In-Service Analytical Investigation of Precast-Concrete,Short-Span,Skewed Bridges with Integral Abutment Walls

Abstract

Precast-concrete, skewed bridges with integral abutment walls are typically designed as simplified two-dimensional rigid portal frames, neglecting the degrading effects of the skew angle and laterally unsymmetrical vertical loading. This practice produces under-designed bridges for certain aspect ratios, causing cracking and local deterioration near the obtuse corners of the deck. To evaluate the limitations of this practice, an analytical study was carried out for the live load response at the linear service level. Three-dimensional finite-element models of precast-concrete, short-span, skewed bridges with integral abutment walls were developed and analyzed. For some bridge configurations, both the positive and negative moment stresses are higher than the stresses given by simplified two-dimensional frame analysis. In other cases, the two-dimensional frame method results in over-designed bridges. The results were presented in correlation diagrams, enabling simple comparison and quantification. The correlation diagrams also provide modification factors to amend the simplified two-dimensional frame design.

Keywords

bridges finite-element analysis integral abutments precast concrete skewed bridges frame analysis

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