Date of Award

Spring 2023

Document Type

Open Access Thesis


Civil and Environmental Engineering

First Advisor

Paul Ziehl


The South Carolina Department of Transportation (SCDOT) is conducting a multi-year effort to load rate its inventory of over 9,400 bridges. This includes many bridges that are load posted due to potential structural considerations (e.g., outdated design loads, members whose capacity is difficult to assess, structural degradation). The number of load-posted bridges in South Carolina is expected to increase significantly due to recent efforts from SCDOT to assess the current state of bridge infrastructure. It is expected that the increased scrutiny may result in more load postings, which in turn may lead to restrictions on truck routes, potential bridge closures, bridge repairs, and in some cases bridge replacement.

Initial findings have identified prestressed concrete skinny leg channels as one superstructure type that has difficulty meeting sufficient load ratings related to flexure. This thesis addresses skinny leg channel girders in their current state and their structural response up to failure to improve load ratings. The primary goal of this thesis is to contribute to the reduction of load restricted bridges in the state of South Carolina. Bridge load postings can be reduced by evaluating structural behavior of channel girders and tailoring load rating strategies to better represent behavior observed in the laboratory. Channels tested in the laboratory proved to be stronger than the nominal capacity, and this is attributed to higher than specified prestressing strand tensile strength and concrete compressive strength. However, some channels resulted in capacities below the nominal capacity, which is attributed to the structural deterioration. Two load rating strategies were investigated and compared: Load and Resistance Factor Rating (LRFR) and Load Factor Rating (LFR). The LFR method proved to be the better method due to its superior performance for strength limit state and service limit state load rating.