Seismic design of base-isolated highway bridges utilizing lead–rubber bearings

1990 ◽  
Vol 17 (3) ◽  
pp. 413-422 ◽  
Author(s):  
A. Ghobarah ◽  
H. M. Ali
Keyword(s):  
Seismic Design ◽  
Base Isolation ◽  
Time History ◽  
Highway Bridges ◽  
Response Spectra ◽  
Design Guidelines ◽  
Design Parameters ◽  
Seismic Behaviour ◽  
Isolation System ◽  
Design Procedures

A study is made of the seismic behaviour of base-isolated highway bridges with the objective of developing design procedures in the form of code-type approach. The recommendations of current codes concerning the use of energy dissipation mechanisms for the seismic design of bridges are reviewed. A model representing the bridge deck, piers, and the base-isolation system is used to evaluate the response of the bridge to a selected earthquake time history record and to evaluate the effects of various design parameters on the dynamic response. The results of this analysis are used in the development of design guidelines for the isolated bridge system. It was found that base isolation affects the design forces on piers and abutments as well as the deck displacements. An optimum design should provide a reasonable balance between the shear forces on supports and tolerable displacements. Two design procedures are proposed based on the time history and inelastic response spectra approaches. Simplified charts are presented which aid in the seismic design of new bridges as well as in the upgrading of existing ones. Key words: dynamic, seismic, design, highway, bridges, earthquake, base isolation.

Design Guidelines for Base-Isolated Buildings with Energy Dissipators

1984 ◽  
Vol 1 (1) ◽  
pp. 41-74 ◽  
Author(s):  
Ronald L. Mayes ◽  
Lindsay R. Jones ◽  
Trevor E. Kelly ◽  
Martin R. Button
Keyword(s):  
Base Isolation ◽  
Design Strategy ◽  
Design Guidelines ◽  
Story Structure ◽  
Isolation System ◽  
Design Procedures ◽  
Design Charts ◽  
Base Isolation System ◽  
Energy Dissipators ◽  
Mechanical Devices

Base isolation is a design strategy founded on the premise that a structure can be substantially decoupled from damaging horizontal components of earthquake motions, significantly reducing levels of force and acceleration in the structure. This paper provides the basis of a practical base isolation system which includes energy dissipation in special purpose mechanical devices. Topics covered include basic elements of base isolation, feasibility, design philosophy and code considerations. Design procedures based on a series of design charts are presented and an example of their use on a 12-story structure is detailed.

Seismic behaviour of highway bridges with base isolation

1988 ◽  
Vol 15 (1) ◽  
pp. 72-78 ◽  
Author(s):  
A. Ghobarah
Keyword(s):  
Base Isolation ◽  
Highway Bridges ◽  
Design Guidelines ◽  
Earthquake Ground Motion ◽  
System Response ◽  
Seismic Behaviour ◽  
Long Span ◽  
Proper Design ◽  
Ground Motion Records ◽  
Bridge System

A study is made on the seismic behaviour of highway bridges with lead–rubber base isolation. The system of base isolation is considered as a bilinear spring. Single- and two-span highway bridges subjected to representative strong earthquake ground motion records were analyzed. The effect of various parameters such as the isolator's stiffness, pier stiffness, and pier eccentricity on the system response was evaluated.It was found that the use of base isolation shifts the fundamental frequency of the bridge system towards the longer period. Proper design of the base isolation tends to reduce the design forces on the bridge piers and is accompanied by larger displacements. Simplified design guidelines are adequate as long as the bridge system can be represented by a single degree of freedom model. The reduction in pier stiffness of a two-span bridge may increase the displacement and the force transmitted to the abutment. The increased forces at the abutments are accompanied by reduction in the shear force transmitted to the pier. Increased displacements and forces may also result when the location of the pier departs from the centre and unequal spans are created. In this case, the maximum displacements and forces occur at the abutment adjacent to the long span. Key words: dynamic, seismic, response, highway, bridges, earthquake, base isolation, design.

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.

Dynamic Nonlinear Analysis of an Hybrid Base Isolation System with Viscous Dampers and Friction Sliders in Parallel

2012 ◽  
Vol 234 ◽  
pp. 96-101 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis
Keyword(s):  
Nonlinear Analysis ◽  
Base Isolation ◽  
Three Dimensional ◽  
Time History ◽  
Seismic Action ◽  
Viscous Dampers ◽  
Isolation System ◽  
Fixed Base ◽  
Base Isolation System ◽  
Dynamic Nonlinear Analysis

