BEARING REPLACEMENT on Glasgow's 'sinking' £8.5M Wing Tower is still on hold as contractor Carillion waits for a weather window that will allow it to begin the tricky operation.
Owner Glasgow Science Centre (GSC) closed the tower nearly four months ago after it discovered the 105m tall structure had subsided 15mm into its 15m deep basement pit (NCE 7 March). Partial failure of a massive thrust bearing at the base of the pit is still seen as the most likely cause of the settlement.
Removal of this bearing, which carries the entire 450t weight of the tower and allows it to rotate through 360infinity, is the first stage of investigating the problem. Jacking facilities were designed into the tower by structural engineer Buro Happold to allow routine bearing replacement, and all the special temporary support steelwork and jacks needed have been installed.
A spokesman for Carillion told NCE that once the bearing had been removed it would be sent away for 'two or three weeks of forensic tests'. The tower would be lowered back down onto the temporary steelwork until such time as a replacement bearing was approved for installation.
Originally it was thought the apparent bearing failure had been caused by corrosion due to water ingress into the basement. Subsequently the possibility of a design or manufacturing fault with the bearing itself was mooted (NCE 14 March).
Carillion claimed it would be safe to reopen the tower while it sits on the temporary steelwork, but a GSC spokesman said no decision had yet been taken.