Connection design, anchor plate, AS 4100 max pitch requirements

[Curious student]

Hi,

AS4100 Clause 9.6.3 limits the max pitch spacing of bolts in a connection design to lesser of 15tp or 200mm. I have an anchor plate design with post installed anchors at a pitch (centre to centre spacing) of 430mm. Unfortunately the pitch can not be reduced any closer because this is to avoid critical elements in the existing concrete. What actually governs this maximum pitch requirement the standard is setting? The supplementary doesn't offer much information to help.
What should I do now since the pitch exceeds the standard?


Thanks in advance

 

[Agent666]

In NZS3404 (and in AS4100 I believe), it states something along the lines that this limitation is to do with bolts too widely spaced not clamping together plies sufficiently. Such that there is an increased chances of corrosion occurring as water and rubbish materials can be sucked into any gap that forms which can accelerate corrosion in this gap. I believe that is the primary consideration.

Now if you had a thick rigid baseplate like 50mm thick this would be less of a concern than a 10mm plate. Apply some judgement.

 

[Curious student]

Thank you for your response Agent666 - that makes sense.
The said anchor plate will be fully encased in concrete, reducing the chance of corrosion occurring.