DESTRUCTIVE TESTING OF TWO 80-YEAR-OLD TRUSS BRIDGES

Abstract

Two decommissioned 80-year-old steel truss bridges were subjected to a series of nondestructive and destructive tests. The trusses had built-up members that were rigidly connected by rivets at the gusset plates. The floor system, many truss members, and the connections exhibited considerable deterioration. The bridges were retrofitted at critical connections by welding A36 plates on the pre-A7 steel. Both bridges exhibited acceptable performance during the tests at all the limit states. One bridge yielded initially at 371 tons and failed at 415 tons. The other bridge yielded initially at 458 tons, and failure could not be induced under as much as 622 tons because of displacement limits in the loading equipment. The test results revealed that serviceability, damageability, and failure behavior of steel truss bridges possessing built-up members rigidly connected by rivets at the gusset plates are not adversely affected by local deterioration. The built-up members and the connections possessed adequate deformability permitting extensive redistribution. Connection retrofit by welding plates was feasible and successful.