So, does a creature with the unnatural strength trait quadrupal that ability?

All comments would be appreciated

No, these abilities interact so that they add their multipliers, instead of multiplying each other.

So the result would be SB*3

That has been the overwhelming tendency of FFG policy regarding multiplying multiples, though much older examples exist in which a doubled double is a quadruple. There's a daemon in... Disciples of the Dark Gods, was it? Creatures Anathema? Either way, it had both the Daemonic and Unnatural Toughness trait. Its listed Toughness Bonus was quadruple its base.

That said, I'd say the best policy, if not clearly stated, would be the newest policy of "adding" multiples into a single multiplier, as stated by Darth Smeg.

I figured as much. I mean having a strength bonus of 40 is a little excessive for any creature, but I suppose that's what cyclone missiles and nukes are for eh?

Cheers