The Bayou Pierre bridge in Louisiana has five equal spans with a total length of 500 ft. The superstructure consists of 10 PPC girders, and the substructure consists of reinforced concrete caps and steel piles. The 10,000 kips (4,500 tons) DRAGLINE crossed the bridge under continuous monitoring using 46-axles SPMT, taking 85 minutes.
SDR was tasked to evaluate the strength of the bridge to withstand DRAGLINE loads, to instrument and load test the bridge before the DRAGLINE crossing, to continuously monitor the bridge during crossing, and to carry out hands-on inspection of all bridge elements after crossing.
3-D numerical models, including soil-structure interaction, were developed to estimate internal forces on the bridge elements under the weight of the DRAGLINE and transporters. The bridge was instrumented using linear variable differential transformers (LVDTs) and strain gauges. The diagnostic test loading was applied using a combination of counterweights and six 390-kip trucks to fully load two adjacent spans. Load testing included verifying the piles’ capacity, potential settlement, and residual settlement.
Results from analyses and testing determined the safe passing weight from 10,000 kips to 8,300 kips. Hands-on inspection of bridge following the crossing indicated excellent conditions of the bridge
