CIVILKITSengineering tools All tools
CivilKits/Calculators/Structural/Loading analysis/Structural / beams

structural / beams

Fixed-fixed beam with full-span UDL.

Calculate the restraint reactions, fixed-end hogging moments, midspan sagging moment, and elastic deflection for a beam fixed against rotation at both ends.

read the result

Make rotational restraint visible in the result.

A full-span UDL on a fixed-fixed beam creates hogging moments at the restraints as well as sagging moment in the span. The calculator shows both, so a midspan-only check does not hide the support action.

Governing equations

For uniform load w, RA = RB = wL/2. The internal end moments are MA = MB = -wL2/12, while the positive midspan moment is wL2/24. The elastic maximum deflection is wL4/(384EI) at midspan.

Sign convention

Negative end moments denote hogging under the convention used here. A support-reaction couple may be drawn with the opposite external sign; the reported internal beam moment is the quantity to compare along the member.

Keep it as an elastic load-case screen.

  • Both ends must genuinely restrain rotation and vertical translation.
  • Do not substitute the simply supported coefficients wL2/8 or 5wL4/(384EI).
  • Support settlement, joint flexibility, cracking, shear deformation, stability, stress, and code limits are not checked.
  • This is elastic analysis, not fixed-end member design.