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Probabilistic Characterization of Bond Behavior at Rebar-concrete Interface in Corroded RC Structures: Experiment, Modeling, and Implementation

Soraghi, Ahmad
http://orcid.org/0000-0001-8582-0347
http://rave.ohiolink.edu/etdc/view?acc_num=akron1638113761163502

Abstract Details

2021, Doctor of Philosophy, University of Akron, Civil Engineering.
Adequate rebar-concrete bonding is crucial to ensure the reliable performance of reinforced concrete (RC) structures. Many factors (such as the concrete properties, concrete cover depth, transverse reinforcement, and the presence of corrosion) affect the bond behavior, and consequently the structural performance. This bond behavior is typically described by a bond stress-slip relationship, where there are two critical quantities: bond strength ̶ the maximum shear stress that bond can withstand, and peak slip ̶ the slippage at the interface when the bond strength is reached. It is understood that the bond deteriorates when corrosion is present and behaves differently under two distinct bond failure modes (i.e., splitting and pull-out). While many prior studies have focused on the influence of the aforementioned factors on the bond strength, the impact of the failure mode coupled with corrosion on the bond stress-slip relationship and structural performance have not been thoroughly investigated. This study is aimed to address this issue. In this study, first a probabilistic bond failure mode prediction model that considers various influencing factors including loading type and corrosion is developed in this study. This study uses the bond testing results of 132 beam-end specimens subjected to monotonic and cyclic loading and adopts classification methods to develop the prediction model, which is then used to evaluate the impact of bond behavior on the reliability of a RC beam with a lap splice. Then, multivariate nonlinear regression with all-possible subset model selection and symbolic multi-gene regression are adopted for probabilistic model development for bond strength and peak slip under the two bond failure modes considering corrosion. In particular, a comprehensive bond dataset collected from bond tests on the beam and beam-end specimens in the literature and from the experimental testing conducted in this study, and a criterion to specify the bond failure mode is also proposed. Next, incorporating bond in the structural analysis is investigated. Since in reality, perfect bonding does not exist, especially in beam and column or column and footing connections, reinforcement slip occurs as a result of imperfect bonding. Reinforcement slip in the footing of a RC column can significantly influence the lateral displacement of the column, a critical structural response under lateral loads such as seismic loading. Many past researchers studied and developed models to capture the anchorage slip of rebar; however, a model that can reflect the actual bond-slip relationship (especially in the presence of corrosion) and yet be simple-to-use for structural analysis is not well developed. In this study, a new simple bar stress-slip macromodel is developed to predict reinforcement anchorage slip given a rebar stress. The proposed rebar anchorage slip model is derived by implementing a macromodel solution based on a simple bond stress distribution function that captures the bond stress distribution numerically obtained from a real bond-slip relationship. Available experimental bond stress-slip data collected from literature are used to optimize the model parameter in the proposed bond stress distribution function, which reflects the impact of the structural parameters on the rebar slippage such as concrete strength and corrosion level. The proposed rebar slip model is then incorporated into a fiber beam-column model for numerical analysis, and is further validated by comparing flexural behavior of several RC columns (with and without corrosion) based on the numerical model with the experimental data. The results demonstrate the importance of incorporating rebar slippage and corrosion effect on bond. Using this fiber beam-column model, seismic performance of an example RC bridge column is evaluated, and one can conclude the rebar slip plays a critical role in the seismic evaluation. As the proposed rebar slip macromodel provides simple formulation and it is explicitly expressed with a model parameter that can be updated easily to incorporate new information, it is practical for application in the structural analysis.
Qindan Huang (Advisor)
David Roke (Committee Member)
Craig Menzemer (Committee Member)
Ping Yi (Committee Member)
Richard Einsporn (Committee Member)
231 p.
Civil Engineering; Design; Engineering; Experiments
Reinforced Concrete, Bond; Corrosion, Probabilistic Models; Classification Methods; Reliability; Bond Strength; Peak slip Model; Bond Failure Mode; Bond Stress-slip Behavior; Multivariate Nonlinear Regression; Symbolic Multi-Gene Regression; Rebar slip; Bond stress distribution; Macromodel; Corrosion; RC column; Fiber Beam-column model

Recommended Citations

Citations

  • Soraghi, A. (2021). Probabilistic Characterization of Bond Behavior at Rebar-concrete Interface in Corroded RC Structures: Experiment, Modeling, and Implementation [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1638113761163502

    APA Style (7th edition)

  • Soraghi, Ahmad. Probabilistic Characterization of Bond Behavior at Rebar-concrete Interface in Corroded RC Structures: Experiment, Modeling, and Implementation. 2021. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1638113761163502.

    MLA Style (8th edition)

  • Soraghi, Ahmad. "Probabilistic Characterization of Bond Behavior at Rebar-concrete Interface in Corroded RC Structures: Experiment, Modeling, and Implementation." Doctoral dissertation, University of Akron, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1638113761163502

    Chicago Manual of Style (17th edition)

akron1638113761163502
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This open access ETD is published by University of Akron and OhioLINK.