New standard brings Australia up to date


A new Australian standard released this week is the latest in storage systems and cold-formed steel structure knowledge and design

New standard brings Australia up to date
New standard brings Australia up to date

March 2, 2012

A new Australian standard released this week is the latest in storage systems and cold-formed steel structure knowledge and design.

Dematic Structural Design Manager Dr Murray Clarke, whose company manufactures the ColbyRACK range of storage equipment, says the AS4084-2012 standard for Steel Storage Racking will play a vital role in ensuring workplace safety on a day-to-day basis.

"The new standard is a rack-by-rack, application-dependant proposition, which signals the switch from using a 'permissible stress' design philosophy to a
'limit states' design approach," Dr Clarke explains.

"This move brings Australia into line with most of the advanced rack designs codes in the world, including the European racking standard EN15512: 2009 and the Rack Manufacturers Institute Specification from North America," he says.

Dr Clarke, who is a member of the Standards Australia committee for steel storage racking, says the new standard will now also be
in line with the relevant cross-referenced companion Australian standards, including AS/NZS4600: 2005 Cold Formed Steel Structures and AS4100-1998 Steel Structures.

"From a structural design perspective, the limit states approach offers advantages over the permissible stress format," Dr Clarke explains.

"It allows the designer to consider the application of different margins of safety to different types of loads such as dead loads, storage loads, live loads and seismic loads.

"This will facilitate design optimisation and guarantee a prescribed level of safety across different combinations of loads.

"Limit states design also provides the designer with greater insight as to how the structure will behave in the event of an overload that approaches the true collapse load of the system."

Other significant changes in the new standard include vastly expanded and improved testing provisions, including statistical evaluation, and the inclusion of advanced methods of structural analysis and finite element analysis.

"Compared to the old standard from 1993, the new standard has the potential to result in more structurally efficient and finely tuned designs," Dr Clarke says.

"The result is that the storage racks of today are generally lighter and cheaper than those of yesteryear, while still possessing the required minimum level of structural safety – and that’s good news for end users."

IF IN DOUBT GET IT CHECKED

As per the previous standard, storage system users should ensure their system is professionally audited every year. The reality is that many storage system users are either unaware or routinely ignore these requirements.

Recent rack collapses in NZ have shown the importance of regular system audits to identify existing rack damage that could compromise performance during a seismic event or overloading of the structure.

Failure to conduct annual audits could expose users to litigation and potential penalties should an incident occur.

WHAT AS4808-2012 DOESN'T COVER

Like the standard before it, the new steel storage racking standard is only relevant for closed-face racks such as Selective, Narrow-Aisle and Double Deep racking.

It does not cover open-face racks such as Drive-In or Cantilever racking.

When designing open-face racks, designers will need to seek guidance from other international standards and codes such as FEM 10.2.07 for drive-in racking and FEM 10.2.09 for cantilever racking.

These codes can be used in conjunction with AS/NZS4600-2005 Cold Formed Steel Structures to obtain structurally sound racking designs consistent with world’s best practice.

KEY CHANGES
AS4804-2012 Steel Storage Racking will contain a number of important changes storage system users should be aware of:


No changes to storage system configuration allowed without the approval of the equipment supplier or a structural engineer.

The vertical clearance requirement for pallets stored above heights of 6m has been increased from 75 mm to 100 mm. This is aimed at reducing the risk of accidental impact with beams during pallet put-away and retrieval.

The "flue space" between pallets backing on to each other has been increased by 50 mm, reducing the risk of an adjacent pallet being accidentally dislodged when storing or retrieving pallets. This increase in flue space also better accommodates the needs of insurance companies who often insist on a minimum flue space of 75 mm to allow adequate penetration of water from roof and rack-mounted sprinklers during a fire.

A minimum of two ground anchors must be used per baseplate on racks where forklifts are used.

Minor changes to rack load signage whereby the dimension from ground to first beam level, and from first to second beam level must be noted explicitly on signs.


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