Temporary Works Wind Loading and Return Periods

[Anthony McLellan]

Hi TWf,

I would be interested in seeing a discussion/webinar on 'Wind loading and return periods for short duration construction stages in temporary works'.

In particular, very short duration installations/stages of construction. Say anywhere between 3 days to 1 month.

Regards,

Anthony

[Barnabas Ilko]

@Anthony McLellan, thank you for the suggestion. We are in the process of gathering information on various types of TW and requirements relating to these structures/equipment by various codes. We have a working document and awaiting the issue of the new wind code as well as the new formwork standard. This event will likely be held in Q4 of 2021.

[Shane Groom]

Hello Anthony,

While we wait for the TWF new / revised documents Barnabas mentioned, the following may be helpful to you.  Have a look at C H Wang & L Pham (2011) Design Wind Speeds for Temporary Structures, Australian Journal of Structural Engineering, 12:2, 173-177.

I came across this paper as it is referenced in ABCB Temporary Structures Standard.  This is for marquee's, grandstands, music festivals and large stages, etc.  It is NOT for temporary works such as precast panel propping, steel bracing, formwork, shoring, working platforms, crane lifts, construction sequencing, etc, etc.

This paper is very valuable for large temporary structures with roofs and side sheeting.  In particular, as soon as wind gusts are predicted or measured on site as exceeding an agreed limit, the Event Team can drop the side wall sheeting and greatly reduce the wind load on the structure.  They can also evacuate structures if needed.

Under the VBA, this is a Performance Solution that still achieves the same Structural Reliability and Safety required by the NCC and Australian Standards.

While none of that helps you with temporary works, one can argue you can achieve the same Reliability and Safety.

We have to be very careful if we decide to deviate from the Standards and the Deemed to Comply methods.  However, you should have at least 24 to 48 hours warning of a 1 in 100 year wind event forecast.  So if the Builder can implement a Wind Monitoring plan and they can install extra braces or props at short notice, then perhaps you can design for less than a 1 in 100 year wind event?

 

The above info is general in nature and shall not be relied upon for design or certification of any structure or project.  Always consult or engage an engineer for formal review, advice, design or certification.