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Structural Reliability Study of Highway Bridge Girders Based on AASTHO LRFD Bridge Design Specifications

Dallakoti, Pramish Shakti
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1588538610400668

Abstract Details

2020, Master of Science, University of Toledo, Civil Engineering.
In structural reliability analysis, load and resistance factors are calibrated using various methodologies. Proper calibration of load and resistance factor is essential to obtain the design confidence to meet the design consistency or to obtain a desirable reliability index. The reliability index thus calculated is the measure of the reliability of the structural design. Closed-form solution is an elemental method to determine the reliability index for simpler loads and resistance cases. In some basic cases such as when both loads and resistance are normally or log normally distributed, exact solutions are obtained. But in almost all cases, loads have normal distribution, and resistance has log-normal distribution. In such cases, more rigorous and advance calibration techniques are used to calculate the safety index such as Rackwitz - Fiessler procedure and Monte Carlo Method. In this study, the computer-based Monte Carlo Method was used to calculate the safety index or reliability index. The objective of this study is to describe such methodologies to determine the reliability of the structural designs. In this study, reliability analyses are performed to calibrate load and resistance factors using AASTHO LRFD bridge design specifications for reinforced concrete T-beam bridge girders. Reliability indices are calculated for the three spans continuous bridges with equal span length. Both exterior and interior girders are studied to understand the effect of loads and their trends. Reliability analysis suggests that bending moment is governing over shear. Similarly, there is a significant increase in contributions of dead loads over live load for bending and shear with the increase in span length. Systematic variations of the load and resistance parameters are done to investigate the change in reliability index. Various graphs for reliability index versus sets of statistical and design parameters are plotted for the parametric study. Separate graphs are plotted to understand the trend of the change in the reliability index with such parameters. The study showed that there is an increase in reliability index with gradual increase in magnitude of load modifier, live load scalar, and resistance bias for both bending and shear effects. However, there is no significant changes in the reliability index for the increase in dead load scalar and the reliability index decreases with an increase in live load bias. This study will facilitate the users of load and resistance factor design specifications such as AASTHO LRFD for understanding the calibration process of load and resistance factor. This will assist the designer to incorporate the local experience and data while designing the reliable structures.
Douglas Nims (Committee Chair)
Luis Mata (Committee Member)
Alex Spivak (Committee Member)
133 p.
Civil Engineering
Structural Reliability; Reinforced Concrete Bridge Girders; T-beam; Reliability Index; Monte Carlo Method; Calibration of Resistance and Load Factors; Reliability Analysis

Recommended Citations

Citations

  • Dallakoti, P. S. (2020). Structural Reliability Study of Highway Bridge Girders Based on AASTHO LRFD Bridge Design Specifications [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1588538610400668

    APA Style (7th edition)

  • Dallakoti, Pramish. Structural Reliability Study of Highway Bridge Girders Based on AASTHO LRFD Bridge Design Specifications. 2020. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1588538610400668.

    MLA Style (8th edition)

  • Dallakoti, Pramish. "Structural Reliability Study of Highway Bridge Girders Based on AASTHO LRFD Bridge Design Specifications." Master's thesis, University of Toledo, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1588538610400668

    Chicago Manual of Style (17th edition)

toledo1588538610400668
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This open access ETD is published by University of Toledo and OhioLINK.