scholarly journals Inelastic demand spectra for bi-linear seismic isolation systems based on nonlinear time history analyses and the response of lead-rubber bearing isolation systems subjected to near-source ground motions

2007 ◽  
Vol 40 (1) ◽  
pp. 7-17 ◽  
Author(s):  
John X. Zhao ◽  
Jian Zhang
Keyword(s):  
Seismic Isolation ◽  
Ground Motions ◽  
Time History ◽  
Design Tool ◽  
Nonlinear Time History Analysis ◽  
Inelastic Demand ◽  
Isolated Structures ◽  
Seismically Isolated ◽  
Isolation Systems ◽  
Nonlinear Time History

In this study, we present an inelastic demand spectrum for the design of seismically-isolated structures using lead-rubber bearings or other types of isolators with bi-linear hysteresis loops and the inelastic spectrum can be used in the design of seismically-isolated structures in a very similar manner to capacity spectrum method. The inelastic demand spectrum is a very useful design tool for visual selection of optimal isolation parameters, and eliminates the use of equivalent linear-elastic substitute structures as the displacement demand is obtained from nonlinear time history analysis. The responses of seismically-isolated structures subjected to near-source ground motions with either large forward-directivity pulses or fault-fling pulses are presented. Our analyses suggest that seismic isolation can be used to protect structures subjected to recorded ground motions currently available to us, with acceptable levels of base shear coefficient and isolator displacement, except for one component of the TCU068 record from the 1999 Chichi, Taiwan, earthquake (which contained a large permanent displacement of nearly 10 m).

scholarly journals The Next Generation of Seismic Isolation Going Beyond Seismic Design Dominated by Earthquakes

2008 ◽  
Vol 3 (6) ◽  
pp. 479-502 ◽  
Author(s):  
Mitsuo Miyazaki ◽  
Keyword(s):  
Dynamic Response ◽  
Seismic Isolation ◽  
Ground Motions ◽  
Elastic Strain Energy ◽  
Intensity Level ◽  
Next Generation ◽  
Earthquake Intensity ◽  
Isolated Structures ◽  
Seismically Isolated ◽  
Isolation Systems

Seismic isolation can provide superior building safety and dynamic response during strong earthquakes, however, performance is only assured below the design earthquake intensity level. This paper opens with a study of observed strong, near-source ground motions and long-period earthquake waves proposed by researchers. Through the examination of a widerange of earthquake response and input energy spectra, up to a period of 100 seconds, the most suitable range of damping values and isolation periods are found. The optimal period range is further confirmed by evaluating earthquake-wave amplification features during propagation from bedrock to the ground surface. Three types of next-generation seismic isolation systems are proposed along with new parameters to evaluate the dynamic response of seismically isolated structures. By comparing the dynamic response performance of four isolation systems, including a "conventional" 4-second period system, the superior seismic performance of the three next-generation isolation systems is confirmed. The paper shows the direction for a new generation of seismically isolated structures, with periods exceeding 10 seconds, and which minimize the elastic strain energy stored in the structure. Seismically isolated structures possessing these properties will survive strong earthquake input regardless of the uncertainty inherent in earthquake ground motions.

Seismic Isolation Retrofit of an Office Building Using Friction Pendulum System

2014 ◽  
Vol 578-579 ◽  
pp. 1361-1365
Author(s):  
Lin Liu ◽  
Xuan Min Li ◽  
Wei Tian
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Nonlinear Behavior ◽  
Office Building ◽  
Nonlinear Time History Analysis ◽  
Isolation System ◽  
Pendulum System ◽  
Nonlinear Time History ◽  
Friction Pendulum

Friction Pendulum Systems have been used as base isolation systems for both new construction and retrofit around the world. This paper presented its implementation in an office building located in Shanghai. To evaluate its impact on seismic performance of the retrofitted structure, models are needed to capture the intricate nonlinear behavior of both structural components and isolator elements. Nonlinear time history analysis of the building for the original and retrofitted cases was conducted to assess the efficiency of the isolation system at the high earthquake level. The numerical results indicate that the retrofitted structure experiences significantly less damage and less deformation due to the shake isolation and energy dissipation through the isolators.

