Moment Distribution Method
Iterative hand method to analyse indeterminate continuous beams + frames
The moment distribution method (Hardy Cross method) is a classical iterative procedure for analysing statically indeterminate continuous beams and rigid frames without solving large simultaneous equations. Each joint is first assumed locked, fixed-end moments are computed for the loads, then joints are released one at a time and the unbalanced moment is distributed to the connected members in proportion to their distribution factors (relative stiffnesses), with carry-over moments passed to the far ends; the cycle repeats until the moments converge.
Although software has replaced it for production design, it remains the standard teaching tool for understanding indeterminate behaviour, is invaluable for quick hand checks of computer output, and underpins the moment-coefficient tables of IS 456 Cl. 22.5 (which are pre-computed continuous-beam results for standard load/span cases used for routine RCC beam/slab design).
- Continuous beam + portal-frame analysis
- Hand-check / sanity-check of software results
- Understanding the basis of IS 456 Cl. 22.5 moment coefficients
- Preliminary indeterminate-structure design
- Academic + competitive-exam structural analysis