Bridges, Tunnels and other Transportation Structures
The Governor Mario M. Cuomo Bridge - a twin span cable-stayed bridge – is being constructed to replace the Tappan Zee Bridge over the Hudson River. The strains induced during erection of the Eastbound cable-stayed span have been monitored using three-dimensional digital image correlation (DIC). This presentation will demonstrate the implementation of DIC to measure erection-induced strains and will present the measured strain distributions induced in the North and South edge girders due to cable anchorage. The authors are grateful to the New York State Thruway Authority for providing the opportunity to perform this research and facilitating the field implementation.
DIC is a non-contact, photographic method that measures strain and displacement based on pattern recognition and photogrammetric triangulation principles. More specifically, DIC photographs of a measurement region are taken before and after loading. A random black and white pattern needs to be applied to this measurement region prior to taking these photographs. DIC software then uses a correlation algorithm to match the same locations in the series of photographs and calculates strains based on the movement of the same region (Schmidt et al 2003a).
DIC offers many advantages compared to conventional instrumentation (e.g., strain gages). Since the entire patterned region can be tracked, a full-field strain map can be generated and system behavior can be studied. The direction of strain measurement can also be varied in post-processing. Wires and an on-site data acquisition system are not needed. This feature makes DIC uniquely suited to be able to measure erection-induced strains as construction practices would typically prohibit wiring and continuous data collection. Instead, DIC photographs can be taken at varying stages of construction to measure the strains induced due to various procedures. While there is prior research in using DIC to monitor bridges [e.g., Wang et al. (2018), Nonis et al. (2013), Bell et al. (2012)], this is the first implementation of DIC to measure erection-induced strains in a bridge.
This presentation will introduce DIC as a powerful tool for measuring erection-induced strains. The measured strain distributions due to cable anchoring of the North and South edge girders of the Governor Mario M. Cuomo Bridge will be presented and the behavior will be discussed. Recommendations for field implementation of DIC will also be given to help the audience use this new technology.
Bell, E.S., Peddle, J.T., and Goudreau, A. (2012) “Bridge Condition Assessment using Digital Image Correlation and Structural Modeling.” Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management, 165(4), 330-337.
Nonis, C., Niezrecki, C., Yu, T.-Y., Ahmed, S., Su, C.-F., and Schmidt, T. (2013) “Structural Health Monitoring of Bridges using Digital Image Correlation.” Proceedings of the SPIE – The International Society for Optical Engineering, 869507.
Schmidt, T., Tyson, J., and Galanous, K. (2003) “Full-field Dynamic Displacement and Strain Measurement using Advanced 3D Image Correlation Photogrammetry: Part I.” Experimental Techniques, 27(3): 47-50.
Wang, Y. Thrall, A.P., and Zoli, T.P. (2018) “Delaware River Bridge Fracture: Repair Strategy and Monitoring by Digital Image Correlation.” Proceedings of the World Steel Bridge Symposium.