In the present work we have analyzed a particular base isolation system for the seismic protection of a multi-storey reinforced concrete (RC) building. The viscous dampers and friction sliders are the devices adopted in parallel for realizing the base isolation system. The base isolation structure has been designed and verified according to European seismic code EC8 and by considering for the friction sliders the influence of the sliding velocity on the value of the friction coefficient. A dynamic nonlinear analysis for a three-dimensional base isolated structure has been performed. Recorded accelerograms for bi-directional ground motions have been used which comply with the requirements imposed by EC8 for the representation of a seismic action in a time history analysis. In this paper a comparative analysis is presented between the base isolated structure with the described hybrid base isolation system and the traditional fixed base structure.

scholarly journals The effect of seismic base isolation on structural response of a 12-story hotel building in Padang, Indonesia

2020 ◽  
Vol 156 ◽  
pp. 05026
Author(s):  
Fauzan ◽  
Afdhalul Ihsan ◽  
Mutia Putri Monika ◽  
Zev Al Jauhari
Keyword(s):  
Base Isolation ◽  
Response Spectrum ◽  
Soft Soil ◽  
Structural Response ◽  
Time History ◽  
Seismic Zone ◽  
Isolation System ◽  
Rubber Bearing ◽  
Seismic Base Isolation ◽  
The City

The amount of potential investment in Padang City, Indonesia since 2017 attracted many investors to contribute to the city. One of the investments is a 12-story hotel that will be constructed in By Pass Street of the city. The hotel is located in a high seismic zone area, so the seismic base isolation has been proposed to be used in the hotel building. The main aim of using a seismic base isolation device is to reduce the inertia forces introduced in the structure due to earthquakes by shifting the fundamental period of the structure out of dangerous resonance range and concentration of the deformation demand at the isolation system. An analytical study on the Reinforced Concrete (RC) hotel building with and without rubber bearing (RB) base isolation is carried out using the response spectrum and time history analysis methods. The results show that internal forces and inter-story drift of the building with high damping rubber bearing (HDRB) are lower than that of the fixed base with a remarkable margin. From this study, it is recommended to use the HDRB base isolation for medium and high rise buildings with soft soil in Padang City, Indonesia.

scholarly journals Simplified Method for the Seismic Design of Low-Rise, Shear Wall Base- Isolated Buildings

2014 ◽  
Vol 8 (1) ◽  
pp. 22-33
Author(s):  
Arturo Tena-Colunga
Keyword(s):  
Seismic Design ◽  
Hybrid Method ◽  
Base Isolation ◽  
Shear Wall ◽  
Static Method ◽  
Isolation System ◽  
Strong Earthquakes ◽  
Wall Structures ◽  
Simplified Method ◽  
Isolated Structures

A simplified method for the seismic design of low-rise, base-isolated shear wall structures is proposed in MOC-2012. This simplified method is basically a hybrid method, where the design of the isolation system is a simpler version for the static method available in US guidelines for the design of base-isolated structures and the design of the superstructure essentially is an improved version of the simplified method for the seismic design of conventional low-rise shear wall structures of Mexican seismic codes. The application of this method and its effectiveness to obtain safe designs is illustrated with a practical example. It is anticipated this simple methodology would help promote the use of base isolation in low-rise shear wall structures and reduce their vulnerability when subjected to strong earthquakes.

A genetic algorithm–based design approach for smart base isolation systems

2017 ◽  
Vol 29 (7) ◽  
pp. 1315-1332 ◽  
Author(s):  
Mohtasham Mohebbi ◽  
Hamed Dadkhah ◽  
Hamed Rasouli Dabbagh
Keyword(s):  
Genetic Algorithm ◽  
Optimization Problem ◽  
Base Isolation ◽  
Design Procedure ◽  
Design Parameters ◽  
Linear Quadratic ◽  
Isolation System ◽  
Isolation Systems ◽  
Magneto Rheological ◽  
Smart Base Isolation

This article presents a new approach for designing effective smart base isolation systems composed of a low-damping linear base isolation and a semi-active magneto-rheological damper. The method is based on transforming the design procedure of the hybrid base isolation system into a constrained optimization problem. The magneto-rheological damper command voltages have been determined using H2/linear quadratic Gaussian and clipped-optimal control algorithms. Through a sensitivity analysis to identify the effective design parameters, base isolation and control algorithm parameters have been taken as design variables and optimally determined using genetic algorithm. To restrict increases in floor accelerations, the objective function of the optimization problem has been defined as minimizing the maximum base drift while putting specific constraint on the acceleration response. For illustration, the proposed method has been applied to design a semi-active hybrid isolation system for a four-story shear building under earthquake excitation. The results of numerical simulations show the effectiveness, simplicity, and capability of the proposed method. Furthermore, it has been shown that using the proposed method, the acceleration of the isolated structure can also be incorporated into design process and practically controlled with a slight sacrifice of control effectiveness in reducing the base drift.

