Beam Input Panel
Enter all loads in one unit family. Use positive values for downward loads.
Formula Used
Vertical equilibrium: RA + RB = total downward load.
Moment equilibrium about A: RB × distance AB = ΣW(x - A) + ΣM.
Section shear: V(x) = reactions left of x minus loads left of x.
Section moment: M(x) = reaction moments minus load moments left of x.
Uniform load resultant: W = wL at the loaded segment center.
Varying load resultant: W = (w1 + w2)L / 2.
How To Use This Calculator
Choose the unit system first. Enter the full beam length.
Select a simple span or enter support locations. Add point loads and locations.
Enter uniform or linearly varying loads when needed. Add self weight if known.
Use the section field for a local shear check. Add capacities for quick ratios.
Press the calculate button. Review reactions, diagrams, stress, and capacity notes.
Example Data
| Input | Example value | Purpose |
|---|---|---|
| Span | 8 m | Defines total beam length. |
| Point load | 20 kN at 4 m | Models a column or hanger load. |
| Uniform load | 8 kN/m over full span | Models floor or roof load. |
| Load factor | 1.25 | Builds a factored load case. |
| Section check | 4 m | Reviews shear and moment at midspan. |
Beam Shear And Moment Planning
Beam design starts with load paths. A roof, slab, wall, or machine load reaches a beam. The beam then carries that load to supports. Shear shows vertical force transfer. Moment shows bending demand along the span. Both values guide safe member selection.
Why These Values Matter
A contractor may see one beam only. Yet that beam may support joists, masonry, equipment, or temporary work. Wrong reactions can overload posts. Wrong moment values can undersize steel, timber, or concrete. A fast calculator helps catch early mistakes. It also makes estimating clearer.
Common Loading Conditions
Point loads represent columns, wheel loads, or hanger loads. Uniform loads represent floors, roofs, finishes, and live loads. Triangular loads can represent soil, water, wind, or tapered tributary widths. Applied moments represent bracket forces or frame actions. Combined cases are common during construction planning.
Reading The Output
Support reactions show how much load each bearing receives. Positive reaction values push upward. Negative values suggest uplift. Shear at a chosen section helps check web capacity. Maximum shear often occurs near supports. Bending moment controls flexural strength. Maximum moment may occur where shear changes sign.
Using Results Carefully
This tool uses static equilibrium. It assumes straight beam behavior. It also assumes loads act in one vertical plane. Real beams may need lateral bracing checks. Continuous beams need stiffness analysis. Connections also need separate checks. Use the results for planning and review. Final designs should follow local codes.
Practical Checks
Check span length before entering loads. Measure support centers instead of clear openings. Keep all loads in matching units. Place each load from the left beam end. Add self weight when member size is known. Use service loads for deflection review. Use factored loads for strength checks. Compare reactions with bearing capacity. Compare moments with member resistance. Compare shear with web or stirrup capacity. Save the output with project notes. Flag unusual uplift early before choosing anchors or bearing seats.
Better Construction Decisions
Good shear and moment data improve quantity takeoffs. They help compare member sizes before detailed design. They also show where heavy loads should move. Temporary shoring can be checked early. Bearing plates can be sized with more confidence. Clear numbers reduce site confusion. Review outputs with a qualified engineer before final construction.
FAQs
What does shear mean in a beam?
Shear is the vertical internal force at a section. It shows how load transfers toward supports. High shear commonly occurs near supports.
What does bending moment mean?
Bending moment is the internal turning effect in a beam. It controls flexural stress and member depth in many designs.
Can this calculator handle overhang beams?
Yes. Select the overhang option. Then enter support locations inside the total beam length.
Can I add multiple point loads?
Yes. The form includes three point load entries. Use unused fields as zero values.
How is a uniform load converted?
A uniform load becomes one resultant load. Its magnitude equals intensity times loaded length.
How is a triangular load handled?
The tool treats it as a linearly varying load. Its resultant uses the trapezoid area and centroid.
What does a negative reaction mean?
A negative reaction suggests uplift at that support. Anchors or hold-down details may be needed.
Can I use factored loads?
Yes. Enter a load factor above one. All entered loads are multiplied by that factor.
Does this replace engineering design?
No. It is a planning tool. Final beam design needs codes, bracing checks, and connection review.
Why do shear and moment diagrams matter?
They show critical beam regions. These regions guide size selection, reinforcement, bearing, and temporary support planning.
Should I verify the results?
Review outputs with a qualified engineer before final construction.