Affiliations: Civil Engineering Department, University of New Hampshire, Durham, NH, USA
Note: [] Corresponding author. Erin Santini-Bell, Civil Engineering Department, University of New Hampshire, Durham, NH, USA. E-mail: erin.bell@unh.edu
Abstract: Bridge owners, especially municipalities, are becoming overwhelmed with increasing maintenance costs and decreasing maintenance budgets. Limited available funds require that each maintenance dollar be efficiently allocated to the most critical bridge structure. Objectively determining the most critical bridge structure often requires nondestructive evaluation and testing, which can be costly in terms of equipment, traffic delay and personnel, all of which impact a limited transportation budget. The installation of traditional sensors, which typically need to be in physical contact with the bridge, can require special equipment for access to key bridge elements as well as wiring for power supply and data acquisition. Digital image correlation (DIC) can be used as an alternative to traditional bridge response measurement instruments such as strain gages or linear variable differential transformers, commonly referred to as LVDTs. DIC is an optical measurement technique that has the ability to capture displacement data in both two and three dimensions through high-resolution digital photography. Because it is a non-contact, nondestructive means of measuring bridge responses, it is an attractive choice for rapid testing of in-service structures. Researchers at the University of New Hampshire have conducted a series of laboratory and field experiments for verification of DIC application for civil structures in which the DIC system and LVDTs recorded displacement data simultaneously. Upon comparison, the two methods showed nearly identical results, with the DIC within 0.03 mm of LVDTs. With a high confidence in DIC, the field-collected deflection data was used to verify design and analytical structural models of two tested bridges; a newly constructed three span continuous steel girder bridge and a short concrete slab culvert with a fiber reinforced polymer reinforcement retrofit. The collected DIC measurements were used for model verification and evaluation of the innovative retrofit program, respectively. Results from both field tests are presented in this paper. The ability to capture a bridge's behavior with DIC and calibrate a structural model with the collected data provides bridge designers and managers with an easy-to-collect objective measure of bridge performance.
Keywords: Structural health monitoring, bridges, deflection, digital image correlation, modeling, non-destructive testing
