huangyhg

existing building drift
are there any instruments available to measure the drift of an existing building under wind loads?
a plumb bob placed in an elevator shaft may give you what you want.
yes. one easy way is to use an inclinometer hooked to a recording device. this will allow you to catch peaks and to coordinate precise correlation with the wind load. ideally you would set up at least two inclinometers (two orthogonal directions), one digital anemometer, and several strain gages...all fed into one multi-channel data acquisition system. this allows real-time monitoring, the features and anomalies of which can be overlaid on a single time scale to develop correlations.
setups like this have been used in determining movements and stresses for blast or demolition operations (dropping a building in congested urban setting) as well as the recent, highly sensitive moving of the cape hatteras light house.
gps instruments are now common. i am not sure they are accurate to the closest inch. feet yes but maybe the better quality one can give outputs to higher accuracy. the trouble with plumb bobs is that they tend to move with the building mount , are very awkward and dangerous to record. multi plex is usually technically tricky and not cheap.triangulation with ground targets and cheap ruby lasers ( laser carpentry levels ). best. cfpeng.

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