Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Civil Engineering

Committee Chair

Robert J. Connor

Committee Co-Chair

Amit H. Varma

Committee Member 1

Mark D. Bowman

Committee Member 2

Karl H. Frank

Committee Member 3

Brian M. Kozy


High torsional rigidity and attractive aesthetics in construction of twin-tub-girder bridges make them preferable for the design of curved bridges. However, according to the concepts associated with the term “Fracture Critical (FC)” that are in place today, all two-girder bridges are always classified as having FC members. For a steel bridge with FC members, the fracture of any of its members may result in complete catastrophic failure or significant loss of serviceability; hence, every two years twin-tub-girder bridges are subjected to very expensive hands-on field inspection. Full-scale simple span twin-tub-girder bridge tests at University of Texas Austin have demonstrated excessive load capacity of a fractured simple span bridge. A significant number of twin-tub-girder bridges might be classified as redundant; however, this individual test is not adequate to define the comprehensive damage behavior of twin-tub-girder bridges in general. In this dissertation, 3D non-linear (material and geometric) detailed finite element (FE) analysis procedures which have been calibrated from full-scale testing providing confidence in the results were developed. The FE models included all the plastic and damage behavior of reinforced concrete deck, brace connections, all steel components of the super structure, stages of construction, and the effects of the dynamic amplification of the bridge immediately following the fracture. Detail work was also performed to define comprehensive shear stud behavior.