Date of Award


Publication Type

Doctoral Thesis

Degree Name



Civil and Environmental Engineering

First Advisor

Ghrib, Dr. Faouzi

Second Advisor

Sennah, Dr. Khaled




The concept of load distribution factors have been used in bridge design for many decades as a simplified method to estimate load effects on bridge members. It enables bridge engineers to consider the transverse and longitudinal effects of truck wheel loads as two separate phenomena and thus simplifying the analysis and design of new bridges as well as for the evaluation of the load carrying capacity of existing bridges. Existing bridge design codes do not provide sufficient guidance to bridge engineers regarding the accurate assessment of load distribution factors for skew composite bridges. Thus leads to an extremely conservative design in some cases and to unsafe design in others, since these factors do not represent the actual behavior of the bridge structure. The presence of skew angle makes the analysis and design of composite slab-on-girder bridges much more complex in comparison to straight bridges. Over the past decade, several authors have drawn attention toward the steel I-girder twisting placed over highly skewed supports. These rotations are larger at the obtuse corners and difficult to predict due to the uneven load distribution across the bridge superstructure. In addition to girder twisting, skewed bridges can also lead to increased lateral flange bending stresses as well as increased shear and end reactions at girder obtuse corners that subsequently results in the reduction of girder shear and end reactions, and even possibly undesirable uplift in girders at the acute corners of the bridge.