Bridge Structural Evaluation – Live Load Testing & Load Rating

BDI was contracted to perform NDE, structural evaluation, and live load testing on a private access bridge. BDI’s scope of work on this project included: making onsite measurements; determine wood species; performing load tests and data collection; completing a thorough investigation of the structure; creating a field-verified analytical finite-element (FE) model; and calculating load ratings for the AASHTO standard rating vehicles and client-specified rig vehicles. Prior to this project there were no inspection or load capacity records.

The structure was instrumented with 37 strain and 12 deflection sensors, and controlled load tests were performed with an 80-barrel water truck. A finite element model of the structure was developed and modified until an acceptable match between the measured and analytical responses was achieved. This field-verified model was then used to analyze the responses of standard AASHTO vehicles and client-specified rig vehicle configurations. Load ratings (based on Larch Fir No. 2 grading) were then performed to identify the permissible axle weights of the rigs. While the controlling load rating component was flexure at mid-span, the worst-case client rig produced a rating factor of 1.03.

BDI mobilized a crew to a remote location along with our subcontractor in a short time frame to meet the client’s timeline for moving oil rig gear from one site to another. Field data was successfully collected while having to adapt to unknown conditions in one filed day. The analysis and subsequent report were completed on time for the client allowing them to maintain their construction schedule.