Optimization of Yield Shear Coefficient for Parallel Base Isolation System

2012 ◽  
Vol 166-169 ◽  
pp. 363-366
Author(s):  
Qiang Rong ◽  
Yan Sheng
Keyword(s):  
Objective Function ◽  
Seismic Waves ◽  
Base Isolation ◽  
Energy Scale ◽  
Scale Factor ◽  
Base Shear ◽  
Optimal Range ◽  
Isolation System ◽  
Shear Coefficient ◽  
Base Isolation System

The optimization of yield shear coefficient for parallel base isolation system is investigated systematically. The maximum dissipative energy scale factor is used as the objective function, the maximum sliding displacement of a base-isolated layer, the residual displacement and the maximum base shear coefficient are considered the constraining factors. The optimal range of the yield shear coefficient is proposed by inputting the seismic waves of the different sites.

Optimization of Second Isolation Period for Parallel Base-Isolated System

2012 ◽  
Vol 256-259 ◽  
pp. 1117-1120
Author(s):  
Q. Rong
Keyword(s):  
Objective Function ◽  
Seismic Response ◽  
Base Isolation ◽  
Energy Scale ◽  
Base Shear ◽  
Isolation System ◽  
Base Isolation System ◽  
Low Amplitude ◽  
Variation Rule ◽  
Isolation Period

The optimization of second isolation period for parallel base isolation system is investigated systematically. The maximum dissipative energy scale factor is used as the objective function, the maximum sliding displacement of base-isolated layer, the residual displacement and the maximum base shear coefficient are considered as the constraining factors. For first to fourth category site, under the low amplitude severe earthquake, the variation rule of the four seismic response indicators for the second isolation period is approximately same, the second isolation period is proposed to be in the range of 4s to 6s.

scholarly journals Influence at Mass of the Base Isolation System in Affecting the Higher Modes of Vibration

2021 ◽  
Vol 12 (2) ◽  
pp. 1809-1815
Author(s):  
Cici Jennifer Raj J, Et. al.
Keyword(s):  
Seismic Waves ◽  
Base Isolation ◽  
Mode Shapes ◽  
Isolation System ◽  
Higher Modes ◽  
Remarkable Effect ◽  
Base Isolator ◽  
Key Factor ◽  
Modes Of Vibration ◽  
Base Isolation System

Base Isolation is a technology of mitigating the effects due to earthquakes with the aspect of dissipating the seismic waves away from the superstructure, by isolating the superstructure from the ground.This concept is widely essential to be implemented in structures(buildings) irrespective of many factors. There are several materials which could be implemented as base isolator, however the need in reduction of the number of the isolators is essential dueto various factors which a developing country finds difficult to implement. In this paper, a three-storey unsymmetrical building to be considered for the study is isolated by varying the mass of the foundation beam, (Transfer beam) thereby reducing the number of isolators in the building.Furthermore,the mode shapes and  frequencies of the structure without base isolation and with base isolation considering mass of the base isolation system as a key factor were analysed and compared and hence the variation in the mass of the isolation system has a promising effect in altering the higher modes of vibration. The analysis is prolonged using  another methd using UBC-1997 provisions and compared. In both the methods, the influence of the mass of the isolation system has a remarkable effect in altering the higher modes of vibration.

Seismic Evaluation of Base Isolated System Equipped with Shape Memory Alloys

2013 ◽  
Vol 831 ◽  
pp. 110-114
Author(s):  
S. Alvandi ◽  
M. Ghassemieh
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Seismic Isolation ◽  
Passive Control ◽  
Structural Model ◽  
Base Isolation ◽  
Base Shear ◽  
Seismic Evaluation ◽  
Isolation System ◽  
Base Isolation System