scholarly journals Isolating system using U Shaped steel damper

2021 ◽  
Vol 309 ◽  
pp. 01136
Author(s):  
Siripuram Vamshisheela ◽  
Atulkumar Manchalwar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Base Shear ◽  
Energy Device ◽  
History Analysis ◽  
Structural Responses ◽  
Nonlinear Time History ◽  
Story Building

In this work the performance of U-Shaped Steel Isolator is evaluated for a 5-story building subjected to seismic and blast vibrations. The structure is analysed using SAP 2000 software and a nonlinear time history analysis is carried out. The effectiveness of using base isolation is studied by comparing the structural responses of the building with isolator and without isolator and noticeable difference was observed. As the U-Shaped isolator absorbs the energy in all directions, it effectively controls the structural responses. In this study, the building is subjected to four different seismic and four different blast induced ground motions. It was observed that by the use of supplementary energy device there is reduction in top story acceleration, base shear and less deformation in the structure. This study concludes that the use of isolator has been effective in minimizing structural responses.

scholarly journals Seismic Design of Bridges against Near-Fault Ground Motions Using Combined Seismic Isolation and Restraining Systems of LRBs and CDRs

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Xiaoli Li ◽  
Yan Shi
Keyword(s):  
Control System ◽  
Seismic Design ◽  
High Intensity ◽  
Seismic Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Near Fault ◽  
Combined Control ◽  
Quantitative Design

This paper focuses on the seismic isolation design of near-fault bridges under the seismic excitations of near-fault ground motions in high-intensity earthquake zones and proposes a combined control system using lead rubber bearings (LRBs) and cable displacement restrainers (CDRs) along with ductility seismic resistance for the reinforced concrete piers. As part of the performance-based seismic design framework, this study provides the quantitative design criteria for multilevel performance-based objectives of a combined control system under conditions of frequent earthquake (E1), design earthquake (medium earthquake), and rare earthquake (E2). Moreover, in this study, a preliminary performance-based seismic isolation design for a near-fault actual highway bridge in high-intensity earthquake zones (basic peak of ground acceleration 0.4 g) was developed. Using nonlinear time-history analysis of the actual bridge under near-fault ground motions, the feasibility of a performance-based design method was validated. Furthermore, to ensure the predicted performance of the isolated bridges during a strong earthquake, a relatively quantitative design in structural details derived from the stirrup ratio of piers, expansion joints gap, supported length of capping beams, and limited vertical displacement response was obtained.

scholarly journals Improvements to the simplified analysis method for the design of seismically isolated bridges in CSA-S6-14

2016 ◽  
Vol 43 (10) ◽  
pp. 897-907
Author(s):  
Viacheslav Koval ◽  
Constantin Christopoulos ◽  
Robert Tremblay
Keyword(s):  
North America ◽  
Seismic Isolation ◽  
Time History ◽  
Equivalent Damping ◽  
Damping Coefficients ◽  
Simplified Method ◽  
Simplified Analysis ◽  
Seismically Isolated ◽  
Nonlinear Time History ◽  
Isolated Bridges

The design provisions for seismically isolated bridges in the CAN/CSA-S6 Canadian Highway Bridge Design Code and the AASHTO Guide Specifications for Seismic Isolation Design ( AASHTO 2010 , 2014 ) have been developed primarily based on ground motions recorded along the west coast of North America. Both codes include a simplified analysis procedure that relies on an equivalent effective linearization of the nonlinear isolated structure together with damping coefficients to account for the effect of energy dissipation on the response of the isolated system. The appropriateness and range of application of code-specified simplified methods were investigated through nonlinear time-history analyses to propose improvements to this procedure for the new edition of the CSA-S6-2014 code. Based on these analyses, new damping coefficients are proposed for Eastern North America (ENA) and new limits for the application of the simplified method are defined. For ENA, the method with newly proposed damping coefficients can give good bridge displacement estimates for equivalent damping ratios of up to 40%, which broadens the possible designs that can be achieved using the simplified method. This study also showed that applicability limits could be defined more accurately as a function of the system properties.

