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Title:Seismic behavior and design of integral abutment bridges in southern Illinois
Author(s):Kozak, Derek Lorne
Director of Research:Fahnestock, Larry A.; LaFave, James M.
Doctoral Committee Chair(s):Fahnestock, Larry A.; LaFave, James M.
Doctoral Committee Member(s):Olson, Scott M.; Cha, Eun Jeong
Department / Program:Civil & Environmental Eng
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Integral Abutment Bridge
Earthquake Engineering
Abstract:The increased use of integral abutment bridges (IABs) throughout the United States has led to numerous studies concerning their behavior when subjected to a variety of loads. The seismic behavior of IABs is of particular interest to regions such as southern Illinois, where proximity to the New Madrid Seismic Zone may create significant ground motion accelerations during an earthquake. IABs are common in modern bridge design due to their lack of expansion joints between the superstructure and abutment, which can lead to decreased damage at the abutment seat when compared to stub abutment bridges because water, soil, and deicing chemicals are unable to penetrate through a compromised expansion joint in an IAB. However, elimination of expansion joints in IABs can also lead to the development of complex soil-structure-interaction limit states at the abutment and its foundation when an IAB is subjected to lateral loads. Despite this distinct behavior in IABs when subjected to lateral loading, such as seismic loads, there is a lack of comprehensive system-level studies investigating the behavior of IABs subjected to earthquakes. This dissertation aims to determine the seismic behavior of typical IAB designs in southern Illinois and to develop feedback and recommendations that can improve Illinois IAB seismic designs. This is accomplished through modeling IABs as a whole bridge system, subjecting the IAB models to representative ground motions for southern Illinois, monitoring the behavior of key IAB components, using the monitored results to form a comprehensive view of IAB seismic behavior, and employing the developed knowledge to form recommendations for improving IAB seismic performance. The IAB models are developed in OpenSees through nonlinear modeling of multiple components within an IAB, as well as through connections between the components that allow for interactions between components to be observed. The models represent typical IAB designs for Illinois. They are subjected to 1000-year return period hazard ground motions developed specifically for 10 sites within southern Illinois. Incremental dynamic analyses are also performed, by scaling the ground motion accelerations up and down. IABs with varying superstructure materials, span configurations, bearing layouts, pier heights, and foundation soil conditions are dynamically analyzed using the 10 sets of developed ground motions. The results allow for observations and conclusions to be made concerning the overall seismic performance of current Illinois IAB designs, as well as concerning which components are the most vulnerable to damage during an earthquake. The abutment foundation piles and the pier columns are identified as most vulnerable and frequently encounter severe damage limit states under design-level shaking. Damage to pier columns is especially prominent in IABs with shorter piers and longer abutment-to-abutment spans, while abutment foundation damage, in terms of the yielding, local buckling, and rupture of the piles, frequently occurs in many IAB variants. Recommendations on design modifications to improve the seismic behavior of IABs by limiting the level of damage to these components are also investigated through modifying elastomeric bearing side retainer strength, fixed bearing strength, pier column size, and backfill contributions.
Issue Date:2018-04-17
Rights Information:Copyright 2018 Derek Kozak
Date Available in IDEALS:2018-09-04
Date Deposited:2018-05

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