Strength of concrete

by James
(South Africa)

Hi,

I purchased a house where the previous lunatic cast a balcony floor using concrete lintels and hollow concrete pipe as a support. My plan is to prop the floor and replace the lintels with steel beams.I need to know what the minimum spacing between lateral supports should be to prevent the slab from collapsing.

My question is, theoretically if the ground was washed away from under a concrete slab and the slab was 120mm thick without reinforcing,how much would need to wash away before the slab collapsed?

A. Without a set of plans to look at, it is impossible for me to give you any suggestions. Concrete has very little tensile strength, especially without reinforcing. I would contact an engineer to inspect your concrete floor and give you the proper spacing for your steel beams.