RAM Concept Help

Section 38 Design resistance moment of beams

Included code sections - 38.1.

Excluded code sections - none.

Items a, b, c, d and e of section 38.1 are followed. Item f is applied under "Ductility" design.

Strain compatibility design is used. The maximum compressive strain is 0.0035.

See the Materials section for the material stress strain curves (γ m = 1.5 for concrete; γ m = 1.15 for reinforcement).

Reinforcement areas are not deducted from the concrete area.

Post-tensioning Tendon forces are ignored.

For cross sections with multiple concrete mixes, the stress-strain curve of each concrete block is used appropriately.

Axial forces (loads) on the section are either considered or ignored based on the settings in the design section or design span under consideration. If axial forces are chosen to be included, the cross section is designed to provide the required moment simultaneously with the given axial force.

At "T", "L" and "Z" beams, the beam stem and flanges may have significant tension and compression forces (at different elevations) that are required for moment equilibrium. If a cross section crosses the entire beam, these forces will largely cancel (while increasing the bending moment). However, if a cross section extends only part way across a flanged beam, then the section may have significant axial forces that are required for moment equilibrium; designing for the axial loads (by selecting the appropriate design section or design span properties) is necessary to ensure a safe design.

RAM Concept ’s design may exceed the maximum amount of allowed reinforcement, and therefore may create an over-reinforced section. See Ductility in the previous section for applying ductility requirements.

For cross sections with very small moments, the amount of reinforcement calculated by RAM Concept may exceed the amount necessary. This is because RAM Concept will not allow cross sections to have strains greater than 20%, which would be necessary to create a smaller compression zone. The reinforcement RAM Concept selects is that necessary for axial force equilibrium in the cross section.