Getting your bearings

Read the full story..

R&D engineer Chris Gannon of Robinson Seismic inspects a new isolation device, the RoGlider, which can be used for small, light buildings.

In March, soon after the February earthquake in Christchurch, Megan Devine – General Manager of Robinson Seismic Limited in Wellington – was waiting patiently for information about one particular building in Christchurch. “I know it moved,” she said, “but I’d really like anecdotal information, and to know how it fared compared to the hospital next to it.”

The building she was particularly interested in is the Christchurch Women’s Hospital – the only building in the city to have lead rubber bearings.

This seismic isolation system was invented and developed by the founder of Robinson Seismic, Dr Bill Robinson, and it has saved other buildings from earthquake damage in the past. For example, lead rubber bearings helped to protect the University of Southern California Hospital during the 1994 Los Angeles earthquake, and another building isolated with the lead rubber bearing system survived the 1995 earthquake in Kobe, Japan, with no damage or disruption to services.

“The lead rubber bearing is a device which in effect isolates a structure from ground movement or vibrations,” says Devine. “It consists of layers of rubber and steel, with a lead core (or plug) through the middle of it.”

The result is a much more controlled movement. “Instead of a building shaking wildly, it gently moves from side to side, returning with contents and people back to where it started. The device allows buildings to be operational straight after an earthquake.”

By May, reports indicated that the Christchurch Women’s Hospital barely lost bandages off the shelves, says Devine. While specific measurements are still to come, she says: “You can definitely see the difference between the Christchurch Women’s Hospital and the main hospital. There’s not a hint of damage on the Women’s, but plenty in the main one”.

The lead rubber bearings have also been examined and the building has returned to its original position. “Everything performed exactly as expected,” she said.

With that sort of performance, it’s not surprising that there has been a global uptake of lead rubber bearings, with devices fitted in the USA, Japan, South America, Turkey, Armenia, Iran, Taiwan, China, Korea and New Zealand. “Pretty much any country with high seismic activity has taken up the bearing,” says Devine. The isolation system can also be used to lengthen the life of bridges, protecting against vibrations from traffic, trucks and trains.

Dr Robinson invented and patented the lead rubber bearing in 1978 while working at the Physics and Engineering Laboratory of the Department of Scientific and Industrial Research, IRL’s predecessor. “Bill Robinson really wanted the device commercialised; he wanted it out there doing some good,” says Devine. So in 1995, Penguin Engineering Limited was spun-off from IRL, and in 1998 the company changed its name to Robinson Seismic.

Robinson Seismic is one of the many businesses located on IRL’s Gracefield Campus in Lower Hutt, and Devine says that cooperation with IRL has been “very good for us”.

“IRL has exactly what we need,” she says. “Our research and development is done here, and our R&D engineer, Chris Gannon, came from IRL with IRL’s blessing. We use IRL’s workshops and material testing facilities. It suits us really well.”

As well as manufacturing its lead rubber bearings through a factory in Malaysia, Robinson Seismic is continuing to research and develop new isolation devices, such as the RoGlider.

“Lead rubber bearings are only suitable for larger buildings with a lot of weight,” says Devine. The RoGlider on the other hand can be used for much smaller and lighter buildings. It’s cheaper, and the device has already been fitted in two buildings at Whanganui Hospital.