Seismic isolation system is an example of passive control system that effectively improves the performance of structures. This research discusses the seismic performance of a elastomeric base isolation system which provide the combined features of vertical load support, horizontal flexibility and energy absorbing capacity, utilizing shape memory alloys that provides re-centering force and additional damping in the system. Also this paper compares the effect of such alloys with memory effect and/or superelasticity (with pre-straining) in base isolated structure. To provide such comparison, a nonlinear structural model has been developed on some benchmark control problems and some health monitoring evaluation criterias are used. The smart base isolation utilizes the different responses of shape memory alloys at several levels of strain to control the displacements of the rubber bearing and base shear at excitation level. Furthermore the proposed based isolation systems has enhanced performance in terms of response reduction and re-centering capacity.

scholarly journals Seismic Performances of Conventional and LRB-Isolated Buildings Comparing to Seesaw Buildings

2020 ◽  
Vol 10 (1) ◽  
pp. 45-54
Author(s):  
Soroush Kherad ◽  
Mahmood Hosseini ◽  
Mehrtash Motamedi
Keyword(s):  
Base Isolation ◽  
Low Cost ◽  
Time History ◽  
Building Structure ◽  
Base Shear ◽  
Isolation System ◽  
Repair Work ◽  
Story Drift ◽  
Base Isolation System ◽  
Nonlinear Time History

AbstractUsing seesaw structural system equipped with energy dissipating devices has been considered as a low-cost and low-tech way for creation of earthquake-resilient buildings. In this paper by considering three groups of multi-story buildings, including conventional buildings, LRB-based isolated buildings and building with seesaw structure, equipped with a newly introduced type of structural fuses, their seismic performances have been compared through nonlinear time history analyses (NLTHA). The employed fuses in seesaw buildings are a specific type of yielding plate dampers, called Multiple Curved Yielding Plate Energy Dissipater (MCYPED), installed at the bottom of the all circumferential columns of the lowest story of the building. To show the efficiency of the proposed seesaw system in comparison with other two mentioned groups, first, by finite element modeling, verified by experimental results, the initial and secondary stiffness values as well as the yielding and ultimate strengths of the MCYPEDs have been obtained to be modeled by multi-linear plastic springs in the seesaw buildings. Then, a series of NLTHA have been performed on the three groups of buildings by using a set of selected earthquakes. The compared responses include roof displacement and acceleration, base shear, inter-story drift and finally plastic hinges (PHs) formed in the building’s structures. Results show that the proposed seesaw building equipped with MCYPEDs not only results in lower seismic demand, similar to base isolation system, but also leads to remarkable energy dissipation capacity in the building structure at base level, so that the building structure remains basically elastic, and does not need any major repair work, even after large earthquakes, contrary to the conventional building which need to be demolished after the earthquake.

scholarly journals Seismic Vibration Control of Building with Lead Rubber Bearing Isolator

10.29007/pvzx ◽  
2018 ◽  
Author(s):  
Kishan Bhojani ◽  
Vishal Patel ◽  
Snehal Mevada
Keyword(s):  
Seismic Response ◽  
Base Isolation ◽  
Time History ◽  
Dynamic Parameter ◽  
Base Shear ◽  
Maximum Displacement ◽  
Maximum Acceleration ◽  
Isolation System ◽  
Loma Prieta Earthquake ◽  
Base Isolation System

During the life span of structure there may be an effect of vibration. Due to vibration there may be major or minor damage in building. Base isolation is best method to reduce the seismic response of the structure. This paper gives idea about base isolation system which can be used in multi-story building to reduce seismic response of the structure. This paper represents the initialize study of dynamic parameter like effective damping for four earthquake time history. In this paper the optimum effective damping has been found out under the effect of Loma Prieta earthquake time history. The parametric study has been conducted to evaluate the effect on maximum displacement, maximum acceleration, maximum base shear in bare frame and frame with isolator.

scholarly journals Analytical and Experimental Overview of Fiber Reinforced Elastomeric Isolator

2021 ◽  
Vol 9 (VII) ◽  
pp. 3906-3911
Author(s):  
Afroz Qureshi
Keyword(s):  
Seismic Isolation ◽  
Seismic Waves ◽  
Base Isolation ◽  
Low Cost ◽  
Fiber Reinforced ◽  
Effective Response ◽  
Isolation System ◽  
Vertical Stiffness ◽  
Base Isolation System ◽  
Fiber Reinforced Elastomeric Isolator

