A Theoretical Study on Piezoelectric Smart Isolation System for Seismic Protection of Equipment in Near-fault Areas

2008 ◽  
Vol 20 (2) ◽  
pp. 217-232 ◽  
Author(s):  
Lyan-Ywan Lu ◽  
Ging-Long Lin
Keyword(s):  
Theoretical Study ◽  
Seismic Protection ◽  
Isolation System ◽  
Near Fault

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.

Performance of bi-directional elliptical rolling rods for base isolation of buildings under near-fault earthquakes

2017 ◽  
Vol 21 (5) ◽  
pp. 675-693 ◽  
Author(s):  
Aruna Rawat ◽  
Naseef Ummer ◽  
Vasant Matsagar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Frictional Resistance ◽  
Curved Surface ◽  
Isolation System ◽  
Near Fault ◽  
Earthquake Ground Motions ◽  
Base Isolation System ◽  
Near Fault Earthquakes ◽  
Storey Building

Rolling base isolation system provides effective isolation to the structures from seismic base excitations by virtue of its low frictional resistance. Herein, dynamic analysis of flexible-shear type multi-storey building mounted on orthogonally placed elliptical rolling rod base isolation systems subjected to bi-directional components of near-fault earthquake ground motions is presented. The orthogonally placed rods would make it possible to resist the earthquake forces induced in the structure in both the horizontal directions. The curved surface of these elliptical rods has a self-restoring capability due to which the magnitude of peak isolator displacement and residual displacement is reduced. The roughness of the tempered curved surface of the rollers dissipates energy in motion due to frictional damping. The seismic performance of the multi-storey building mounted on the elliptical rolling rod base isolation system is compared with that mounted on the sliding pure-friction and cylindrical rolling rod systems. Parametric studies are conducted to examine the behavior of the building for different superstructure flexibilities, eccentricities of the elliptical rod, and coefficients of friction. It is concluded that the elliptical rolling rod base isolation system is effective in mitigation of damaging effects of the near-fault earthquake ground motions in the multi-storey buildings. Even under the near-fault earthquake ground motions, the base-isolated building mounted on the elliptical rolling rods shows considerable reduction in seismic response. The isolator displacement with the elliptical rolling rod base isolation system is less in comparison to the pure-friction and cylindrical rolling rod systems.

Multi-level SMA/lead rubber bearing isolation system for seismic protection of bridges

2020 ◽  
Vol 29 (5) ◽  
pp. 055045 ◽  
Author(s):  
Sasa Cao ◽  
Osman E Ozbulut ◽  
Suiwen Wu ◽  
Zhuo Sun ◽  
Jiangdong Deng
Keyword(s):  
Seismic Protection ◽  
Isolation System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Multi Level

Vertical Vibration Control of Series Isolation System under Near-Fault Earthquake

2014 ◽  
Vol 638-640 ◽  
pp. 1952-1955
Author(s):  
Q. Rong ◽  
Yan Sheng ◽  
Shi Xin Liu
Keyword(s):  
Seismic Waves ◽  
Damping Ratio ◽  
Vertical Vibration ◽  
Isolation Effect ◽  
Earthquake Intensity ◽  
Isolation System ◽  
Vertical Stiffness ◽  
Isolation Layer ◽  
Near Fault ◽  
Composite Disk

Series isolation system consists of rubber isolation bearings and composite disk springs, determination method of vertical stiffness and vertical damping of isolation layer is given. Entering the near-fault vertical seismic waves, the affect of isolation layer parameters and earthquake intensity on the isolation effect is studied. Studies have shown that the vertical isolation effect increases with the increase of vertical damping ratio. When the damping ratio reaches a certain value, the isolated effect leveles off. When calculating model is adopted as the hierarchical model, vertical isolation effect has nothing to do with the increases of earthquake intensity.

scholarly journals Fuzzy Control for Seismic Protection of Semiactive Base-Isolated Structures Subjected to Near-Fault Earthquakes

