Effect of Asynchronous Earthquake Motion on Complex Bridges. I: Methodology and Input Motion |
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Authors: | Nicholas J. Burdette Amr S. Elnashai Alessio Lupoi Anastasios G. Sextos |
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Affiliation: | 1Research Assistant, Mid-America Earthquake (MAE) Center, Dept. of Civil Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801 (corresponding author). E-mail: nick.burdette@arup.com 2Bill and Elaine Hall Endowed Professor, Director, MAE Center, Dept. of Civil Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801. E-mail: aelnash@uiuc.edu 3Postdoctoral Research Fellow, Dept. of Structural and Geotechnical Engineering, Univ. of Rome “La Sapienza,” Via Gramsci 53, 00197 Rome, Italy. E-mail: alessio.lupoi@uniroma1.it 4Lecturer, Dept. of Civil Engineering, Division of Structural Engineering, Aristotle Univ. of Thessaloniki, Thessaloniki GR-54124, Greece. E-mail: asextos@civil.auth.gr
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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 parametrized 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 analytical models are analyzed using 2,000 unique synthetic accelerograms with results showing significant response amplification due to asynchronous input motion, demonstrating the importance of considering asynchronous seismic input in complex, irregular bridge design. The paper, Part 1 of a two-paper investigation, presents the development of the input motion sets and the modeling and analysis approach employed, concluding with sample results. Detailed results and implications on seismic assessment are presented in the companion paper: Effect of Asynchronous Motion on Complex Bridges. Part II: Results and Implications on Assessment. |
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Keywords: | Bridges Seismic analysis Seismic effects Earthquakes Ground motion Nonlinear analysis Dynamic analysis |
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