New bridge construction techniques tested by University of Canterbury (UC) experts could improve the performance of bridges during earthquakes while speeding up the construction and repair processes.
UC civil engineering students are testing new ways of building bridge piers using prefabricated concrete components rather than bridge components that are poured on site.
The construction method is known as Accelerated Bridge Construction and greatly speeds up the bridge construction process while offering other advantages such as better construction quality and safety.
Research supervisor Dr Alessandro Palermo says it is particularly important and useful when it comes to repairing and rebuilding bridge structures following a significant earthquake.
``A number of bridge structures throughout Christchurch, such as the Ferrymead and Colombo Street bridges, have been affected by traffic restrictions for over a year due to structural damage. With these new bridge construction technologies, these bridges could have been rebuilt in a matter of weeks rather than months.
``Our recent testing has focused on innovative new connections between footing and column components. These connections limit and constrain damage to small regions of the bridge structure that acts as fuses while protecting the rest of the structure from damage.
``Following an earthquake, these fuse regions of the structure can be easily repaired meaning the bridge can be back in service a short time after the earthquake event.
``Post tensioned steel bars or tendons act as a kind of elastic band which spring the structure back to its original position, meaning the structure is not left on a lean following an earthquake. This is particularly important as it means the bridge is likely to be safe for use immediately after an earthquake event by rescue vehicles.’’
One type of connection that is being tested uses mechanical couplers in the fuse region of the structure.
Masters student Sam White says use of couplers allows for replacement of only the damaged components of the bridge with no need for deconstruction or repair of the non-damaged components outside of the fuse region. This speeds up repairs and can also offer significant savings.
A video of the testing and repair process for the coupled bar connection can be seen at: http://youtu.be/lcH1SGyCetQ.
Testing of the new connection types continues this week at UC’s Structures Extension Laboratory.
ENDS