Pressure‐activated adhesive tape pattern for monitoring the structural condition of steel bridges via digital image correlation

Abstract

Digital image correlation (DIC)—a photographic measurement technique that relies on pattern recognition to calculate displacements and strains—can provide unprecedented data on bridge behavior, strength, and overall condition. A major challenge in using DIC to measure full-field strains and displacements (as opposed to point tracking) in bridges is applying an appropriate stochastic pattern over the entire field of view as conventional strategies (e.g., spray paint) are time-intensive to apply. For steel bridges, in which members are treated with a protective multilayer paint coating, the pattern must also be applied without removing the protective coating system and be compatible with the coating system such that it follows the strain in the steel. This paper investigates pressure-activated adhesive tape as a strategy to rapidly apply a stochastic pattern for full-field monitoring of steel bridges. A stochastic pattern, designed for minimal noise in DIC measurements, can be generated electronically and printed on the tape prior to tape installation. This paper investigates tape as a pattern strategy by performing tensile tests on bare and coated steel samples. Measured DIC results using tape patterning are compared with readings from conventional instrumentation (i.e., strain gauges and extensometer) and DIC measurements using spray paint patterning, as well as finite element predictions. The results clearly indicate that the pressure-activated adhesive tape follows the strain in both bare and coated steel and affords a viable patterning approach to implement DIC in monitoring and assessing steel bridges.