Engineering · Statics & Structural Analysis

2D Frame Stiffness Analysis Calculator

Screen the lateral sway of a one-storey rigid portal frame and distribute storey shear between two entered column flexural stiffnesses.

Engineering · Statics & Structural Analysis

Enter the engineering model

Explicit properties, geometry, units and assumptions
  1. 1EnterProvide the known values
  2. 2CalculateResults update automatically
  3. 3VerifyReview the details and units
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Visual modelSchematic · not to scale
Statics & Structural Analysis: portalSway visual explanationA simplified diagram showing the relationship represented by the selected calculator mode. It is explanatory and not a fabrication, safety or scale drawing.rigid-beam portal swaycolumn shear follows each entered EI
The diagram explains the selected relationship only. Dimensions, symbols and proportions are illustrative; use the entered values and stated assumptions for the calculation.

Keep every unit basis, sign convention, property source and idealization consistent. Values stay in this browser.

Engineering calculation result

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Understand the structural model

How a portal shares lateral load

A rigid portal frame resists lateral load through column bending. The stiffer column attracts more storey shear, while the common beam displacement keeps both column tops compatible.

Relationship used

For a rigid beam and fixed column bases, kᵢ=12EIᵢ/h³; Δ=H/(k₁+k₂); Vᵢ=kᵢΔ and fixed-end column moment magnitude is 6EIᵢΔ/h².

Worked scenario: Two identical columns with E=200 GPa, I=8×10⁻⁵ m⁴ and height 3 m resist a 20 kN lateral load with 1.406 mm ideal sway.

Keep the boundary visible: This is a one-storey first-order sway model, not a general frame or building analysis.

Quick guide

How to use this calculator

  1. Choose the analysis mode that matches the physical model before entering values.
  2. Enter properties, geometry, loads, states and coefficients from one consistent unit and sign convention.
  3. Use the intermediate outputs to audit the relationship, then retain the stated idealization before applying it.

Calculation method

Transparent engineering model

For a rigid beam and fixed column bases, kᵢ=12EIᵢ/h³; Δ=H/(k₁+k₂); Vᵢ=kᵢΔ and fixed-end column moment magnitude is 6EIᵢΔ/h².

The calculator evaluates only the declared relationship and preserves visitor-entered assumptions rather than selecting materials, factors, components or standards.

Worked example

Worked example

Two identical columns with E=200 GPa, I=8×10⁻⁵ m⁴ and height 3 m resist a 20 kN lateral load with 1.406 mm ideal sway.

For a rigid beam and fixed column bases, kᵢ=12EIᵢ/h³; Δ=H/(k₁+k₂); Vᵢ=kᵢΔ and fixed-end column moment magnitude is 6EIᵢΔ/h².

Supported inputs

Precision and limits

Analysis, not approval

This is a transparent one-storey portal sway model, not a general building analysis. P-delta effects, joint size, panel zones, connection flexibility and code combinations are excluded.

Standards and properties

Material properties, allowable values, load combinations, safety factors, correlations, manufacturer data, codes and jurisdictional requirements are not supplied automatically.

Units and precision

Use one consistent unit basis. Results retain working precision but cannot be more accurate than the entered measurements and properties.

Privacy

Entered engineering values and results stay in this browser and are not sent to analytics or third parties.