scholarly journals Multihazard Response Control of Base-Isolated Buildings under Bidirectional Dynamic Excitation

2020 ◽  
Vol 2020 ◽  
pp. 1-24
Author(s):  
Daniel H. Zelleke ◽  
Sandip K. Saha ◽  
Vasant A. Matsagar
Keyword(s):  
Design Parameters ◽  
Pendulum System ◽  
Multistory Buildings ◽  
Rubber Bearing ◽  
Building Models ◽  
Lead Rubber Bearing ◽  
Multistory Building ◽  
Fixed Base ◽  
Laminated Rubber Bearing ◽  
Isolation Systems

The issues of safety and posthazard functionality of structures under multihazard scenarios are some of the significant challenges in the current dynamic and rapidly growing urban environment. In this paper, multistory base-isolated buildings are investigated under the independent multihazard scenario of earthquake and blast-induced ground motion (BIGM). Multistory building models equipped with five different types of isolation systems, namely, the laminated rubber bearing (LRB), lead-rubber bearing (N-Z system), pure friction (PF) system, friction pendulum system (FPS), and resilient-friction base isolator (R-FBI) are assessed under bidirectional multihazard excitations. The suitability of the isolation systems and their key parameters in protecting multistory buildings is evaluated. Furthermore, the influence of the superstructure characteristics, such as the superstructure damping and the number of stories, is also assessed. The effect of bidirectional hazards on fixed-base buildings is also presented for comparison. The key response quantities of base-isolated buildings are presented and compared for different isolation systems. Parametric investigations are also conducted, and the trends of the response quantities are presented to study the influence of important parameters of isolation systems in protecting the buildings under the multihazard scenario of earthquake and BIGM. The results of the investigation show that the behaviors of the buildings equipped with various isolation systems are different for the two hazards. Moreover, the influences of the key parameters of the isolation systems are found to be different for various hazards. Therefore, the selection of design parameters of isolation systems shall be made with due consideration of the influence of multiple hazards. Additionally, the influence of the properties of the superstructure, such as the number of stories and the damping of the superstructure, on the behavior of the base-isolated buildings under the multihazard loading, is presented.

scholarly journals THE INVESTIGATION BASE ISOLATOR IN CONTROLLING THE RESPONSE OF THE STRUCTURES DURING EARTHQUAKES

2018 ◽  
Vol 1 (18) ◽  
Author(s):  
Barghlame Hadi ◽  
Gavgani Hojjat Hashempour
Keyword(s):  
Base Isolation ◽  
Comparative Investigation ◽  
Pendulum System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
High Damping Rubber ◽  
Isolation Systems ◽  
Friction Pendulum ◽  
Base Isolators

Base isolation systems are among the most successful and widely applied methods of mitigatingstructural vibration and damage during seismic events. These systems have been installed in numerousfull-scale structures all around. There are three principal types of base isolators: Lead Rubber Bearing(LRB), High Damping Rubber Bearing (HDRB), and Friction Pendulum System (FPS). It is necessaryto extensively examine the response of different LRB isolators—by combining them with re-centeringand damping properties for isolated steel frame buildings experiencing several NF ground motions. Thepresent research uses comparative-descriptive methodology and application in terms of objectives. Thedata needed for the study were collected using library references and through reviewing related studiesconducted in the past in the same field.Results of the current comparative investigation indicated significant reductions in the storey drift,shear, and acceleration and increment in the storey displacement. According to the findings of thecurrent study, base isolators provide flexibility to massive structures against earthquakes. Thesestructures are situated on rigid soils. Moreover, base isolation was found to be the most effective incontrolling the response of the structures during earthquakes. Finally, shear, storey drift, and storeydisplacement reduce due to the use of base isolators as compared to the fixed-base structure.

scholarly journals Effect of Building Height on Torsional Rotation of base Isolated Structures

2019 ◽  
Vol 8 (3) ◽  
pp. 1754-1760
Keyword(s):  
Pendulum System ◽  
Torsional Response ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Base Isolator ◽  
Fixed Base ◽  
Isolated Structures ◽  
Friction Pendulum ◽  
Torsional Rotation ◽  
Base Structure

The effect of height variation of a base isolated building on torsional response has been studied in the paper Also response of lead rubber and friction pendulum base isolator on torsional rotation has been compared. For the study, building rests on friction pendulum system (FPS) and lead rubber bearing (LRB) has been considered. The height of the building is varied successively and subjected to bi-directional seismic excitation. The torsional response of isolated structure is studied for each increment in the storey height for both LRB and FPS isolators and compared with fixed base structure. The result indicates that, base isolated structures reduces torsional rotation. It is also found that torsional rotation for buildings of ten to fifteen stores have significant reduction compared to other models considered in present study. Beyond this, the effectiveness reduces. It is also observed that FPS base isolator has effectively reduced torsional rotation when compared to LRB.

