Subject
The outer fibres of a beam or plate will deform plastically if exposed to excessive bending moments with which the thickness of the plastically deformed section increases. Ultimately, the beam will generate a plastic hinge when the bending moment is such that the plastically deformed sections converge at the neutral axis.
Plastically deformed material in a beam need not be considered as an operational failure. A successful ultimate limitstate design scenario can show that a beam or plate has deformed plastically on the understanding that the surrounding structure remains intact.
This type of calculation is difficult to perform in Frame or FE type software and requires specialist knowledge of their use. You can take the bending moments from a frame analysis and use ElastiPlast to see in seconds if the element has deformed plastically.
Calculator
The plastic stress calculator includes four calculation options; Rectangular bar or plate, rectangular hollow sections, tubular sections and I or H beams
(see CalQlata’s Steel Beam Sizes)
ElastiPlast calculates the bending moment required to achieve yield stress in the outermost fibres of a section, the bending moment required to achieve a plastic hinge and the moment required to achieve yield stress at a radial distance from the section’s neutral axis. The plastic stress calculator also lets you know how much of this bending moment is generated by elastic resistance and how much is generated plastically.
For help using this calculator see Technical Help
Plastic Stress (in metals) Calculator  Options
The plastic stress calculator includes calculation options for the following beam sections:
Plain rectangular plate or bar
Hollow circular tube
Hollow rectangular tube (RHS)
IBeam or HBeam
All the above calculation options have the following common input and output data:
You enter 
and the plastic stress calculator will provide: 


Bending moment for ‘y’

Elastic moment

Plastic moment

Minimum plastic moment

Plastic hinge moment

With the following additional input data for each of the above calculation options:
Check minimum system requirements