Health assessment of concrete dams by overall inverse analyses and neural networks

In several existing dams alcali-silica reaction (ASR) during several decades of service life, or diffused micro-cracking (due to concrete ageing and/or past extreme loads, such as earthquakes) give rise to deterioration of concrete stiffness and to correlated reduction of its strength. An inverse methodology is presented herein apt to identify damage in concrete dams on the basis of hydrostatic loading, measurements by traditional monitoring instruments, such as pendulums and collimators, and artificial neural networks trained by means of finite-element simulations. The arch-gravity dam referred to in this study is sub-divided into homogeneous zones, to which a constant Young modulus is attributed as unknown parameter which quantifies possible damage. These elastic moduli are estimated on the basis of pseudo-experimental data and identification procedures. After a suitable 'training' process, artificial neural networks (ANNs) are employed for numerical solutions of the inverse problem, and their potentialities and limitations are examined to the present purposes. In particular, they turn out to be robust and practically useful in the presence of information which are scarce quantitatively (few available measurements) and/or qualitatively (large noise-to-signal ratio).