This underground space displays some of the 135 base isolators that Te Papa sits on. These devices ‘put the brakes on’ and reduce the severity of the shaking felt inside the building in the event of a major earthquake, and protect the people and contents inside. The base isolators are large rubber blocks laminated with steel, and with pure lead columns inside. They are the invention of New Zealand scientist Dr William Robinson, and are now in use in buildings around the world in areas that are subject to earthquakes. The ingenious lead-and-rubber isolators both isolate the building from the earthquake and damp, or absorb, much of the shaking from the quake. In Quake Braker you can see a cross-section of a base isolator, a scratch pad that shows the movement between the building and its base, and a video that tells the ‘foundation' story of Te Papa. You can also try out an interactive ‘shake table’ illustrating how lead-and-rubber base isolators work in an earthquake. Base isolator bearings were pioneered in New Zealand by Dr Bill Robinson during the 1970s, and have enjoyed widespread adoption as a damage resistant seismic design solution for new and retro-fitted concrete buildings. Base isolation works by separating (“isolating”) the structure from the ground, and therefore the lateral forces of an earthquake. There are two types of base isolation – elastomeric and sliding – both of which are designed to take the weight of the building and let the foundations move sideways during an earthquake. Flexible elastomeric bearings consist of layers of bonded rubber and steel with a central lead core. The lead core softens when under pressure absorbing energy that would otherwise be transferred to the building. With a sliding system there is no energy absorption, just deflection through the bearing. With both types of base isolation, building movement during an earthquake is greatly reduced, meaning less risk of damage or injury. the best place to see a base isolator in situ in Wellington is Te Papa on the waterfront. Stairs just outside the entrance to the museum lead down to a “quake-breaker” viewing area. There are 152 base isolators beneath the museum, said to reduce the severity of any shaking by up to 80%. The display includes a base isolator in cross-section and an interactive demonstration of their function. The isolators used in Te Papa are of a different design from those used in Parliament Buildings, being square rather than rounded. Quake Breaker - Base Isolators - 4157.

• published: 16 Jan 2015
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