Damage Assessment of a Two-span Model Masonry Arch Bridge

A scaled model of a two-span masonry arch bridge has been built in order to investigate the effect of the central pile settlement due to riverbank erosion. The bridge geometry and the structural details, included the masonry bricks and mortar joints, are realized in the scale 1:2. The model bridge has been equipped with different Non Destructive Testing (NDT) instruments, including accelerometers, displacement transducers LVTD, strain gages, optic fibres strain sensors and Acoustic Emissions (AE). The model bridge will be subjected to incremental settlement of the pile, which was sustained on a mobile support. In the present paper a detailed description of the numerical simulation of damage localization is reported. The results allow for an estimate of the most damaged zones, where measurement instruments should optimally be placed. In addition, information is provided concerning the basic modal features of the bridge, including the principal natural vibration modes and frequencies. The dynamic analysis is performed also subsequently, in order to assess the natural frequency shift and to guide the instrumental setting for damage identification. In the prosecution of the test, thanks to the use of six AE piezoelectric transducers, it will be possible not only to detect the ultrasonic emissions, which are due to the propagation of cracks, but also to locate the damage sources. Those results will be compared with the numerical simulations, and will be exploited for the model updating. Useful criteria for the interpretation of real structure cracking and for the assessment in presence of riverbank erosion phenomena are expected.