Serviceability Assessment of Masonry Arch Bridges Using Digital Image Correlation

Serviceability deflections and strains at the crown, support, and quarter point of two aged masonry arch bridges under operating passenger and freight trains were assessed using a digital image correlation method. Three lasers recorded the passage of the wheels; these data were used to ascertain the wheel positions, which corresponded well with the peaks of the deflections measured. The measured maximum deflection and strain were 0.5 mm and 110 microstrain, respectively; these data were validated through a three-dimensional (3D) finite-element model incorporating saturated soil fill, masonry arch, and their interface. The predicted strains matched well with the field measurements. The variation of the strains with the wheel positions over the arch barrel was also simulated. The magnitudes of the deflection and strain were too small to cause serviceability limit-state exceedance alarms for the masonry arches.