Vulnerability-Based Design of Sliding Concave Bearings for the Seismic Isolation of Steel Storage Tanks

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Silvia Alessandri ◽  
Phuong Hoa Hoang
Keyword(s):  
Liquid Steel ◽  
Seismic Isolation ◽  
Failure Modes ◽  
Fragility Curves ◽  
Time History ◽  
Probability Of Failure ◽  
Design Parameters ◽  
Economic Losses ◽  
Storage Tanks ◽  
Isolation System

Liquid steel storage tanks are strategic structures for industrial facilities and have been widely used both in nuclear and non-nuclear power plants. Typical damage to tanks occurred during past earthquakes such as cracking at the bottom plate, elastic or elastoplastic buckling of the tank wall, failure of the ground anchorage system, and sloshing damage around the roof, etc. Due to their potential and substantial economic losses as well as environmental hazards, implementations of seismic isolation and energy dissipation systems have been recently extended to liquid storage tanks. Although the benefits of seismic isolation systems have been well known in reducing seismic demands of tanks; however, these benefits have been rarely investigated in literature in terms of reduction in the probability of failure. In this paper, A vulnerability-based design approach of a sliding concave bearing system for an existing elevated liquid steel storage tank is presented by evaluating the probability of exceeding specific limit states. Firstly, nonlinear time history analyses of a three-dimensional stick model for the examined case study are performed using a set of ground motion records. Fragility curves of different failure modes of the tank are then obtained by the well-known cloud method. In the following, a seismic isolation system based on concave sliding bearings is proposed. The effectiveness of the isolation system in mitigating the seismic response of the tank is investigated by means of fragility curves. Finally, an optimization of design parameters for sliding concave bearings is determined based on the reduction of the tank vulnerability or the probability of failure.

scholarly journals Evaluating Collapse Fragility Curves for Existing Buildings Retrofitted Using Seismic Isolation

2020 ◽  
Vol 10 (8) ◽  
pp. 2844
Author(s):  
Amedeo Flora ◽  
Giuseppe Perrone ◽  
Donatello Cardone
Keyword(s):  
Seismic Isolation ◽  
Failure Modes ◽  
Base Isolation ◽  
Fragility Curves ◽  
Limit State ◽  
Spectral Acceleration ◽  
Existing Buildings ◽  
Isolation System ◽  
Isolation Technique ◽  
Design Earthquake

Few studies have investigated so far the collapse capacity of buildings with base-isolation. In such studies, preliminary considerations have been drawn based on a number of assumptions regarding: (i) the methodology used for assessing the collapse capacity, (ii) the collapse conditions and failure modes assumed for both superstructure and isolation system, and (iii) the numerical modeling assumptions. The main results pointed out that the collapse conditions of base-isolated buildings may occur for intensity levels slightly higher than those associated with the design earthquake. In this paper, further developments are made through the use of enhanced models for the description of the behavior of a rubber-based isolation system and the assumption of more rational collapse conditions. Collapse fragility functions, in terms of mean and dispersion values, are proposed for two archetypes representative of existing buildings retrofitted using the seismic isolation technique. The collapse margin ratio (median collapse capacity Sa,C, namely the spectral acceleration associated to a probability of exceedance equal to 50%, divided by the design spectral acceleration at the collapse prevention limit state) has been evaluated for each examined case-study. Values ranging from 1.10 to 1.45 were found.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 3 — Seismic Response of Crossover Piping for Seismic Isolation System

2014 ◽  
Author(s):  
Akihito Otani ◽  
Teruyoshi Otoyo ◽  
Hideo Hirai ◽  
Hirohide Iiizumi ◽  
Hiroshi Shimizu ◽  
...  
Keyword(s):  
Seismic Response ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Response Spectrum ◽  
Time History ◽  
Response Analysis ◽  
Isolation System ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper, which is part of the series entitled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”, shows the linear seismic response of crossover piping installed in a seismically isolated plant. The crossover piping, supported by both isolated and non-isolated buildings, deforms with large relative displacement between the two buildings and the seismic response of the crossover piping is caused by two different seismic excitations from the buildings. A flexible and robust structure is needed for the high-pressure crossover piping. In this study, shaking tests on a 1/10 scale piping model and FEM analyses were performed to investigate the seismic response of the crossover piping which was excited and deformed by two different seismic motions under isolated and non-isolated conditions. Specifically, as linear response analysis of the crossover piping, modal time-history analysis and response spectrum analysis with multiple excitations were carried out and the applicability of the analyses was confirmed. Moreover, the seismic response of actual crossover piping was estimated and the feasibility was evaluated.

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.

Seismic Analysis of a Turbine on a Spring Isolated Pedestal

2006 ◽  
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.

Study of Parameters Optimization on Seismic Isolated Railway Bridges

2011 ◽  
Vol 50-51 ◽  
pp. 135-139
Author(s):  
Tie Yi Zhong ◽  
Chao Yi Xia ◽  
Feng Li Yang
Keyword(s):  
Optimal Design ◽  
Optimization Design ◽  
Seismic Isolation ◽  
Optimization Method ◽  
Relative Displacement ◽  
Parameters Optimization ◽  
Design Parameters ◽  
Isolation System ◽  
Railway Bridges ◽  
Design Variables

Based on optimization theories, considering soil-structure interaction and running safety, the optimal design model of the seismic isolation system with lead-rubber bearings (LRB) for a simply supported railway beam bridge is established by using the first order optimization method in ANSYS, which the parameters of the isolation bearing are taken as design variables and the maximum moments at the bottom of bridge piers are taken as objective functions. The optimal calculations are carried out under the excitation of three practical earthquake waves respectively. The research results show that the ratio of the stiffness after yielding to the stiffness before yielding has important effect on the structural seismic responses. Through the optimal analysis of isolated bridge system, the optimal design parameters of isolation bearing can be determined properly, and the seismic forces can be reduced maximally as meeting with the limits of relative displacement between pier top and beam, which provides efficient paths and beneficial references for dynamic optimization design of seismic isolated bridges.