Evaluation of the Isolation System Influence in the Seismic Loading Analysis Applied to a Near Term Deployment Reactor

2009 ◽  
Author(s):  
R. Lo Frano ◽  
G. Forasassi
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Seismic Waves ◽  
Base Isolation ◽  
Methodological Approach ◽  
Response Spectra ◽  
Three Dimensional Model ◽  
Isolation System ◽  
Isolation Technique ◽  
Near Term

Nuclear power plant (NPP) design is strictly dependent on the seismic hazards and safety aspects related to the external events of the site. Passive vibration isolators are the most simple and reliable means to protect sensitive equipment from environmental shocks and vibrations. This paper concerns the methodological approach to treat isolation applied to a near term deployment reactor and its internals structures in order to attain a suitable decrease of response spectra at each floor along the height of the structure. The aim of this evaluation is to determine the seismic resistance capability of as-built structures systems and components in the event of the considered Safe Shutdown earthquake (SSE). The use of anti-seismic techniques, such as seismic isolation (SI) and passive energy dissipation, seems able to ensure the full integrity and operability of important structures and systems even in very severe seismic conditions. Therefore the seismic dynamic loadings, propagated up to the main reactor system and components, may be reduced by using the developed base-isolation system (high flexibility for horizontal motions) that might combine suitable dampers with the isolating components to support reactor structures and building. To investigate and analyze the effects of the mentioned earthquake on the considered reactor internals, a deterministic methodological approach, based on the evaluation of the propagation of seismic waves along the structure, was used. To the purpose of this study a numerical assessment of dynamic structural response behaviour of the structures was accomplished by means of the finite element approach and setting up, as accurately as possible, a representative three-dimensional model of mentioned NPP structures. The obtained results in terms of response spectra (carried out from both cases of isolated and not isolated seismic analyses) were compared in order to highlight the isolation technique effectiveness.

Development of Structural Design Guidelines for Porous Asphalt Pavement

2018 ◽  
Vol 2672 (40) ◽  
pp. 197-206 ◽  
Author(s):  
Kevin D. Hall ◽  
Charles W. Schwartz
Keyword(s):  
Structural Design ◽  
Design Procedure ◽  
Field Performance ◽  
Design Guidelines ◽  
Empirical Approach ◽  
Asphalt Pavements ◽  
Design Parameters ◽  
Extensive Literature ◽  
Porous Asphalt ◽  
Design Procedures

Porous asphalt pavements allow designers to introduce more sustainability into projects and lessen their environmental impact. Current design procedures are based primarily on hydrologic considerations; comparatively little attention has been paid to their structural design aspects. As their use grows, a design procedure and representative material structural properties are needed to ensure that porous pavements do not deteriorate excessively under traffic loads. The objective of this project was to develop a simple, easy to apply design procedure for the structural design of porous asphalt pavements. Two methodologies were considered for such a structural design procedure: ( a) the 1993 AASHTO Pavement Design Guide empirical approach, and ( b) the mechanistic–empirical approach employed by the AASHTOWare Pavement ME Design software. A multifactor evaluation indicated the empirical 1993 AASHTO design procedure to be the most appropriate platform at this time. It is noted, however, that both design procedures lack validation of porous asphalt pavements against field performance. AASHTO design parameters and associated material characteristics are recommended, based on an extensive literature review. For “thin” open-graded base structures (12 in. or less), the AASHTO procedure is performed as published in the 1993 Guide. For “thick” base structures (>12 in.), the base/subgrade combination is considered a composite system which supports the porous asphalt layer; an equivalent deflection-based approach is described to estimate the composite resilient modulus of the foundation system, prior to applying the 1993 AASHTO design procedure.

Effect of Friction Bearing Ratio on Isolation Performance and Nonlinear Property in Parallel Composite Isolation System

2013 ◽  
Vol 639-640 ◽  
pp. 896-900
Author(s):  
Ying Yuan ◽  
Ai Hong Zhou ◽  
Yan Li Gao
Keyword(s):  
Base Isolation ◽  
Time History ◽  
Analysis Method ◽  
Isolation System ◽  
Nonlinear Properties ◽  
History Analysis ◽  
Friction Bearing ◽  
Key Factor ◽  
Hysteretic Characteristics ◽  
Isolation Performance

Different friction bearing ratios have effects on the base isolation property of parallel composite isolation system subjected to the seismic excitation. In order to deeply investigate how the friction bearing ratio affect the isolation property, the numerical simulation was carried out by the time-history analysis method, in which the seismic response of parallel composite isolation system with different friction bearing ratios under different acceleration peak values were calculated. Then, the effects of different friction bearing ratios on the base maximum shear coefficients and base maximum displacements; the hysteretic characteristics and nonlinear properties were analyzed and discussed. The results show that, for the parallel composite isolation system, friction bearing ratio is a key factor affecting the isolation property and the nonlinear properties are tightly related to the friction bearing ratio and acceleration peak values.

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