Load Distribution and In-Plane Superstructure Movements on Highly Skewed Steel Girder Bridges

Highly skewed girder bridges experience modified load paths, deck diagonal and acute corner cracking, and superstructure horizontal movements caused by long-term loading. This paper presents the instrumentation and load testing of a 23-year-old, three-span, medium-span-length, steel girder bridge with a skew angle of 47° to understand the effects of existing deck cracks on bending and shear girder load distribution. Measured and predicted load distribution factors as per AASHTO LRFD Bridge Design Specifications were compared. Load testing data, consisting of bending and shear strains at multiple locations across the length and width of an exterior span, were used to validate finite element models. Bridge models under temperature loading were used to evaluate the importance of bridge skew angle on in-plane superstructure displacements. The investigation showed that skew had a major role in bridge in-plane displacements, and consequent superstructure in-plane rotation, leading to greater transverse displacements with increasing skews under thermal loading.