One for the structural engineering type minds out there..

[cjard]

I've a loading diagram for my build that shows me point loads and UDLs of both live and dead loads in the finished structure

The timber frame co advise me that the minimum bearing surface of a point load will be 90x90mm, which I make out to be 8100 sq.mm

If a given concrete block is 3N/sq.mm, for that bearing surface I reason that the maximum load that can be applied is 24300 Newtons, or 24.3 KN

If my engineering diagram says the dead+live loads for a particular point (a column that contributes to supporting 2 landings) are 20 KN (10 dead and 10 live), would it be wise to use a block with a greater compressive strength? Or, is an assumed live load of 1 ton sufficiently tolerant that it's unlikely to be breached at all, much less by the required additional 4.3KN (circa 430kg) to crush the supporting block?

 

[jeds]

It's unlikely the block would fail in compression, but it might fail in tension. i.e. it might crack. The tensile (cracking) strength of concrete blocks is typically 10 to 15% of compressive strength. That's the reason for a padstone. The load on a padstone is no different and ends up on the same block but the padstone is far more resistant to cracking.