Dynamic movement of the Humber Bridge rocker bearings
Tuesday, May 15, 2012 at 4:53PM Arup, working for the Humber Bridge Board, wanted to know whether the rocker bearings at the Humber Bridge were moving appropriately, which meant detecting 0.3mm of movement at a radius of about 200mm. The Moiré Tell Tale was attached at the location shown in the diagram below, the white part bent to a right angle to attach it to one part of the bearing and the transparent overlay attached to the other.
The Moiré Tell Tale was then filmed. This video is accelerated, showing about 3 minutes worth of movement in 30 seconds.
John Collins of Arup said, “The tell-tale immediately gave useful results. A 0.3 mm displacement took place over 9 seconds. This rate of movement simply cannot be observed with the naked eye and is difficult to detect (and un-quantifiable) by touch.”