoli Moghadam
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Residential Building ◽  
Roof Displacement ◽  
Base Shear ◽  
Additional Mass ◽  
Pendulum System ◽  
Rigid Connection ◽  
Friction Pendulum ◽  
Base Structure

Adding greenhouse structures to existing residential structures in order to increase agricultural products is considered as a challenge. In this paper the comparison of a three-dimensional residential building is investigated in three cases: without greenhouse structure, with rigid connection to the greenhouse structure and the greenhouse structure seismically isolated from the base structure using FPS. It was observed that adding additional mass on the last floor of the base structure can cause an unpredictable increase in the amounts of base shear and roof displacement. It was observed that FPS showed a proper behavior during near-field earthquakes. In terms of base shear and roof displacement the structure with FPS showed a better performance than the structure without FPS.

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