Improving Bridge Rating and Truck Permitting Procedures Through Finite Element Analysis

D. S. McIlrath, K. H. Frank, S. L. Wood, and J. A. Yura


Annually, state DOTs are confronted with thousands of overweight truck permit applications and must determine the ability of bridges along these routes to carry the permit loads. This research shows the benefits of performing more detailed analyses using SAP2000 and BRUFEM, rather than using the AASHTO empirical equations, which were developed based upon bridge behavior under design loads. Using these programs, lateral load distribution factors are more accurately calculated, giving better estimates of the actual stress levels in bridge elements. Procedures are discussed, and research results shown, to help an analyst determine which types of trucks will be likely to cause damage to various bridge designs. Implementation suggestions for the efficient office use of these computer programs are also discussed. Use of these programs will allow state DOTs to model the response and stress levels within bridge structures more accurately, allowing for longer bridge service lives in most cases.

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