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Show b) Dwelling House in Sonntag ( Figure 5; Table 1) The construction of the house was practically the same as that of the Mesmer house in Blons; the gradient of the avalanche path was probably somewhat less. In contrast to the house in Blons, here the lower part of the back wall was significantly less destroyed than the gable wall and the rear half of the roof. The cause was a large log pile situated behind the house, which protected the middle part of the lower back wall and acted as a deflecting wedge. Although the entire house was moved forward about 7 meters, the wood pile moved forward only about 1 meter in the upper part, which indicates a relatively smaller horizontal pushing action in this situation. The length of the snow wedge accumulated against the wood pile still amounted to about 7 meters at the time of inspection, when considerable settlement already had occurred. Sa Fig. 5. House in Sonntag Left: Portion of the front structure pushed and tipped forward. In the Center: Portion of the side wall of the rear part of the structure with lifted and thrown off timbers. The beam over the window is also raised. Right: Detail of the rear corner showing mortise- and- tenon joint lifted apart., The destruction of the gable wall is not attributed to bending failures of the timbers. As Figure 5 shows, the logs were torn apart by a vertical, upward acting force. A force of similar direction destroyed the roof beams. The fragments were still lying in the immediate vicinity of the structure and permit one to conclude neither an impact action nor a large velocity of the pushing snow. In the zone where the roof was destroyed, the floor of the top story, 5 meters by 4 meters consisting of fir planks 40 mm thick, was bent trough- like to the breaking point, where the mass of snow was evidently dammed up until the roof was destroyed. The calculated static load to make an indentation on the floor of the top story amounts to 300 to 350 kg/ m2. From these observations it follows that, in time sequence, first, because of a vertical upward component of force the gable wall and a part of the roof were destroyed and the entire structure was raised at the rear from the foundation, and then in a later phase, the whole house slid forward because of the dammed up mass of snow. To raise the house on one side a vertical force of about 30 to 35 tons ( approximately 0.7 tons/ m2 on the facade surface) was necessary, which corresponds to the order of |
