22.11.2009

Crane collapse in Milan

A large mobile crane collapsed in central Milan on Saturday thankfully there were no injuries.
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The failure caused the main boom to twist and buckle

The crane, believed to be a 500 tonne Krupp KMK 8500, (The design was a modified Gottwald AMK - the company was acquired by Krupp in 1988 this unit is possibly a 1989 model), was set up with a partially extended main boom and what looks like a full luffing jib, (The unit had up to 77 metres of luffing jib)to place an air conditioning unit onto the roof of a hotel in Via Franchetti, close to Milan’s Central Station.

The apartments on the 10th floor were damaged and although occupied at the time by a family with children they were frightened but unhurt.
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The luffing jib came down accross the top of the appartment blocks

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The crane damaged the top floor

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The jib mast was left dangling

Tenants have been evacuated from the building until the crane is removed and the buildings declared safe.
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Local reports suggest that a cable snapped, causing the jib to both collapse and twist, buckling the main boom.

However looking at the photographs it would seem that a supporting lug for the jib mast may have failed causing extreme side loads on the boom. What we do not know of course which happened first.

Update:

Calls coming into our office today suggest that this particular model.. although we still do not have the exact designation - was subject to susbtantial sideways deflection when fitted with a long luffing jib.

Given the age of the unit ..... around 20 years old... if this was the case then 20 years of such deflection will inevitably lead to risks of fatigue. Depending on how often it was used and if the deflection was significant.