Steel Beam Deflection Calculator

Analyze span, stiffness, inertia, and loading together. Review deflection limits, reactions, moments, and slopes instantly. Download clean outputs for checks, documentation, and team sharing.

Beam Input Form

Example Data Table

Case Span (m) E (GPa) I (cm4) Load Max Deflection (mm)
Simply Supported + Midspan Point 6.00 200.00 8,500.00 20.00 5.294
Simply Supported + Full Uniform 6.00 200.00 8,500.00 12.00 11.912
Cantilever + Free-End Point 3.50 200.00 5,200.00 8.00 10.994
Cantilever + Full Uniform 3.50 200.00 5,200.00 4.00 7.215

Formula Used

Beam deflection depends on load pattern, span, elastic modulus, and second moment of area. The core stiffness term is EI, where E is material elasticity and I is section inertia.

Simply supported with midspan point load: δmax = P L³ / (48 E I)

Simply supported with full uniform load: δmax = 5 w L⁴ / (384 E I)

Cantilever with free-end point load: δmax = P L³ / (3 E I)

Cantilever with full uniform load: δmax = w L⁴ / (8 E I)

Deflection limit check: δallow = L / selected ratio

This calculator also reports slope, bending moment, and support actions using standard linear elastic beam relations for small deflection behavior.

How to Use This Calculator

  1. Enter a section name for reference.
  2. Select the support condition for the beam.
  3. Choose the matching load model.
  4. Input span in meters, modulus in GPa, and inertia in cm4.
  5. Enter point load in kN or uniform load in kN/m.
  6. Set the desired serviceability limit ratio, such as 360.
  7. Press calculate to view deflection, moment, slope, reactions, and the deflected shape graph.
  8. Use the export buttons to save the result summary and example table.

About This Steel Beam Deflection Tool

This calculator gives a fast elastic estimate for steel beam serviceability. It helps compare common boundary conditions and load cases without manual substitution into beam tables. The output is useful for early sizing, study work, checking homework steps, and reviewing whether a trial member passes a chosen deflection limit.

Because the page also reports slope, reactions, fixed-end actions, and bending moment, it supports more than a basic one-line answer. The plotted curve makes the deformation pattern easier to understand, especially when comparing a simply supported member against a cantilever with the same stiffness and span.

For design decisions, always compare results with the governing code, actual load combinations, local stability checks, connection behavior, and any section property reductions required by your project method.

FAQs

1. What does this calculator estimate?

It estimates maximum elastic deflection, slope, bending moment, and support actions for selected steel beam cases. It also checks the result against a user-chosen deflection limit.

2. Which input units should I use?

Use meters for span, gigapascals for elastic modulus, centimeters to the fourth power for inertia, kilonewtons for point load, and kilonewtons per meter for distributed load.

3. Why is elastic modulus important?

Elastic modulus measures material stiffness. A higher modulus means the beam resists bending more strongly, so predicted elastic deflection becomes smaller for the same geometry and load.

4. Why is moment of inertia important?

Moment of inertia describes how section area is distributed about the bending axis. Larger inertia increases flexural stiffness and reduces deflection under the same loading.

5. What is the deflection limit ratio?

It is a serviceability rule written like L/360 or L/240. The span is divided by that ratio to produce an allowable movement for comparison.

6. Is this valid for yielding or large deflection?

No. This page uses standard linear elastic beam equations. It does not model yielding, second-order effects, cracking, residual stress, or geometric nonlinearity.

7. Can I use it for different steel grades?

Yes, if you enter the correct elastic modulus and section inertia. Still, strength checks depend on grade, compactness, and design code, which are outside this tool.

8. How can I reduce beam deflection?

You can shorten the span, reduce load, increase section inertia, add support points, change the beam layout, or select a stiffer overall system.

Related Calculators

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.