Seismic analysis of large span spatial steel frame with isolation system

In the present paper the dynamic nonlinear analysis for a 3D base isolated structure is illustrated. A base isolated reinforced concrete building is designed and verified according to the European seismic codes such that the superstructure remains almost completely elastic and the nonlinear elements are localized only in the base isolation system. Nonlinear hysteretic models have been adopted to reproduce the cyclic behavior of the isolators. Two different base isolation systems are considered and their performances are compared for evaluating the behaviour of a base isolated building, highly irregular in plan, in presence of a seismic excitation defined with recorded accelerograms which characterize the bi-directional ground motions. The isolation system has been realized with a combination in parallel of elastomeric bearings and sliding devices. In the first analyzed isolation system we have used the High Damping Rubber Bearings (HDRB) and in the second analyzed isolation system we have used the Lead Rubber Bearings (LRB). Finally a comparative analysis between the base isolated structure with hybrid base isolation systems and the conventional fixed base structure is detailed.

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

Journal of Vibration and Control ◽

10.1177/1077546316647576 ◽

2016 ◽

Vol 24 (24) ◽

pp. 5747-5764 ◽

Cited By ~ 1

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.

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Vertical Motion Inputs for Seismic Analysis of Large Span Bridge

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.275-277.1403 ◽

2013 ◽

Vol 275-277 ◽

pp. 1403-1406

Author(s):

Zheng Ru Tao ◽

Xia Xin Tao

Keyword(s):

Seismic Analysis ◽

Three Dimensional ◽

Low Frequency ◽

Vertical Motion ◽

Vertical Acceleration ◽

Motion Field ◽

Large Span ◽

Acceleration Time Histories ◽

Time Histories ◽

Main Girder

In seismic analysis of large span bridge, inconsistent ground motions in three directions, lengthwise, lateral and vertical are required to input at the base of each of the two main girder piers. In order to adopt synthesized motion field for the inputs, a simple way to prepare the vertical motion is introduced for improvisation at this moment in this paper, since the synthesis in general consists of two parts, the low frequency ground motion calculated by a numerical method, like FEM, and the high frequency motion synthesized by random approach, and the result of the former is in three dimensional, while that of the latter has just horizontal component. The vertical acceleration time histories proposed in the paper show the way is available.

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Seismic Analysis of a Turbine on a Spring Isolated Pedestal

Volume 3: Dynamic Systems and Controls, Symposium on Design and Analysis of Advanced Structures, and Tribology ◽

10.1115/esda2006-95818 ◽

2006 ◽

Cited By ~ 1

Author(s):

Victor V. Kostarev ◽

Andrei V. Petrenko ◽

Peter S. Vasilyev ◽

Alexander S. Lisyansky

Keyword(s):

High Speed ◽

Seismic Isolation ◽

System Analysis ◽

Seismic Analysis ◽

Full Range ◽

Coupled Model ◽

Time History ◽

Soil Conditions ◽

Isolation System ◽

Detailed Model

Paper deals with the detailed seismic analysis of powerful high-speed Russian turbine of Nuclear Power Plant. Dozens of patterns of such turbine work reliably since 70’s worldwide. Until last decade only simplified structural analyses were available due to a complicated overall structure and internals of such turbines. The current analysis considers detail geometry of the turbine itself as well as vibration and seismic isolation system within turbine’s pedestal and full range of operational, accident and seismic loads. To solve the problem of the turbine seismic and dynamic qualification the following steps have been done. On the first step detailed finite element models of turbine’s high and low pressure parts and rotor system with bearings were created. Using such models corresponding simplified models were developed to be included into the coupled model of the system: “Building – Vibroisolation Pedestal – Turbine” (BVT). The second step was the analysis of that coupled system. Soil-structure interaction was considered using actual soil conditions. Three components of time history acceleration were used to define seismic excitation. As the result of BVT system analysis a full picture of time history displacements and loads were determined. At the same time a non-linear problem of rotor’s axial and radial bearings behavior and gaps in the system was solved. On the final step determined loads were applied to the detailed model of turbine for seismic and dynamic qualification of the whole structure.

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