AS3600 - Non-standard Cogs and Hooks

[djs123]

Hi,

I am considering use of non-standard cog. For N12 L bar the required cog length is 155 mm. The commentary indicates this is mainly due to manufacturing limitations but it states "lengths shorter than these should be specified with caution as they would not provide the necessary anchorage assumed in Clause 13.1.2.6" but it provides no indication of what to do if you want to use shorter cogs. Ausreo indicates they can do 100 mm, so say I want to design using a 110 mm length cog what is the appropriate way to consider the development length?

Thanks

 

[rscassar]

I had something similar to this not so long ago when I wasn't specifying a cog length but justify what capacity I could use for a non-standard cog used in a 1970's building. I remember looking thru eng-tips for non-standard cogs and decided to use the development of the straight extension of bar. For your example, 110mm cog - 3*bar diameter = 74mm. Development length to AS3600 = 348mm (depending on the factors you use), so I would only use a maximum 20% development.