State Bridge Load-Rating Program

This project compiled and summarized the results of the American Association of State Highway and Transportation Officials’s Virtis load-rating software program utilized by Benesch for the load rating of a number of state-system bridges throughout Missouri. The project consisted of nearly 150 structures categorized as one of six bridge types: reinforced concrete slabs, reinforced concrete deck girders, prestressed bulb-tees, prestressed I-girders, simple span steel girders and continuous steel girders.

The Missouri Department of Transportation (MoDOT) supplied existing bridge plans, available National Bridge Inventory (NBI) information and a summary of existing conditions for each of the 150 structures. Ultimately, a summary report provided information on modeling techniques in order to benefit future Virtis users. Comments and suggestions were provided for modeling each bridge and included common modeling mistakes, flaws, or areas of concern found in the program and other details.

Benesch performed a load rating analysis for each bridge within the Virtis program and provided quality assurance checks to verify that the data entered into the software was correct. The Virtis load ratings were then compared to existing MoBARS load ratings to validate the results, determine the source of discrepancies between results, and provide explanations if possible.

The project team tracked the time required for data input and load-rating analysis for each individual bridge, and MoDOT was provided with an electronic file of completed structures.