2015 ◽  
Vol 2015 ◽  
pp. 1-17 ◽  
Author(s):  
Dahai Zhao ◽  
Yongxing Li
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Fuzzy Controller ◽  
Seismic Protection ◽  
Friction Damper ◽  
Design Spectrum ◽  
Near Fault ◽  
Isolated Structures ◽  
Near Fault Earthquakes ◽  
Elastic Design

This paper proposes a new fuzzy logic controller, which is designed for seismic protection of base-isolated structures utilizing piezoelectric friction damper against near-fault earthquakes for different ground sites. According to the elastic design spectrum that Eurocode 8 recommends, one 5% damped elastic design spectrum for Chi-Chi earthquake is proposed to generate artificial earthquakes of different ground sites. The proposed controller employs a hierarchic fuzzy control algorithm, in which a supervisory fuzzy controller governs a sublevel fuzzy controller by altering its input normalization factors according to current level of ground motion. In order to simultaneously reduce the base displacement and superstructure responses of the base-isolated structure during seismic excitations, genetic algorithm is employed to optimize the supervisory fuzzy controller and the preload of piezoelectric friction damper. The efficiency of the proposed controller is also compared with passive controller and a linear quadratic Gauss optimal controller. Numerical results show that the proposed fuzzy logic controller has favorable performance in mitigating the responses of the base-isolated structure.

Parametric study of stochastic seismic responses of base-isolated liquid storage tanks under near-fault and far-fault ground motions

2016 ◽  
Vol 24 (24) ◽  
pp. 5747-5764 ◽  
Author(s):  
Sina Safari ◽  
Reza Tarinejad
Keyword(s):  
Base Isolation ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Characteristic Parameter ◽  
Statistical Linearization ◽  
Storage Tanks ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Near Fault ◽  
Liquid Storage

Seismic response of base isolated steel liquid storage tanks is investigated in this study by a stochastic approach in frequency domain. For the purpose of evaluating different frequency contents of seismic events on the responses of fixed and isolated tanks, the earthquake excitation is characterized by power spectral density function. Since earthquake is a random process, stochastic seismic analysis is used and root mean square response predicts behavior of system properly. Two types of isolation system are assumed and nonlinear behavior of base isolation systems are developed by an iterative statistical linearization scheme. The study demonstrates the influence of each characteristic parameter of the storage tanks and isolation system and also excitation features. It is confirmed that near-fault earthquake excitations amplify the overall response of the system. Base isolation is known as an effective technique to reduce responses appropriately. It is demonstrated that the sloshing responses of the tanks is significantly reduced by sliding bearing. Further, excitation parameters, PGV/PGA ratio of records and pulse period in near-fault ground motions, that represent differences in two sets of earthquakes are defined to recognize variation of responses.

Seismic Performance of Guideway Sliding Isolator with Gap Springs for Precision Machinery

2008 ◽  
Vol 11 (5) ◽  
pp. 511-524
Author(s):  
George C. Yao ◽  
Wen-Chun Huang ◽  
Fan-Ru Lin
Keyword(s):  
Shaking Table Test ◽  
Model Simulation ◽  
Shaking Table ◽  
Viscous Damping ◽  
Far Field ◽  
Seismic Excitations ◽  
Isolation System ◽  
Near Fault ◽  
Seismic Motion ◽  
Nonlinear Performance

The performance of gap springs in a guideway sliding isolator (GSI) system developed to protect precision machinery against seismic motion has been studied. A spring is initially distanced from the system by a gap, causing the isolation system to exhibit nonlinear performance once the gap is closed, reducing the chance of resonance. A full-scale shaking table test of a 22-ton specimen and a numerical model simulation in SAP2000 have been performed. The study shows that springs possessing the appropriate gaps are more effective in controlling relative displacements than is a pure friction system. The optimal gap for a system subjected to far-field earthquakes was found to be 5mm. In addition, supplemental viscous damping of less than 15% of the critical damping had no significant effect on the GSI system far-field seismic response, but it did reduce the relative displacements of the system for near-fault seismic excitations.

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