Originally Posted by
martinw
Dear Andrew,
I hope I have not misunderstood.
I can't back this hunch up with calculations , (wish I could) , but IMVVHO, adding E/G to fill a hollow steel section will almost certainly increase its resistance to twisting.
Suppose you have a hollow steel box section. Suppose it is vertical, and you are looking down into the box. If you twist it, it will not deform into a perfect parallelogram, but some parts of the walls of the box will be closer together than before, and some will be further apart.
If you repeat the process with the box filled with a material which is strong in compression, surely it has to increase the section's ability to resist twist, even if the filler is weak in tension?
My 2 cents.
Best wishes
Martin