Public Service Alliance of Canada BC

Via Joy Hennen, Health & Safety Rep on the BC Regional Council

Some interesting earthquake-related information received as a result of an inquiry initiated by the CEIU Regional H&S Committee …

PWGSC funded a series of shake table tests at UBC back in the late 1990’s to test how various office components behave in earthquake scenarios of increasing magnitude. In addition to computer components, bookcases and file cabinets, we also tested the performance of panel hung workstations. Specifically, we tested a Teknion workstation and a Corcan workstation to see whether they would provide adequate coverage for someone doing Drop Cover Hold. Both workstations performed very well.

(The computer-generated events included recreations of the Northridge and Kobe events, as well as “designed” earthquakes of other magnitudes. The simulations also included both lateral and upward thrust motions.)

It was observed that both workstations moved laterally as a result of the lateral motion of the stronger “earthquakes”. As I recall, on one occasion the Corcan unit moved about six inches (it was much heavier than the Teknion, which may have been a factor, but an engineer would be able to provide a more scientific explanation.) The shake table’s deck had been carpeted to recreate a typical office environment, and we surmised that the carpet helped to limit the displacement of the workstations.

It was suggested that in an office environment of several interlocking workstations, the likelihood of lateral displacement would be even further diminished. (There was only room for one workstation at a time on the deck, so this theory was not tested.)

We carefully inspected the workstations after each simulation to see if any workstation components became disconnected, deformed or collapsed. This did not occur in any of the tests, despite increasingly violent upward thrust and lateral movements. Desktops stayed in place, as did hanging drawers and shelves.

We loaded the overhead workstation shelves with typical materials (binders, papers, books, etc.) to see what would happen. Items on open shelves dumped - no surprise there. We also tested bungee chord style restraints to see what would happen. The restraints did not prevent items from dumping - and concluded that they have no value in preventing injury. Lips on the outer edge of an open file did not necessarily prevent items from dumping either - and should not be relied upon to do so. Items stored on enclosed workstation shelves did not dump - but that positive result relies entirely on the occupant keeping the cabinet closed during the workday!

We concluded that panel hung workstations would provide good cover for occupants.

We found that unrestrained file cabinets and book cases taller than three shelves invariably toppled. Where taller furniture cannot be bolted to walls, they should be grouped and bolted together into more stable “footprints”. Heavy objects should be stored in lower shelves. Office equipment should be tethered/strapped to surfaces. And of course, a clear area under the desk should be maintained in which to take cover.

A note about computer components: PWGSC straps its computer screens to work surfaces, and recommends that computer boxes be housed underneath the desk and tethered to the underside of the desktop. However, there are continuous challenges to maintaining these measures. Repairs to equipment, office moves and replacement with new units all result in straps being disconnected. Unfortunately they are almost always left that way. It’s very difficult to keep on top of this problem on an ongoing basis, so once a year an inspection is done to determine what needs to be reattached. Clearly, the onus remains on the individual to know what to do (Drop Cover Hold) no matter what their
immediate circumstances may be. At least in that way, whether potential hazards happen to be restrained or not, the individual will have protection.

(We also looked at whether friction mats placed under equipment would work. We concluded they would not, because they do not address movement caused by the upward thrust of the earthquake.)