But strength alone is not enough. “Brute force does not work here,” says Jeff Smilow, executive vice president of building structures at WSP in New York. “We have fewer engineering opportunities so we have to be more innovative. We have to work with the wind instead of fighting it. The goal is to find out what works, what shape responds best to the wind and reduces the acceleration, not just to add structure unnecessarily.”
Like the Shock Absorber in a Car
One option is to adjust the shape of the building to make it more aerodynamic, introducing openings to allow the wind to pass through or adding curves at critical locations along the façade to minimize the ‘vortex shedding’ response which causes high acceleration. WSP works closely with architects to refine the shape of a building, using wind tunnel analysis.
The engineers can also reduce the acceleration of the movement by using a damper, similar to the shock absorbers in a car. This is a heavy weight placed high up in the building, either solid, in the case of a tuned mass damper, or liquid, as with a slosh damper. As the building moves, the weight moves too but more slowly – thus slowing the acceleration of the tower.