Analysis of preservice cracking in a large bridge structure

Abstract The failure of a structure to perform its intended purpose is normally detected after some period of service, but sometimes cracking or other difficulties are discovered during preservice inspection. This is illustrated in the cracking discovered in the Luling Bridge, a cable-stayed box-girder structure located near New Orleans, Louisiana, prior to its opening. Visual inspection of the box members indicated cracking in a variety of welded connections. An extensive investigation using polished and etched core samples subsequently identified the two main causes for the cracking phenomena: fatigue cracking from cyclic stresses during shipment, and cracking associated with weld discontinuities. Based on this information, hole drilling to remove existing and potential defects was determined to be an adequate remedial action and allowed the bridge to enter its intended service with minimal delay.