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Sajedi_Siavash_Final Dissertation.pdf (2.53 MB)

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RELIABILITY-BASED DESIGN OPTIMIZATION OF CORROSION MANAGEMENT STRATEGIES FOR REINFORCED CONCRETE STRUCTURES

Sajedi, Siavash
http://rave.ohiolink.edu/etdc/view?acc_num=akron1503333406583485

Abstract Details

2017, Doctor of Philosophy, University of Akron, Civil Engineering.
Chloride induced corrosion is known as the dominant cause of premature damage in reinforced concrete (RC) bridges in the United States. However, the current corrosion management strategies do not suggest a suitable procedure for performance evaluation and optimum design/repair of RC bridges in corrosive environments. Corrosion affects the integrity of the RC structure by deteriorating the material properties and the bond at the steel-concrete interface. In this study, first, a simple probabilistic model of bond strength considering corrosion effect is developed using multivariable regression technique based on a comprehensive database collected from the literature. The predictions are found to be accurate and unbiased when compared with the experimental results. The proposed bond model is employed in the nonlinear finite element models of intact and corroded RC beams to investigate the importance of steel-concrete bond modeling on evaluating flexural behavior of the beams. Then, the minimum required development length for a given corrosion level is calculated and its sufficiency is investigated through a numerical analysis. In the next step, an analytical procedure is proposed for predicting the nonlinear flexural behavior of intact and corroded RC beams with or without lap splices using the developed bond strength. The proposed analytical procedure can facilitate the performance evaluation and reliability assessment of the existing intact/corroded RC structures. The accuracy of the proposed procedure is verified through several experimental and numerical case studies. Furthermore, the proposed procedure is applied to predict the flexural behavior of intact and corroded T-beams of an RC bridge and the results are verified though the finite element analyses. Next, a module based on a reliability-based multi-objective design optimization (RB-MODO) technique using a non-dominated sorting genetic algorithm II (NSGA-II) is developed for the optimum design of RC bridge beams considering corrosion effects. The procedure simultaneously maximizes the reliability of the structure and minimizes the material costs, given a design service life. Note that the analytical procedure developed in the previous section can be incorporated into the RB-MODO technique for optimum design of the structures based on both ultimate and serviceability performances. As an illustration, the developed RB-MODO technique is used for optimum flexural design of an interior T-beam of an illustrated RC bridge with and without considering corrosion effects subjected to various design constraints and service lives. Three types of materials are used in the design process: normal strength concrete with black steel rebars (NSC-BS), normal strength concrete with epoxy coated rebars (NSC-EC), and high performance concrete with black steel rebars (HPC-BS). Then, the optimum design strategy is selected among the considered materials based on the Pareto front results obtained from the proposed RB-MODO procedure. Lastly, a reliability-based life-cycle-cost-analysis (LCCA) approach is developed to compare the long-term cost effectiveness of using six commonly-used groups of materials in design and repair of RC structures, including: NSC-BS, NSC-EC, NSC-SS (NSC with stainless steel (SS) rebars), HPC-SF-BS (high performance concrete (HPC) containing Silica Fume (SF) with BS rebars), HPC-SL-BS (HPC containing Slag (SL) with BS rebars), and HPC-FA-BS (HPC containing Fly Ash (FA) with BS rebars). A reliability-based design optimization (RBDO) technique is used for optimum initial design of the structure for each group of materials through minimizing the initial costs, given a target ultimate reliability index. Then, reliability analysis is conducted to evaluate the time-dependent serviceability and ultimate performances of the structure, and to predict the time-to repair and the number of repair operations. Lastly, LCCA is conducted to select the optimum corrosion management strategy in terms of selecting an optimum material for design and repair of the RC structures in corrosive areas.
Qindan Huang (Advisor)
Civil Engineering
Corrosion; repair; steel-concrete bond; load-deflection prediction; FE analysis; reliability analysis; multi-objective optimization; life-cycle-cost-analysis; RC bridge

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Citations

  • Sajedi, S. (2017). RELIABILITY-BASED DESIGN OPTIMIZATION OF CORROSION MANAGEMENT STRATEGIES FOR REINFORCED CONCRETE STRUCTURES [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1503333406583485

    APA Style (7th edition)

  • Sajedi, Siavash. RELIABILITY-BASED DESIGN OPTIMIZATION OF CORROSION MANAGEMENT STRATEGIES FOR REINFORCED CONCRETE STRUCTURES. 2017. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1503333406583485.

    MLA Style (8th edition)

  • Sajedi, Siavash. "RELIABILITY-BASED DESIGN OPTIMIZATION OF CORROSION MANAGEMENT STRATEGIES FOR REINFORCED CONCRETE STRUCTURES." Doctoral dissertation, University of Akron, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1503333406583485

    Chicago Manual of Style (17th edition)

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