Optical 3-dimensional measurements on a FRP beam tested at serviceability limit

Optical stereoscopic measurements were performed on a real size 14 m long fibre-reinforced polymer composite vehicular beam bridge submitted to four-point bending. The field of view was 6 m, with a pixel resolution of ∼4 mm. The 3-D displacements were monitored by targets and texture tracking. Optical measurements show good correlation with traditional sensors. They allowed measuring 3-D displacement and strain fields, evidencing the out-of-plane buckling displacement of the beam web, sensing unforeseen displacements and giving insight in the boundary conditions of the experiment.