There has been many researches in order to further improve the Base Isolation system by trying various combinations and alternative materials. In that fiber reinforced isometric isolators are emerged as a viable solution, because for the low cost and effective response to seismic waves as compared to the conventional isolators. Studies further shows that it provides high vertical stiffness and low horizontal stiffness, also having effective damping over the conventional one. Developing countries who doesn’t have proper seismic protection solutions have found this convenient as they are comparatively less in cost and doesn’t require complex installation. Studies also shows Un-bonded FREI has lower horizontal stiffness and considerably lower stress demand on rubber material as compared to the B-FREI and hence significantly higher seismic isolation efficiency.

scholarly journals Seismic Response Analysis of Fully Base-Isolated Adjacent Buildings with Segregated Foundations

2018 ◽  
Vol 2018 ◽  
pp. 1-21 ◽  
Author(s):  
Khaled Ghaedi ◽  
Zainah Ibrahim ◽  
Mohammed Jameel ◽  
Ahad Javanmardi ◽  
Hamed Khatibi
Keyword(s):  
Base Isolation ◽  
Separation Distance ◽  
Response Analysis ◽  
Seismic Gap ◽  
Base Shear ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Adjacent Buildings ◽  
Construction Methods ◽  
Base Isolation System

In populous cities, construction of multistorey buildings close to each other due to space limitation and increased land cost is a dire need. Such construction methods arise several problems during earthquake excitation. The aim of this study is to investigate the bidirectional seismic responses of fully base-isolated (FBI) adjacent buildings having different heights and segregated foundations. Therefore, two scenarios, namely, (a) investigation of the responses of FBI adjacent buildings compared to those with fixed base (FFB) and (b) the effects of separation distance on FBI adjacent buildings, were studied. Based on these investigations, the results showed that isolation system significantly enhances the overall responses of the BI buildings. Spectacularly, the base isolation system was further efficient to decrease displacement rather than the acceleration. In addition, increase of the seismic gap changed the acceleration, pounding, base shear, base moment, and storey drift, as well as the force-deformation performance of the isolators. Therefore, it seems a need to focus on the effect of the separation distances for the design of base isolators for FBI adjacent buildings in future works.

scholarly journals Influence of Elastomeric Bearings in Tension on the Seismic Performance of Base-Isolated r.c. Buildings

2020 ◽  
Vol 11 (1) ◽  
pp. 82
Author(s):  
Fabio Mazza ◽  
Mirko Mazza
Keyword(s):  
Base Isolation ◽  
Nonlinear Models ◽  
Vertical Component ◽  
Computer Code ◽  
Nonlinear Phenomena ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Near Fault ◽  
Base Isolation System ◽  
Near Fault Earthquakes

Elastomeric bearings are commonly used in base-isolation systems to protect the structures from earthquake damages. Their design is usually developed by using nonlinear models where only the effects of shear and compressive loads are considered, but uncertainties still remain about consequences of the tensile loads produced by severe earthquakes like the near-fault ones. The present work aims to highlight the relapses of tension on the response of bearings and superstructure. To this end, three-, seven- and ten-storey r.c. framed buildings are designed in line with the current Italian seismic code, with a base-isolation system constituted of High-Damping-Rubber Bearings (HDRBs) designed for three values of the ratio between the vertical and horizontal stiffnesses. Experimental and analytical results available in literature are used to propose a unified nonlinear model of the HDRBs, including cavitation and post-cavitation of the elastomer. Nonlinear incremental dynamic analyses of the test structures are carried out using a homemade computer code, where other models of HDRBs considering only some nonlinear phenomena are implemented. Near-fault earthquakes with comparable horizontal and vertical components, prevailing horizontal component and prevailing vertical component are considered as seismic input. Numerical results highlight that a precautionary estimation of response parameters of the HDRBs is attained referring to the proposed model, while its effects on the nonlinear response of the superstructure are less conservative.

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