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.

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.

scholarly journals Earthquake simulation testing of a stepping frame with energy-absorbing devices

1977 ◽  
Vol 10 (4) ◽  
pp. 196-207 ◽  
Author(s):  
J. M. Kelly ◽  
D. F. Tsztoo
Keyword(s):  
Base Isolation ◽  
Shaking Table ◽  
Earthquake Ground Motion ◽  
Earthquake Simulation ◽  
Isolation System ◽  
Steel Bars ◽  
Base Isolation System ◽  
Simulation Testing ◽  
Ground Motion Records ◽  
Energy Absorbing

Results are reported of earthquake simulation tests on a model frame with a partial base isolation system that includes energy-absorbing devices. The isolation system was modeled on a stepping bridge concept developed for the New Zealand Railways, and the energy-absorbing devices, based on the plastic torsion of rectangular mild steel bars, functioned only when the frame base lifted off the foundation. Two series of tests using scaled accelerations from the El Centro N-S 1940 and Pacoima Dam 1971 earthquake ground motion records were used as input to the shaking table on which the tests were performed. Results from these tests are compared to those from earlier tests on an identical frame with the foundation (1) anchored as in conventional design, and (2) permitted to uplift freely. The response of
the frame with the energy-absorbing devices installed was improved over
that of both the fixed frame and the frame allowed to uplift freely for the El Centro accelerations. Although the results are not as favourable for the Pacoima Dam input, the feasibility of the energy-absorbing devices associated with a partial base isolation system is established as an alternative to anchored frames and frames allowed to uplift freely.

scholarly journals Probabilistic seismic response analysis of coastal highway bridges under scour and liquefaction conditions: does the hydrodynamic effect matter?

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Xiaowei Wang ◽  
Yutao Pang ◽  
Aijun Ye
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Highway Bridges ◽  
Element Model ◽  
Response Analysis ◽  
Hydrodynamic Effect ◽  
Strong Earthquakes ◽  
Influence Of Water ◽  
Scour Hazard ◽  
Ground Motion Records

AbstractCoastal highway bridges are usually supported by pile foundations that are submerged in water and embedded into saturated soils. Such sites have been reported susceptible to scour hazard and probably liquefied under strong earthquakes. Existing studies on seismic response analyses of such bridges often ignore the influence of water-induced hydrodynamic effect. This study assesses quantitative impacts of the hydrodynamic effect on seismic responses of coastal highway bridges under scour and liquefaction potential in a probabilistic manner. A coupled soil-bridge finite element model that represents typical coastal highway bridges is excited by two sets of ground motion records that represent two seismic design levels (i.e., low versus high in terms of 10%-50 years versus 2%-50 years). Modeled by the added mass method, the hydrodynamic effect on responses of bridge key components including the bearing deformation, column curvature, and pile curvature is systematically quantified for scenarios with and without liquefaction across different scour depths. It is found that the influence of hydrodynamic effect becomes more noticeable with the increase of scour depths. Nevertheless, it has minor influence on the bearing deformation and column curvature (i.e., percentage changes of the responses are within 5%), regardless of the liquefiable or nonliquefiable scenario under the low or high seismic design level. As for the pile curvature, the hydrodynamic effect under the low seismic design level may remarkably increase the response by as large as 15%–20%, whereas under the high seismic design level, it has ignorable influence on the pile curvature.

Estimation of site amplification and S-wave velocity profiles in metropolitan Manila, the Philippines, from earthquake ground motion records

2011 ◽  
Vol 42 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Hiroaki Yamanaka ◽  
Kaoru Ohtawara ◽  
Rhommel Grutas ◽  
Robert B. Tiglao ◽  
Melchor Lasala ◽  
...  
Keyword(s):  
Ground Motion ◽  
Wave Velocity ◽  
Site Amplification ◽  
Velocity Profiles ◽  
The Philippines ◽  
Earthquake Ground Motion ◽  
S Wave ◽  
Ground Motion Records

scholarly journals A Master Digital Model for Suspension Bridges

2020 ◽  
Vol 10 (21) ◽  
pp. 7666
Author(s):  
Ngoc-Son Dang ◽  
Gi-Tae Rho ◽  
Chang-Su Shim
Keyword(s):  
Suspension Bridge ◽  
Geometrical Model ◽  
Information Modeling ◽  
Digital Model ◽  
Suspension Bridges ◽  
Actual Behavior ◽  
Data Generation ◽  
Element Analysis ◽  
Long Span ◽  
Bridge System

