The Structural Analysis, Design, and Prototype Testing of Three-Sided Small-Span Skewed Bridges

An analytical study was carried out for the structural performance assessment of precast-concrete, short-span, skewed bridges with integral abutment walls. Typically, these structures are designed as simplified two-dimensional rigid portal frames, neglecting the degrading effects of the skew angle and laterally unsymmetrical vertical loading. This design practice produces under-designed bridges for certain aspect ratios, causing cracking and local deterioration symptoms, observed in some instances out in the field. To evaluate the limitations of this practice, three-dimensional finite-element models were developed and analyzed. Accordingly, these finite-element models simulate various geometric configuration parameters, as well as, laterally symmetrical and unsymmetrical vertical load conditions, capturing the amplification of the structural response. Field-testing was also performed on a bridge to substantiate and calibrate the finite-element results. The results of the simplified plane frame analyses and three-dimensional finite-element analyses were presented in correlation diagrams, enabling simple comparison and quantification. The correlation diagrams provide correction factors to amend the simple frame design. The response observations offer a qualitative insight into the actual behavior of the structure, allowing the performance assessment of existing bridges of the same type and a more reliable design in the future.