ENGINEERING – TRUCTURAL ENGINEERING — BEAM & FRAME CALCULATOR
Continuous Beam 3Span
A precise tool.
What is the Continuous Beam 3Span & How does it work?
Continuous beams are structural members that extend over more than two supports, providing continuity that reduces deflections and moments compared with simply supported spans. The moment distribution method, introduced by Hardy Cross, iteratively balances the fixed‑end moments at each joint by distributing the unbalanced moments according to the relative stiffness of the adjoining members. For a three‑span beam, the stiffness of each span is k = 4EI/L, and the distribution factors are used to compute the final end moments, which are then used to determine shear forces and reactions.
M_{fixed} = \frac{w L^2}{8}
M_fixed = Fixed‑end moment for a uniformly distributed load on a simply supported span
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Frequently Asked Questions
What is a continuous beam?
A continuous beam is a structural member that extends over more than two supports, providing continuity that reduces deflections and moments compared to simply supported spans.
Who introduced the moment distribution method?
The moment distribution method was introduced by Hardy Cross.
How is stiffness calculated for each span in a three-span beam?
Stiffness of each span is calculated as k = 4EI/L, where E is modulus of elasticity, I is moment of inertia, and L is the length of the span.
What are distribution factors used for in continuous beams?
Distribution factors are used to distribute unbalanced moments according to the relative stiffness of adjoining members during the moment distribution method.
How does a continuous beam compare to simply supported spans?
A continuous beam has continuity between supports, which reduces deflections and moments compared to simply supported spans.
What is the purpose of the moment distribution method?
The moment distribution method iteratively balances fixed-end moments at each joint by distributing unbalanced moments according to the relative stiffness of adjoining members.
Can this calculator handle beams with different span lengths?
This specific calculator is designed for three-span beams, but it assumes equal spans. For beams with different span lengths, a more flexible calculation method would be required.
Results are for informational purposes only and do not constitute professional advice.