Seismic Performance of Seat-Type Abutment Highway Bridges in Illinois

LaFave, James M.; Fahnestock, Larry A.; Luo, Jie; Kozak, Derek L.

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https://hdl.handle.net/2142/100877 Copy

Description

Title

Seismic Performance of Seat-Type Abutment Highway Bridges in Illinois

Author(s)

• LaFave, James M.
• Fahnestock, Larry A.
• Luo, Jie
• Kozak, Derek L.

Issue Date

2018-08

Keyword(s)

• Earthquake engineering
• highway bridges
• bridge bearings
• seismic isolation
• quasi-isolation
• skew bridges
• multi-column piers
• soil structure interaction

Abstract

This study assesses the seismic performance of quasi-isolated highway bridges with seat-type abutments, validates the current IDOT design strategy, and provides recommendations for improving a bridge’s seismic behavior. To encompass common configurations of highway bridges with non-seismically designed bearing components employed as sacrificial connections between superstructures and substructures, a suite of prototype bridges with variations in span arrangement, girder type, skew angle, pier column height, and foundation soil condition were studied. Detailed three-dimensional nonlinear finite-element models were developed for the bridges, incorporating various critical structural components and geotechnical mechanisms. Multi-mode adaptive pushover analyses were conducted to investigate bridge response characteristics in terms of the force distribution among substructures, the sequence of limit state occurrences, the fusing of sacrificial connections, and the vulnerability of critical bridge components. Eigenvalue modal analyses were also performed in the elastic and inelastic deformation states to reveal modal response characteristics of the bridges. The study culminated in an extensive seismic performance assessment of quasi-isolated bridges, for which thousands of nonlinear dynamic time-history analyses were carried out. The bridges were subjected to a suite of site-specific earthquake ground motions, taking into account the site condition and the regional seismicity of Cairo, Illinois. Assessment results validated that the current quasi-isolation bridge design strategy is generally effective, and the majority of the studied prototype bridges are unlikely to fail in global collapse when subjected to horizontal earthquake ground motions with a 1,000-year return period in deep southern Illinois. Although most of the prototype bridges exhibited satisfactory seismic performance, the response of a small number of them demonstrated a risk of bearing unseating and severe pier column damage. With the aim of improving the seismic performance of these bridges, preliminary recommendations for calibrating the current design strategy were proposed, and their efficacy was demonstrated by comparative studies.

Publisher

Illinois Center for Transportation/Illinois Department of Transportation

Series/Report Name or Number

FHWA-ICT-18-013

ISSN

0197-9191

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/100877

Sponsor(s)/Grant Number(s)

IDOT-R27-133

Copyright and License Information

No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.

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