Impact of snow avalanche on buildings: Forces estimation from structural back-analyses

•Structural collapse analysis through simple mechanisms.•Impact pressure estimation after surveys and back-analyses.•Partial building collapses inform about the real event more than total collapses.•Interaction between snow avalanche flow and constructions.•Comparing the results give better estimates about the event.

Snow avalanches, debris-flow and landslides are the major hazards in mountain areas. These phenomena involve high energies and the interaction with urbanized areas often implies large destruction. This is what happened in Italian Alps on December 2008: an avalanche totally destroyed several houses and cut-off the infrastructures (roads, power and telephone lines) for many days.The usual approach to the study of such phenomena considers, first, the setup of a dynamic analysis of the snow avalanche in order to estimate the interaction forces. Following that, the collapse mechanisms are defined and computed. In an opposite way, we herein present a structural back-analysis of the failures of some constructions in order to deduce physical features of the avalanche, most importantly the impact pressures. The need of assumptions on snow characteristics is a great disadvantage for the analysis, meaning that, in the future, accurate measurements on nivological parameters are required.