Recently a large Crane fell in Tampa and caused a lot of damage. I heard people say it was “rated” for wind speeds that were less than the wind speeds of the recent hurricane. How can it be measured down to certain winds speed, as in, 100 MPH is safe, but 130 MPH is not safe?
In: Engineering
We do wind load calculations. You can think of the crane as a sail that catches the wind. We calculate the approximate area of the crane, estimate wind speeds at different elevations (e.x. the wind gets faster the farther up from the surface of the earth), and determine the forces created at different wind speeds. The size and shape of the load (what the crane is lifting) is also included. Safe wind speeds are based around what the crane can withstand (its structure) and that the bearing surface will support (like a pile foundation, a barge, tracks on dirt, etc).
You can read about the Big Blue engineering disaster at Miller Park for a good lesson on wind loads. A 400+ ton section of roof fell as it was lifted by a GIANT crane because bad management pushed for an unsafe lift and ironworkers paid in blood.
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