Development and Applications of Mechanics- and Data-based Capacity Models for Intact/Corroded Prestressed Concrete Bridge Girders
Creators: Liu, Jiadaren
Publisher: name: University of Alberta Library
Year: 2022

<p>Prestressed concrete (PC) highway bridges represent an integral part of the transportation network and contribute significantly to socio-economic development. However, highway bridges are susceptible to Deterioration and thus exhibit structural deficiency after years of service, especially in the cold climate of North America (e.g., Alberta, Canada) where the de-icing salt is used seasonally and can heavily corrode roads and bridges. To facilitate the reliability-based safety assessment for both intact (e.g., as-built) and corroded PC bridge girders, reliable load-carrying capacity prediction models are required as a fundamental ingredient including both mechanics-based and data-based models. <br>
Firstly, a mechanics-based load-carrying capacity prediction model (i.e., a flexure-shear coupled fibre beam element) for intact PC girders was developed based on Timoshenko beam theory combined with multi-axial material models, as complementary to the conventional fibre beam elements without considering shear. The developed element was validated through a classic test series of shear-critical reinforced concrete (RC) beams from the literature and a PC girder recently tested under both shear-critical and flexure-dominated scenarios. Then, the developed element was applied to a representative nine-girder PC bridge in Alberta, Canada to study the bridge system behavior and load sharing of multi-girder bridges.<br>
Data-based shear capacity models for intact PC girders were then developed by adding probabilistic correction terms to existing deterministic design code models. In this research task, an experimental database containing 369 PC girders that failed in shear was compiled. Using the experimental database, shear capacity models from five concrete structure and bridge design codes were assessed, including ACI 318-19, AASHTO LRFD 2017, CSA A23.3:19, CSA S6:19 and fib MC 2010. Probabilistic correction terms were then calibrated and added to the design code models via Bayesian linear regression and Gaussian process regression approaches. The resulted models can benefit shear capacity predictions with better accuracy and precision, as well as reliability/fragility analysis of PC girders with the model error considered.<br>
Data-based load-carrying capacity models were also developed for corroded PC voided girders which are popular for short-span bridges in North America. Firstly, a 2D continuum-based FE model for corroded PC girders was developed and validated by existing experimental tests. Then, a virtual experimental database of 4,165 PC girder tests considering various design, loading, and corrosion conditions was generated based on the developed FE model. With the generated virtual experimental database, the probabilistic capacity reduction factor model and the load-carrying capacity model were developed via Gaussian process regression to study the corrosion effects on capacity reduction and failure probability of corroded PC girders, respectively.</p>