Date of Award


Degree Type


Degree Name

Master of Science (MS)


Civil and Environmental Engineering

Committee Chair(s)

Marc Maguire


Marc Maguire


Andrew Sorensen


Joseph Caliendo


The bridge being studied spans the Black Slough River in the Nucor/Vulcraft facilities near Brigham City, Utah. The bridge is composed of seven heavyweight open web steel joists supporting a concrete deck-slab element and sitting in two concrete cantilever walls serving as bearings. A full-scale live-load test was performed using forklift vehicles at four locations on the deck. During the test, axial strains, deflections, and rotations where measured.

In their provisions, the American Association of State Highway and Transportation Officials (AASHTO) included a simplified number of equations and solutions used to calculate GDFs for standardized decks supported by beam systems. Due to the nonexistence of records for bridges with open web steel joists as deck supporting systems, a number of (AASHTO) GDFs were analyzed and compared to live-load test results to determine which system best mimics this unique bridge live load distribution. Three analysis approaches were also performed to compare their results to the experimental and AASHTO GDFs. In addition, a finite element model (FEM) for this bridge was made by a team of researchers from Kansas University in conjunction with this study. This model was also included in the final methodology comparisons.

The AASHTO calculated GDFs were significantly larger than the measured; on the other hand, the other methods analyzed provided a more accurate prediction of each beam girder distribution factor, following the recorded GDFs trend. The best method was chosen and further theoretical calibration suggestions were made for prediction of the behavior of this bridge using FEA.