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Contractors World International Vol 7 No 5


Earthquake-resistant cranes

with new ISO standard

by Maria Lazarte - ISO

Do cranes pose a risk during earthquakes?

A new ISO standard for cranes used in seismically active

regions will make sure they do not.

We are no strangers to cranes towering over our city

landscapes, but how can we ensure they will not collapse

when an earthquake strikes?

The new ISO 11031 can be used to calculate seismic

loads, and sets out design principles for cranes destined

to work in seismically active regions and for cranes re-

quired to be seismically resistant.

Klaus Pokorny, Secretary of the ISO subcommittee

working on design principles and requirements for

cranes, explains:

“To make sure that cranes are safe, we first need

to calculate the seismic loads that show how a

crane will respond in moderate to severe

earthquakes. Then you can use design limit

states provided in two forms: serviceability limit

and ultimate limit.”

“The serviceability limit state (SLS) ensures

that the crane can withstand the effects of

moderate earth-

quake ground mo-

tions throughout its

service lifetime and

continue to operate

as intended. The ul-

timate limit state

(ULS) requires that the crane structure should

not collapse during severe earthquake ground

motions, and that the suspended load or any

other part of the crane should not fall or harm

the public, operators and workers,” adds


“Any evaluation should take into account

the regional seismic conditions as well as the

ground surface conditions at the crane location.

It’s also important to consider how the crane will

be used and any risks that could result from seis-

mic damage,”

“Not only will ISO 11031 add a layer of con-

fidence to the industry, it also provides a com-

mon technical language so that manufacturers,

users and owners understand each other clearly,

no matter where they are – a boost for global


ISO 11031 was developed at the request of Japan

who, following the 1995 earthquake in Kobe, emphasized

the need for a standard to ensure seismic-resistant

cranes. The secretariat of the subcommittee that devel-

oped the standard is held by DIN, the ISO member for


International Organization for Standardization


By CC BY-SA 3.0

Klaus Pokorny,

Secretary of the ISO

subcommittee work-

ing on design princi-

ples and requirements

for cranes

Marunouchi area in Tokyo (2011) following a 8.9

richter scale earthquake. This was before the second

large quake