In California, it seems the latest way for engineering teams to simulate what happens to buildings and equipment inside them in an earthquake is to literally subject a real five-storey building packed with medical gear to the same motions they would experience through such disasters.
In Canada, the latest way is somewhat less intense. In fact, it involves using a recently upgraded version of a technology which dates back, in one form or another, more than a century: shake tables.
Common throughout the US, Europe and many parts of Asia, shake tables test buildings or structures under simulated earthquake conditions, typically by fixing structural models or building components to a rectangular platform that is driven by up to six degrees of freedom by servo-hydraulic or other types of actuators.
On display recently at the University of British Columbia (UBC), however, was a new multi-directional shake table – the first of its kind in Canada.
Unlike traditional shake tables, which involve shifting the table using side to side movements only, multi-directional tables involve movements in multiple directions, providing tests which more closely simulate actual earthquake conditions.
The model on display at UBC was completed last year.
Carlos Ventura, director of UBC’s Earthquake Engineering Research Facility, is excited about the potential uses for the new table, which he says include seeing how models of buildings react under a range of different shake related conditions and testing how individual building components, such as walls, react to the shaking.
With the current popularity of retrofitting existing buildings, the tables can easily be used to test whether or not retrofitted components work as expected.
“[The shake table is] being used to develop retrofit strategies”, Ventura is quoted as saying in a recent article in the Vancouver Courier. “We develop some ideas of what we think will be a low-cost retrofit and then, before that way of strengthening the building [is accepted], we construct a model and we put it on the shake table, shake it, and do different experiments. That allows us to confirm the theory.”
Seismic Upgrades for Schools
The demonstration followed a May 11 press conference in which Education Minister George Abbott announced seismic upgrades for 152 of British Columbia’s schools.
The upgrades follow a comprehensive reassessment of seismic safety at schools throughout the province involving the Ministry of Education, the Association of Professional Engineers and Geoscientists of British Columbia and UBC’s Department of Engineering.
Based on a re-evaluation of more than 500 schools previously identified for potential funding under the School Seismic Mitigation Program, the new assessment identified 152 schools with at least one ‘high risk’ building that needs to be addressed.
Outside of these ‘high priority’ schools, the department says options to fund upgrades to the remaining schools, which have buildings classified as ‘low’ or ‘medium’ risk, will be considered in 2013/14.
Along with the updated schools assessment, the three bodies have also been working together since 2005 to upgrade technical guidelines for seismic retrofits based on the latest scientific research and a study of major earthquakes around the world.