SALT LAKE CITY – A professor at the University of Utah has discovered three causes of concrete and steel column failure, and the first is likely the cause of the Surfside, Florida condo collapse.
“The first is corrosion,” said Professor Chris Pantelides of the U of U Civil and Environmental Engineering.
High rise building columns have rebar inside which gives vertical strength and flexibility. Outside: reinforcement turns, most often in steel. These spirals can be exposed, wet and rusty … and the damage will spread.
âAnd if you see a little corrosion, that doesn’t mean it’s where you see it. It’s actually a bit left and right, âPantalides said.
Pantalides research, published in the Journal of Composites for Construction, tested steel, composite and hybrid columns under corrosive conditions, finding steel spirals prone to corrosion, which compromises the cement and can lead to corrosion. internal reinforcing bars.
In areas prone to such conditions, his article, co-authored by Michael Gibbons and Lawrence Reaveley, showed that hybrid columns suffered less corrosion.
Speaking about the environment in Utah, Pantalides said some areas experience more corrosion damage than one would expect in a dry climate, due to surface treatments of roads in winter.
âWe use salt water, ice salt on the bridges, so you’ll be surprised that some Utah parking lots actually have corrosion issues in the basement,â he said.
The second way columns can fail: stability issues related to load transfer.
In Surfside, a researcher found evidence of soil settlement at the tower site, and a nearby construction project created jerks in the South Champlain Tower that disturbed residents.
âIf the load shifts a bit to the right or to the left of the center of the column, then the capacity of the column starts to decrease almost proportionally,â Pantalides said.
The third factor that can damage the column is lateral or seismic movement. Pantalides did not see this as a likely factor in the Florida disaster.
The professor also pointed out reports that post-tensioned steel cables were used in the floor of the tower. Such cables support the weight of the floors but are not glued to the concrete, that is, if they corrode, they lose all structural effectiveness.
Pantalides had two messages for residents and managers of high-rise buildings:
- Maintenance is crucial.
- Buildings have a lifespan and sometimes need to be replaced.