The Effect of Asynchronous Earthquake Motion on Complex Bridges

Burdette, Nicholas J.; Elnashai, Amr S.; Lupoi, Alessio; Sextos, Anastasios G.

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https://hdl.handle.net/2142/8935 Copy

Description

Title

The Effect of Asynchronous Earthquake Motion on Complex Bridges

Author(s)

• Burdette, Nicholas J.
• Elnashai, Amr S.
• Lupoi, Alessio
• Sextos, Anastasios G.

Issue Date

2006-12

Keyword(s)

• MAE Center
• Asynchronous
• Earthquake
• Bridges

Abstract

Based on observed damage patterns from previous earthquakes and a rich history of analytical studies, asynchronous input motion has been identified as a major source of unfavorable response for long span structures, such as bridges. This study is aimed at quantifying the effect of geometric incoherence and wave arrival delay on complex straight and curved bridges using state-of-the-art methodologies and tools. Using fully parameterized computer codes combining expert geotechnical and earthquake structural engineering knowledge, suites of asynchronous accelerograms are produced for use in inelastic dynamic analysis of the bridge model. Two multi-degree-of-freedom (MDOF) analytical models are analyzed using 2,000 unique synthetic accelerograms. Results from this study indicate that response for the 344 meter study structure is amplified significantly by non-synchronous excitation, with displacement amplification factors between 1.6 and 3.4 for all levels of incoherence. This amplification was not constant or easily predicable, demonstrating the importance of inelastic dynamic analysis using asynchronous motion for assessment and design of this class of structure. Additionally, deck stiffness is shown to significantly affect response amplification, through response comparison between the curved and an equivalent straight bridge. Study results are used to suggest an appropriate domain for consideration of asynchronous excitation as well as an efficient methodology for analysis.

Publisher

Mid-America Earthquake Center

Series/Report Name or Number

MAE Center CD Release 06-03

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/8935

Sponsor(s)/Grant Number(s)

National Science Foundation EEC-9701785

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