Effects of Skew Angle on Simple Span Bridge Decks under Simulated Truck Loading

摘要

The finite element method was used to examine effects of skew angle on the major principal moments of simple spans. A mesh size of eight span elements in 30 ft was found to give results within about 6% of those found from a more intricate localized mesh surrounding a more realistic tire load. These results varied little with change in aspect ratio. This mesh size was therefore chosen as a guide for the parameter studies which followed. Skew angles of 0, 20 and 40 deg were investigated for various width to span ratios (WSR's). The major principal moments at key points in the deck were examined as an FDOT SU-4 type truck was moved across the span. The service load simulator program was used to calculate the equivalent nodal forces for the truck in any position on the skewed deck. Results showed that for center loading, peak moment reductions of up to 24% were found for 40 deg skew decks over orthogonal decks; percent reductions were lower for smaller WSR's. In general, the major principal moments peaked earlier (i.e., at lesser advanced positions of the truck along the span) for increased angles of skew. This can be attributed to the fact that the wheels of the axles do not reach span center simultaneously. The direction of reinforcement plays an important role in the flexural behavior of the deck. Skewed reinforcement is the preferred method from the construction point of view.