|Customer:||Bernhard Bieri Architects|
|Report:||090718, 18. Juli 2009|
Before intensive construction activites began in the close vicinity of his building, the owner of the 200-years-old Building „Zum Wöschhuus“ in Stallikon had initiated a detailed investigation into the actual state-of-health of his building. In addition he had asked for a longterm monitoing campaign of the vibrations of the structure. The first was performed by Corak Engineering, Zürich, the latter through rci dynamics.
Two 3D geophones GSV 320 and GCR-16 data acquisition units were installed in this building and the vibrations monitored from October 15, 2008 to April 17, 2009. One of the monitoring stations was located in the cellar the other one on the third floor.
The vibrational velocity measured on the third floor was usually smaller than the mutually agreed limiting value, v = 10 mm/s. The graph below shows the development of the maximum-per-minute velocity value in the X, Y, and Z directions as well as the corresponding vectorial sum value over 24 hours (1’440 values) for a „normal“ working day .
The limiting velocity value was surpassed in two cases in October 2008 and in March 2009 respectively. In such a case, an SMS alarm is sent out and the maximum-per-minute (permanent recording) scheme is supplemented with a 30 seconds high-frequency (event recording) signal acquisition (see below). With v = 18 mm/s this violation was quite significant in one of the two cases mentioned. Since the two cases were quite singular no general measures like interruption of the construction activities were taken.