scholarly journals A comparative study of base isolation devices in light rail transit structure featured with lead rubber bearing and friction pendulum system

2018 ◽  
Vol 195 ◽  
pp. 02013
Author(s):  
Santi Nuraini ◽  
Asdam Tambusay ◽  
Priyo Suprobo
Keyword(s):  
Seismic Isolation ◽  
Time History ◽  
Light Rail ◽  
Rail Transit ◽  
Light Rail Transit ◽  
Pendulum System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Friction Pendulum ◽  
Friction Pendulum System

Advanced nonlinear analysis in light rail transit (LRT) structures has been undertaken to examine the influence of seismic isolation devices for reducing seismic demand. The study employed the use of two types of commercially available bearings, namely lead rubber bearing (LRB) and friction pendulum system (FPS). Six LRT structures, designed to be built in Surabaya, were modelled using computer-aided software SAP2000, where each of the three structures consisted of three types of LRB and FPS placed onto the pier cap to support the horizontal upper-structural member. Nonlinear static pushover and dynamic time history analysis with seven improved ground motion data was performed to gain improved insights on the behavioural response of LRT structures, allowing one to fully understand the supremacy of seismic isolations for protecting the structure against seismic actions. It is shown that both devices manage to isolate seismic forces, resulting in alleviation of excessive base shear occurring at the column. In addition, it is noticeable that the overall responses of LRB and FPS shows marginal discrepancies, suggesting both devices are interchangeable to be used for LRT-like structures.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 6 — Scaled Tests to Obtain Basic Characteristics of Lead Rubber Bearing

2014 ◽  
Author(s):  
Tsutomu Hirotani ◽  
Ryota Takahama ◽  
Masaki Yukawa ◽  
Hiroshi Hibino ◽  
Yuji Aikawa ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Loading Test ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Basic Characteristics ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Hysteresis Characteristics

This paper provides a series comprising the “Development of Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. Part 6 presents scaled tests for Lead Rubber Bearing (LRB) newly developed for this project. Following tests are performed to obtain the basic characteristics of LRB,. (1) Horizontal and Vertical Simultaneous Loading Test: LRBs with diameter of 250mm are tested dynamically under simultaneous axial and lateral loading. The hysteresis characteristics is not changed under compressive load although it is changed under tensile load. (2) Basic Break Test: LRBs with a diameter of 800mm are tested statically under various combinations of axial and lateral forces. The hysteresis characteristics model of LRB is determined by this test. It is confirmed that the breaking strain of LRB under compression load exceeds 450%. (3) Horizontal Hardening and Vertical Softening Test: For LRBs with a diameter of 1200 mm, 75% scale of actual LRB are tested statically for horizontal hardening and vertical softening regions. It is confirmed that the hysteresis model which is developed by smaller LRBs is applicable to these large scale models.

scholarly journals Improving the Seismic Behavior of Symmetrical Steel Structures Under Near-Field Earthquake Using a Base Isolation Method Lead Rubber Bearing Isolator

2016 ◽  
Vol 10 (7) ◽  
pp. 10
Author(s):  
Musa Mazji Till Abadi ◽  
Behnam Adhami
Keyword(s):  
Seismic Isolation ◽  
Retaining Wall ◽  
Vertical Component ◽  
Steel Structures ◽  
Vertical Movements ◽  
Near Fault ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
Near Fault Earthquakes

<p>In this study, the function and application of seismic isolation system through lead rubber bearing isolator (LRB) in near-fault earthquakes are compared with fixed-base structures. As a result of their high frequency content, near-fault earthquakes impose huge energy on structures and cause severe damages. One of the appropriate solutions for this issue is the use of LRB which decreases the amount of imposed energy on structures. To improve the function of isolated structures under the near-fault earthquakes, isolators are designed in a way to tolerate the vertical component of earthquakes. To this purpose, we limit the displacements due to the horizontal movements of isolator through Gap spring which acts as a retaining wall and prevent shocks to other buildings. Moreover, this approach decreases the vertical movements of isolators and indirectly improves their behavior. In the current study, three buildings with four, eight, and 12 floors (with and without gap spring) were included. Isolators were manually designed in accordance with AASHTO-LRB regulations and the behaviors of both isolators and buildings are considered non-linear. Then we analyzed and compared the amount of energy, displacement, and acceleration of structure at the center of roof. The results indicated a significant decrease in the results of base shear, the acceleration of roof center, floors drift and energy imposed on the structure in the isolated system in comparison with the fixed-base structure.</p>