HHT-BASED SIMULATION OF UNIFORM HAZARD GROUND MOTIONS

2009 ◽  
Vol 01 (01) ◽  
pp. 71-87 ◽  
Author(s):  
Y. K. WEN ◽  
PING GU
Keyword(s):  
Los Angeles ◽  
Ground Motions ◽  
Time History ◽  
Simulation Method ◽  
Nonlinear Time History Analysis ◽  
Rupture Directivity ◽  
Regional Seismicity ◽  
Hilbert Huang Transform ◽  
History Analysis ◽  
Nonlinear Time History

Hilbert–Huang Transform (HHT) is a new analysis method for nonstationary and nonlinear signals. A simulation method based on HHT is used to generate uniform hazard ground motions, which are often needed for nonlinear time history analysis for structures in high-seismic zones. The HHT-based simulation method can reproduce the amplitude and frequency content change with time for nonstationary random processes, thus is very suitable for the simulation of earthquake ground motions, especially the near-fault ground motions with long-period pulses. Monte-Carlo method and historical earthquake records are used for the generation of a large pool of ground motions, from which the uniform hazard ground motions are selected. The regional seismicity and rupture directivity are considered. An example is given of a site near Los Angeles City Hall. The advantages and difficulties of the proposed method are also discussed.

Seismic Isolation Design of Multistory Building

2012 ◽  
Vol 204-208 ◽  
pp. 3592-3595
Author(s):  
Xiao Song ◽  
Peng Li ◽  
Guang Sheng Xu
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Seismic Capacity ◽  
Isolation System ◽  
Multistory Building ◽  
History Analysis ◽  
Base Isolation System ◽  
Nonlinear Time History

Design process and the nonlinear time history analysis for base isolation system is performed in this paper. The results show that the earthquake acceleration and displacement response of isolated structure can be significantly reduced. Application of the isolation system to improve the seismic capacity of the structure,can effectively reduce the response of upper structure of in earthquake.

scholarly journals Response control of structures under Seismic and Blast induced ground motions

2021 ◽  
Vol 309 ◽  
pp. 01137
Author(s):  
Vamshisheela Siripuram ◽  
Atulkumar Manchalwar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Base Shear ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
Isolation Device ◽  
Nonlinear Time History

In the present paper an investigation is carried out to evaluate the efficiency of Base Isolation device in a building subjected to both seismic and blast induced ground motions. A 5-story building is modelled with different story stiffness and floor masses is considered in this study. In SAP 2000 software two buildings, one with fixed base and the other with isolated base are designed and nonlinear time history analysis is conducted. The structural responses of these two models subjected to four recorded earthquakes and four different blast ground accelerations is compared in this study. The base isolated device such as lead/rubber bearing have proved to be effective in reducing the base Shear and Top story acceleration, and also increase in Hysteresis energy in the base isolated structure subjected to seismic and blast vibrations.

scholarly journals Comparison and analysis of seismic isolation, energy dissipation structure and traditional seismic structure

2021 ◽  
Vol 248 ◽  
pp. 01001
Author(s):  
Shu-jiang Jiang ◽  
Shun-zhong Yao ◽  
De-wen Liu
Keyword(s):  
Seismic Isolation ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Seismic Structure ◽  
Base Shear ◽  
Finite Element Software ◽  
History Analysis ◽  
Rare Earthquake ◽  
Nonlinear Time History ◽  
The Impact

This paper uses SAP2000 finite element software to perform nonlinear time history analysis of nine structural systems, and compares the period, total floor displacement, base shear force, vertex displacement, and top acceleration of the structure under the action of an 8-degree rare earthquake. The research results show that seismic isolation and damping technology can effectively reduce the impact of earthquakes on structures.

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