Improvement of the polyurethane spring isolation device for HV post insulators and its evaluation by fragility curves

2021 ◽  
pp. 875529302098196
Author(s):  
Tansu Gökçe ◽  
Engin Orakdöğen ◽  
Ercan Yüksel
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Numerical Models ◽  
Fragility Curves ◽  
Low Cost ◽  
Steel Plates ◽  
Isolation System ◽  
Base Isolation System ◽  
Isolation Device ◽  
Seismic Base Isolation

A novel seismic base isolation system has been developed for high-voltage (HV) porcelain post insulators. The seismic isolation device consists of two steel plates, four polyurethane springs, and a steel rod, which are low-cost components compared to the post insulators. Two alternative designs of the device are experimentally and numerically assessed in this article. A simple and robust numerical model consisting of linear line elements and nonlinear springs was generated, and subsequently validated using the experimental results. Incremental dynamic analyses (IDAs) were then performed to obtain fragility curves. Ten historical earthquake profiles, scaled to intensities between 0.1 and 2.0 g, were then applied to the numerical models. The fragility curves, generated according to the latest version of IEEE-693, demonstrate that the seismic isolation devices are highly effective in diminishing the base moment of the porcelain insulator. It should be noted that relatively large displacements at the top of the pole must be accounted for by ensuring adequate slackness in the flexible conductors.

scholarly journals Seismic fragility analysis for tall pier bridges with rocking foundations

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Xu Chen ◽  
Jianzhong Li
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Fragility Curves ◽  
Dynamic Performance ◽  
Time History ◽  
Element Model ◽  
Nonlinear Time History Analysis ◽  
Promising Alternative ◽  
Demand Models ◽  
Rocking Foundations

AbstractCostal bridge systems usually contain tall piers with heights over 40 m, due to the engineering site exposed to deep water circumstances. Note that the conventional seismic isolation devices (e.g., isolation bearings) are not that effective for tall piers, since their dynamic performance is significantly affected by the distributed mass and vibration modes of columns; therefore, base isolation design philosophy could be a promising alternative for mitigating seismic demands of this type of bridges. This paper mainly investigates the efficiency of rocking foundations in improving seismic performance of tall pier bridges, with the results presented in the format of fragility curves. Finite element model of the prototype tall pier bridge is developed, and the responses subjected to near-fault motions are obtained using nonlinear time history analysis. Probability seismic demand models and fragility curves are then developed accordingly, based on which the performance of tall pier bridges are assessed. The results show that employment of rocking foundations could significantly reduce the demands of tall piers and the probability of being damaged. Before the initiation of uplifting at pier base, the behavior of rocking piers resembles that of conventional ones with integrated foundation. While rocking initiates under strong excitations, the demands of rocking piers reduce drastically compared with integrated ones and tend to be similar under different motions, which benefits the post-earthquake performance assessment of these bridges.

scholarly journals Seismic Isolation System using U-Shaped Steel Damper

2019 ◽  
Vol 8 (4) ◽  
pp. 12336-12339
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Structural Response ◽  
Time History ◽  
Earthquake Ground Motion ◽  
Isolation System ◽  
Isolation Technique ◽  
Base Isolation System ◽  
The Time Domain ◽  
External Forces

In the present paper base isolation system is analyzed and its seismic behavior is investigated using U-shaped steel dampers as an isolator by placing it at the bottom of the structure. It is the most popular way of protecting the structure using control techniques for earthquake ground motion. The dampers significantly reduced damage factors such as displacement and drift. To reduce structural response to external forces, which can be accomplished through the use of special protective systems. So to prevent these damages, seismic isolation technique can be used for newly constructed structures. The time history analysis of the time domain on this structure is conducted by using SAP2000 software

Effect of sliding pendulum isolator bearing to the structural performance of Becakayu Ahmad-Yani continuous span bridge

2021 ◽  
Author(s):  
Tri Suryadi ◽  
Tony Sihite ◽  
Wanda Heryudiasari
Keyword(s):  
Seismic Isolation ◽  
Passive Control ◽  
Linear Time ◽  
Time History ◽  
Structural Performance ◽  
Easy Access ◽  
Isolation System ◽  
Toll Road ◽  
History Analysis ◽  
Road Project

<p>Structural assessment is an important procedure to be done for checking and reviewing the realization of the expected structural performance level. In a normal circumstance, it is common that the bridge is designed with life-safety performance that implies undamaged superstructures and foundations, and damaged substructures. This design philosophy is normally known as “ductile substructure and elastic superstructure” concept. The location of the damages shall be predefined to allow easy access for future repairs after earthquake events. Nowadays, a different design approach is introduced through the use of passive control devices. One of the most common technology for bridges is the seismic isolation system using sliding pendulum isolator bearing as the seismic controlling device. Ahmad Yani Continuous Span Bridge in Becakayu Toll Road Project is designed with pendulum isolator bearings. Through non-linear time history analysis, the structural performance of Ahmad Yani Bridge will be evaluated. It is expected that all the dissipation mechanism occurs in the pendulum bearings, with both superstructure and substructures are still in elastic and essentially elastic conditions.</p>

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.

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