Aceña dam Massimo Meghella*, Piero Masarati* Ninth International Benchmark Workshop on Numerical Analysis of DAMS San Pietroburgo, Russia 22-24 Giugno 2007 * CESI RICERCA In the frame of the ICOLD -9thBenchmark Workshop on Numerical Analysis of Dams, the proposed Theme A on the” Analysis of the elastic behaviour of an arch-gravity dam” has been approached by using CANT-SD, a FEM code developed by CESI RICERCA for the structural analysis of dams. Due to the information incompleteness about the actual thermal boundary conditions (no reservoir temperatures are available) and the insufficient knowledge of the measured behaviour (block 3 plumbline measurements only), several analyses have been carried out in order to investigate both the influence of each single load component and of the materials parameters on the observed behaviour. In addition , a system identification process aimed at modelling the external temperature conditions to apply to the upstream/downstream faces of the FEM model of the dam in order to simulate the measured behaviour has been attempted. Finally, through a suitable combination of each single load component with a properly calibrated set of elastic parameters and boundary temperature conditions a possible interpretation of the measured structural behaviour has been provided.