Long-span suspension bridges require accumulated design and construction technologies owing to challenging environmental conditions and complex engineering practices. Building information modeling (BIM) is a technique used to federate essential data on engineering knowledge regarding cable-supported bridges. In this study, a BIM-based master digital model that uses a data-driven design for multiple purposes is proposed. Information requirements and common data environments are defined considering international BIM standards. A digital inventory for a suspension bridge is created using individual algorithm-based models, and an alignment-based algorithm is used to systematize them and generate the entire bridge system. After assembling the geometrical model, metadata and various BIM applications are linked to create the federated master model, from which the mechanical model is derived for further stages. During the construction stage, the advantage of this digital model lies in its capability to perform efficient revisions and updates with respect to varying situations during the erection process. Stability analyses of the bridge system can be performed continuously at each erection step while considering the geometric control simulation. Furthermore, finite element analysis models for any individual structural member can be extracted from the master digital model, which is aimed at estimating the actual behavior of bridge members. In addition, a pilot master digital model was generated and applied to an existing suspension bridge; this model exhibited significant potential in terms of bridge data generation and manipulation.

Load Test Analysis of Long-Span Prestressed Concrete Continuous Beam Bridge

2014 ◽  
Vol 1030-1032 ◽  
pp. 798-801
Author(s):  
Hua Su
Keyword(s):  
Bearing Capacity ◽  
Prestressed Concrete ◽  
Highway Bridges ◽  
Load Test ◽  
Beam Model ◽  
Test Analysis ◽  
Single Beam ◽  
Long Span ◽  
Continuous Beam Bridge ◽  
Girder Bridge

This paper takes a 45+60+45m prestressed concrete continuous box Girder Bridge as background, based on “Specification for Inspection and Evaluation of Load-bearing Capacity of Highway Bridges” (JTG/T J21-2011), single beam model and solid model are built for schematic design of load test. Compare the measured value and the theoretical value, and evaluate the bridge bearing capacity, finally provide technical base for project checking and accepting.

scholarly journals SEISMIC FRAGILITY ASSESSMENT AND RETROFIT OF A GOVERNMENT HOSPITAL BUILDING IN CHITTAGONG, BANGLADESH

2018 ◽  
Vol 30 (1) ◽  
Author(s):  
Md. AbulHasan ◽  
Md. Abdur Rahman Bhuiyan
Keyword(s):  
Ground Motion ◽  
Return Period ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Seismic Fragility ◽  
Earthquake Ground Motion ◽  
Type I ◽  
Type Ii ◽  
Ground Motion Records

Chittagong Medical College Hospital (CMCH) is one of the most important government hospitals in Bangladesh. It is located in the heart of Chittagong city, the only port city of Bangladesh. Bangladesh National Building Code (BNBC) is the only official document, which has been used since 1993 as guidelines for seismic design of buildings. As per the guidelines of BNBC, the CMCH building was designed for an earthquake ground motion having a return period of 200 years. However, the revised version of BNBC has suggested that the building structures shall be designed for an earthquake ground motion having a return period of 2475 years. It is mentioned that a single seismic performance objective, the life safety, of the building is considered in both versions of BNBC. Considering the significant importance of CMCH building in providing the emergency facilities during and after the earthquake, it is indispensable to evaluate its seismic vulnerability for the two types of earthquake ground motion records having return period of 200 (Type-I) and 2475 (Type-II) years. In this regard, this paper deals with the seismic vulnerability assessment of the existing ancillary building (AB) of CMCH. The seismic vulnerability of building is usually expressed in the form of fragility curves, which display the conditional probability that the structural demand (structural response) caused by various levels of ground shaking exceeds the structural capacity defined by a damage state. The analytical method based on elastic response spectrum analyses results is used in evaluating the seismic fragility curves of the building. To the end, 3-D finite element model of the building subjected to 18 ground motion records having PGA of 0.325g to 0.785g has been used in theresponse spectrum analysis in order to evaluate its inter-story-drift ratio (IDR), an engineeringdemand parameter (EDP) for developing fragility curves. The analytical results have shown thatstructural deficiencies exist in the existing ancillary building (AB) for the Type-II earthquakeground motion record, which requires the building to be retrofitted to ensure that the existingancillary building (AB) becomes functional during and after the Type-II earthquake groundmotion record.

Sign in / Sign up

Export Citation Format

Share Document