Christchurch’s newest overpass, which features world-first quake-resilient technology, is scheduled to open this week.
Developed in Christchurch by University of Canterbury (UC) engineers, it has been described as the ‘Ferrari’ of bridges at 100m in length and consisting of three spans over two piers.
The structure provides an important link between the growing south-western suburbs of Christchurch and the city centre, passing over SH73 Curletts Rd, which is also of strategic importance according to Christchurch City Council’s transport planning and delivery manager Lynette Ellis.
The seismically-resilient connections at the bridge piers of the new $30 million Wigram-Magdala Link overbridge project are engineered to minimise post-earthquake damage.
The seismically resilient bridge piers or columns are designed to sustain different levels of earthquakes without damaging the column, specifies University of Canterbury associate professor Alessandro Palermo.
“The engineering design incorporates novel dissipative fuses and post-tensioning cables acting as rubber bands to allow the bridge columns to bounce back to the original position and not lean in on one side. UC is the first institution and New Zealand is the first country in the world to have it implemented in a real structure.”
Palermo explains that in other countries, it might take decades to see the first implementations of this technology.
This technology, which has been embraced by the building industry for new commercial structures around Christchurch and elsewhere in New Zealand, presents a shift in design focus to consideration of the ability to repair a structure following an event and allow more rapid and low-cost reinstatement as well as significantly less disruption.
“The asset owner, Christchurch City Council, and the designer, Opus International Consultants, felt that that such a critical bridge for the city should incorporate innovative technology to minimise post-earthquake damage and therefore also potential traffic disruption. UC and local professionals are working together to improve current design philosophies and deliver the next generation of structures which can experience several earthquakes with limited or no damage,” says Palermo.
“The Wigram-Magdala Link overbridge incorporates low-damage detailing comprising rocking piers with replaceable energy dissipaters and internal post-tensioning to assist self-centering following a major earthquake.”
The collaboration came about from interaction through the Canterbury Bridge Group, an initiative by UC to provide stronger links with the industry.
