Designed by University of Canterbury mechanical engineer Associate Professor Geoffrey Rodgers, innovative seismic dampers that challenge conventional construction wisdom are being used in Christchurch’s new state-of-the-art central city library, Turanga, to make it more quake-resilient – Photo courtesy of the University of Canterbury
UC engineering innovation boosts new city library’s quake resilience
Christchurch’s new state-of-the-art central city library, Turanga, incorporates innovative University of Canterbury (UC) engineering solutions that are designed to help it endure a large earthquake with minimal damage.
In March 2016, the Southbase-led design-and-build team behind the city’s flagship five-storey library, named Turanga, began mapping out how they would achieve a high level of earthquake resiliency. They turned to the acknowledged expert, UC mechanical engineer Associate Professor Geoffrey Rodgers.
Assoc Prof Rodgers leads the field in alternative systems that use dampers to both absorb energy in a big earthquake and prevent building damage. Getting the right structural engineering solution for Turanga – the largest public library in the South Island – is crucial to ensuring its future seismic resilience.
The conventional approach would have been to incorporate sacrificial design features to absorb energy and prevent building collapse. However, Assoc Prof Rodgers says: “It’s a solution that saves lives, but still results in high repair costs.”
As a safer, more cost-effective alternative, he had previously developed a low-damage structural engineering design solution for Forté Health’s new building in central Christchurch, where 96 extrusion dampers were installed throughout the building’s structure. His outstanding work in this area was recognised last year with the Royal Society Te Aparangi’s Cooper Award.
Similarly, Turanga includes extrusion dampers, larger than those used in the Forté Health building. They have been strategically bolted between key base walls and the foundation to act as motion restraints in the event of a large earthquake.
In all, 20 dampers have been used, following full prototype testing. Each seismic damper is a metre long and weighs 185 kg.
“Under a low level of shaking, this building will respond just like a fixed-base structure. Once you get beyond that low level of shaking, it has been designed to roll and move at the base, but in a controlled way,” Assoc Prof Rodgers says.