New Method for Estimating Wave Forces on Bridge Decks
A new method for estimating wave loads on bridge decks was developed as part of this study. The new method is an adaptation of some of the existing guidance (primarily McConnell, et al. 2004) for the typical U.S. highway bridge geometry. The new method is relatively simple, can be applied conservatively, and can be modified based on future laboratory findings. Wave loads are assumed to be proportional to a form of “hydrostatic” pressure as measured from the crest of the largest waves in the design sea-state.
I-10 Ramp near Mobile, AL
he new method does a good job of explaining the damage to bridges in Hurricanes Katrina and Ivan. Estimated wave loads are sufficient to overcome the weight and connection resistance for the spans at lower elevations that failed (moved) at three bridges:
- the I-10 bridge across Escambia Bay, Florida;
- the I-10 on ramp near Mobile, Alabama; and
- the U.S. 90 bridge across Biloxi Bay, Mississippi.
Estimated wave loads are not sufficient, however, to overcome the weight and connection resistance for the spans at higher elevations that did not fail.
The new method is recommended as interim guidance until it can be replaced or modified as new research addresses some of the important questions more comprehensively.