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Show magnitude of the force neces shove the house after liftin only about 15 tons was suffi rear surface of the building Blons and Sonntag show first fective forces, and second, actions which nevertheless o upward directed components o preventive measures are take these ( upward) forces. sary to break the roof beams from below, while to g ( with a coefficient of friction on snow u ~ 0.2) cient, which corresponds to about 800 kg/ m2 on the The estimated calculation of the two cases in , satisfactory agreement in the magnitude of the ef-relatively small forces. The severe destructive ccurred are attributed primarily to the action of f force on the houses. Normally no constructional n in the usual residential structures to absorb TABLE 1 Principal Data on the Destroyed Houses ( Data are approximate) Width Length Height of first story Height of gable wall Wall thickness ( without shingles) Roof area Weight, estimated Force to raise one side including the snow load Upward thrust per square meter of wall meters meters meters meters centimeters square meters metric tons metric tons kg/ m'< House in Blons 6 8 2.5 4 17- 18 100 40- 50 20- 25 650- 750 House in Sonntag 10 10 2.5 4 16 180 60- 70 30- 35 700- 800 Trummer yon der Ruchseite des hauses Fig. 6. Schematic representation of the destruction process of houses in Blons ( Fig. 4) and Sonntag ( Fig. 5) before and after the catastrophe. Lawine - avalanche, Fundament intakt -- foundation intact, Trummer von der Ruckseite des Hauses - Debris from the back side of the house. c) House and Stable " Walkenbach" The house was of frame construction and was built deep in the slope, so that the gable wall on the mountain side rose only 2 or 3 meters over the ground. Timbers of a stable located higher had been carried onto the roof by an avalanche; furthermore, the structure of a cable railway station located immediately nearby was torn away. In spite of the light construction, the house sustained no external damages worthy of mention except for a small displacement towards |