Deflection distribution estimation of tied-arch bridges using long-gauge strain measurements

Deflection, as a critical indicator for structural performance evaluation, is difficult to be measured accurately for long-span bridges, though various deformation sensors and devices have been developed. In this paper, a new scheme using long-gauge fiber optic sensors for estimating the deflection distribution of tied-arch bridges is proposed. First, the complex strain state of the tied-arch bridge is investigated, in which a cubic function describing the axial strain distribution of the tie beam is obtained. Second, the bending strain is separated from the measured long-gauge strain which is a combination of axial and bending components by a sensor layout scheme. Finally, the separated bending strain is utilized to estimate the deflection distribution of the tied-arch bridge through an improved conjugate beam method. Numerical and experimental examples are studied to illustrate the effectiveness of the proposed method for deflection estimation of tied-arch bridges in static and dynamic loading cases.