Saturday, July 30, 2011

New Zealand's Bridges: ANZAC Bridge across the Avon River in Christchurch (2)

March 2011 (-43.501 Degrees, 172.701 Degrees) ANZAC Bridge
The ANZAC Bridge has a 3-span voided slab superstructure on 4 column bents. It was built in 2000 and has a precast superstructure, precast bent caps, and precast columns. That makes it a very innovative design. However, the seismic design isn't easy to understand. It appears that the bridge was meant to survive the earthquake through brute strength. There are no dampers or plastic hinges designed to limit the seismic force. Moreover, the columns are too big to be damaged and so most of the damage was due to shear at the bent caps or at the column to bent cap connections. Bridges are supposed to be weaker in flexure than in shear to avoid catastrophic collapse in case the earthquake force is larger than expected. 

Creative Commons License
New Zealand's Bridges: ANZAC Bridge across the Avon River in Christchurch (2) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

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