The second talk Friday was Michael Scott talking about how Oregon rates the safety of highway bridges.

Rating is done to compare the bridge capacity with demand imposed by vehicles. Large number of diagonally-cracked bridges exist (fatigue, corrosion; reduction in capacity). Purpose of assessment: vehicle weight restriction and prioritization for repair.

- Identify potential critical locations on each girder of bridge
- calculate capacity at each location from bridge design drawings
- Calculate moment and sheer demands at each location for suite of rating vehicles
- Calculate the rating index to indicate probability of demand exceeding capacity

Tcl extension built to make use of OpenSees, an open-source software framework for computational models and solution algorithms for finite element analysis of structural systems developed at Berekely.

Tcl fully programmable, thus suited to repetitive nature of moving load
analysis. Showed some example scripts (`foreach truck $truckLibrary { ... }`). Calculates a statistical rating for each bridge. Can graph rating
index at all critical locations for each bridge. Makes it possible
to do targeted repairs.

Future enhancements:

- Apply methodology to other bridge types
- 3D bridge model
- Mult-hazard rating (earthquake, corrosion)
- Network-based testing and simulation as part of NEES
- Pre- and post-processor using Fox

Thanks to Oregon Department of Transportation for sponsoring this research.

—Michael A. Cleverly

Friday, October 13, 2006 at 09:04