These photos came from a forum site about building skyscrapers. I found the photos interesting and the commentary instructive, but just loved the title. Nice Dress, Sorry about the Shoes.

Like so many crane failures, the terra firma was the culprit. In this case, it was an 8″ raised slab concrete floor that some knucklehead assumed would support the crane outrigger loads. Punching shear is the name of the type of slab failure when a load just pushes through.

I’ve included the commentary from the Australian forum below, as well as the photos.

Common Problem, Nice dress, sorry bout the shoes
Seen it so many times.
Engineers put large cranes on slabs and they think with a bit of back propping that’s OK. Tri shores or in some cases only simple across props can hold up the titanic they think.
They forget about point loading only taking into account distributed loads.
Then they think the crane crew has x-ray vision looking through concrete to see where their outriggers and pads are directly over the back propping.

Think again ginger beers.

This a copy of an email sent to me;
Brand new $4,000,000,
250t Mobile Crane
Friday 8:30h – 26.09.08 –
Castle Hill, Sydney Australia,
$8,500 / Day

The mistake was to place the crane on the 8 inch concrete slab
As soon as the jib was all the way out, the slab broke

crane balanced for about one hour before the rest of the slab gave way to the crane

Except for the slightly harmed driver no one was hurt, but no one has seen the site manager since…