civil engineering

Load is what a bar carries.

Ultimate load is what it can carry just before it breaks.

It might be better to say the ultimate load is maximum load a material can carry before failure, as some materials will not break (non-brittle) when the ultimate load is achieved but go ductile. It is based on the stress-strain character of the material.

The load is the force (or moment) applied to a structural unit.

Hello RCE,

The OP is specifically addressing steel bars, so I am assuming that the load is a tensile force. Steel remains ductile until yielding occurs after which, it behaves plastically until it finally fails at ultimate load which is substantially higher than yield load.

From the standpoint of structural design, yield stress is of more interest because it is considered to be the limit of useful stress...anything beyond yield requires very large deformations (strains) which are not acceptable in most structures. But, by definition, the yield point is not the same as the ultimate load.

And of course, the original poster has not designated steel bars composition, metallurgical structure, nor if thet have been cold worked, all of whic h factors determine mechanical properties requested.

milo