A concrete hypothesis
Precast
concrete wall panels have many advantages over traditional building
materials. They are made off site, can be erected quickly, provide
design flexibility and are cost-effective.
But their use on the Landmark building has posed an interesting engineering question. When precast concrete panels are suspended from a reinforced concrete beam, how accurately can the beam’s deflection be predicted over time?
It’s the question fourth year Civil and Water Engineering (Honours) students Bill Harding and Daniel Keller hope their Landmark project will answer with far-reaching consequences.
"In recent times there has been some concern about the reliability of the
formula given in Australian Standard AS 3600-2001 for the deflection of a
reinforced concrete beam," Keller said. "This formula is based on
compressive strength, which is not necessarily a good predictor of elastic
modulus (an object’s tendency to be deformed) and can under-predict actual
deflections by a factor of two to three."
With concrete test specialists Ancon, the pair is testing the concrete in
cylinders from nine beams in building 3A at different times over the period
of a year and, with a professional surveyor, will also analyse the effects
of actual deflections occurring by continually surveying the beams on site.
"The project entails a practical analysis and evaluation of the results to
come up with a hypothesis for an altered or new formula that will more
accurately predict the deflection of reinforced concrete beams," Harding
said.
Keller said the project has given the pair exposure to industry
professionals and "hands on" testing and sampling. And this story already
has a happy ending – Keller and Harding have been offered jobs with a
prominent North Adelaide-based civil engineering firm.