Seismical Protection Properties of High Damping Rubber Bearing and Lead Rubber Bearing Base Isolation Systems for Multi-Storey RC Buildings

2012 ◽  
Vol 234 ◽  
pp. 90-95 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis
Keyword(s):  
Base Isolation ◽  
Response Spectrum ◽  
Limit State ◽  
Three Dimensional ◽  
Elastic Response ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
High Damping Rubber Bearing ◽  
High Damping Rubber ◽  
Isolation Systems

In the present paper two different base isolation systems, designed and verified according to the european seismic code (EC2 and EC8), are compared for evaluating the behaviour of a base isolated building, highly irregular in plan, in presence of a seismic excitation. The devices adopted for realizing the different base isolation systems are the High Damping Rubber Bearing (HDRB) and the Lead Rubber Bearing (LRB) both of them actuated in parallel with a Friction Slider (FS). A dynamic nonlinear analysis for a three-dimensional base isolated structure has been performed. Recorded accelerograms for bi-directional ground motions, compatible with the reference elastic response spectrum for each limit state have been used for a more realistic evaluation of the seismic response of the structure and a more realistic comparative analysis between the base isolated structure with the different considered base isolation systems and the traditional fixed base structure.

scholarly journals Effects of Shape Memory Alloys on Response of Steel Structural Buildings within Near Field Earthquakes Zone

2020 ◽  
Vol 6 (7) ◽  
pp. 1314-1327
Author(s):  
Mahmoud Ahmadinejad ◽  
Alireza Jafarisirizi ◽  
Reza Rahgozar
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Base Isolation ◽  
Near Field ◽  
Seismic Zone ◽  
Isolation System ◽  
Residual Displacements ◽  
Rubber Bearing ◽  
Laminated Rubber Bearing ◽  
Isolation Systems

Base isolation is one of the effective ways for controlling civil engineering structures in seismic zone which can reduce seismic demand. Also is an efficient passive control mechanism that protects its superstructure during an earthquake. However, residual displacement of base-isolation systems, resulting from strong ground motions, remain as the main obstacle in such system’s serviceability after the earthquake. Shape Memory Alloys (SMA) is amongst the newly introduced smart materials that can undergo large nonlinear deformations with considerable dissipation of energy without having any permanent displacement afterward. This property of SMA may be utilized for designing of base isolation system to increase the structure’s serviceability. Here, a proposed semi-active isolation system combines laminated rubber bearing system with shape memory alloy, to take advantage of SMAs high elastic strain range, in order to reduce residual displacements of the laminated rubber bearing. Merits of the system are demonstrated by comparing it to common laminated rubber bearing isolation systems. It is found that the optimal application of SMAs in base-isolation systems can significantly reduce bearings’ residual displacements. In this study, OpenSees program for a three dimensional six-storey steel frame building has been used by locating the isolators under the columns for investigating the feasibility of smart base isolation systems, i.e., the combination of traditional Laminated Rubber Bearing (LRB) with the SMA, in reducing the structure’s isolated-base response to near field earthquake records are examined. Also, a new configuration of SMAs in conjunction with LRB is considered which make the system easier to operate and maintain.

Experimental Study on Three-Dimensional Base-Isolated Model with 3DIB

2011 ◽  
Vol 255-260 ◽  
pp. 2325-2329
Author(s):  
Ya Min Zhao ◽  
Jing Yu Su ◽  
Ming Lu
Keyword(s):  
Three Dimensional ◽  
Shaking Table ◽  
Vertical Acceleration ◽  
Shaking Table Tests ◽  
3 Dimensional ◽  
Horizontal Acceleration ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Disk Spring ◽  
Fixed Base

A new 3-dimensional isolation bearing (3DIB), which is combined with lead rubber bearing (LRB) and disk spring bearing (DSB), is introduced in this paper. A series of shaking table tests of the 1/2 scale fixed-base and 3DIB base-isolated model were compared to confirm the validity of the 3DIB. Results show that the 3DIB can isolate 3-dimensional earthquake energy remarkably. Large displacement of the 3DIB base-isolated system occurred on the isolation layer, and the inter-story deformation of the superstructure changed slightly. The horizontal acceleration responses of 3DIB model decreased more than 60% and the vertical acceleration responses decreased more than 50% under the severe earthquake of 0.4g in PGA input, which confirmed that 3DIB could isolate both the horizontal and vertical earthquakes obviously.

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.

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