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Free diaphragm analysis calculator

Calculate max shear in flexible diaphragms and loads to shear walls under wind or seismic loading.
Free · No sign-up requiredInstant resultsFEA-powered
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How to use the free diaphragm analysis calculator

  1. 1

    Define diaphragm geometry

    Enter the diaphragm dimensions and the X-positions of each braced wall line from the left edge.

  2. 2

    Apply lateral loads

    Enter wind or seismic load as a uniform pressure (kN/m) or total force applied to the diaphragm.

  3. 3

    Review results

    Read the maximum diaphragm shear and the reaction force delivered to each braced wall line.

About this calculator

Perform fast analysis of simple flexible diaphragms using the Calcs.com Diaphragm Analysis Calculator. With support for unlimited loads and supports, plus highly accurate FEA based results for load distribution and in-plane shear, the Calcs.com Diaphragm Analysis Calculator is the fastest way to model and design diaphragms.

How to use the free diaphragm analysis calculator

The Diaphragm Analysis allows users to quickly analyze diaphragms in a few simple steps. Currently only flexible diaphragms are supported; forces are distributed to vertical resisting elements by tributary area and simple beam analysis (e.g. wood-sheathed diaphragms).

Signing up unlocks advanced diaphragm design and linking to wind and seismic analysis. The sheet has Key Properties (geometry, braced wall line positions), Loads (wind/seismic), and Summary (outputs and diagrams).

Key diaphragm inputsDiaphragm summary

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Frequently asked questions

What is a diaphragm in structural engineering?
A diaphragm is a horizontal structural element (floor or roof) that transfers lateral loads (wind or seismic) to the vertical resisting system (shear walls or braced frames). It acts like a horizontal beam spanning between braced wall lines.
What types of diaphragms does this calculator support?
The calculator currently supports flexible diaphragms, where forces are distributed to braced wall lines by tributary area. Rigid diaphragm analysis (distribution by relative stiffness) is available in the full Calcs.com platform.
How do I enter wind loads?
Enter the total lateral force or a uniform wind pressure along the diaphragm span. For AS 1170.2 wind loads, compute the design wind pressure and enter the resulting tributary load per unit length.
What is the difference between shear walls and portal frames in this context?
Both are vertical resisting elements. The calculator treats them identically - they are simply lateral force resisting elements at specified positions. The distinction matters for capacity design but not for the force distribution this calculator performs.
What does a full Calcs.com trial add over the free tool?
The free tool performs the diaphragm analysis. A full Calcs.com trial lets you link the diaphragm output directly to shear wall design calculators, save calculations to a project, and export a signed PDF report.

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