Acoustic Emission Monitoring of Prestressed Girders during Fabrication and Transport

Prefabricated and prestressed, reinforced concrete girders used as prefabricated bridge elements and systems (PBES) are common in infrastructure projects. Concerns exist that fabrication and transport processes can cause cracks in the girders prior to service use. Acoustic emission (AE) sensing is a nondestructive testing (NDT) technique that records transient elastic waves produced by damage processes, such as crack nucleation and propagation. This paper presents AE data collection and analysis during detensioning, lifting, and transport of full-scale straight and hammerhead (haunch) Northeast bulb-tee (NEBT) girders. This study found that horizontal web cracks nucleate during detensioning and the use of b-value analysis threshold can assist in predicting the occurrence of cracks. In addition, transport of hammerhead girders produced the largest number count of AE events and may be explained by the reverse loading moment of the girder during transport compared to the nominal in-service state. Keywords: accelerated bridge construction; acoustic emission; craned lifting; detensioning; nondestructive testing; Northeast bulb-tee; prefabricated bridge elements and systems; prestressed concrete; transport.