FM-2D

Unsaved project

Project name Frame type Units Preloaded example

Number of storeys Bay widths (mm, comma-separated)

Building plan and column tributaries

Building length — studied direction (mm) Building length — transverse direction (mm) Number of lateral frames — studied direction End-column tributary length — studied direction (mm) Interior-column tributary length — studied direction (mm) Column tributary length — transverse direction (mm)

Import Excel workbook [Optional]Download Excel template (.xlsx, mm)Workbook length units

Storey	Height (mm)	Column splice	Splice height / storey height

Splice height is measured from the floor below. When enabled, this storey's column section is below the splice; the next storey's section is above it (top storey uses its own section).

MF columns — section at every storey / axis

MF beams — section at every floor / bay

Gussets - corner and mid-beam properties at every storey / bay

Blank fields use the common gusset inputs under Supports & Connections. Enter three buckling lengths separated by commas; their average must be positive and defines the spring stiffness (individual lengths may be signed, as in the original workbook). Plate width defaults to zero. Braces meeting at the same beam plate must use the same width.

Extended endplates — connection at every floor / bay

tep x bep x db x pt x g x rows x stiffener, optionally x BP x tbp x DP x tdp. Dimensions are mm; rows = 4 or 5 (8 or 10 bolts); stiffener/BP = 0 or 1; DP = 0, 1 or 2 sides. One specification per bay applies at both ends, using each joint's column section. Example: 20x250x22x80x140x4x0.

Doubler plates — thickness (mm) at every floor / axis

Frame and section assignments

Scroll to zoom; drag to pan. Select a member to edit its assignment.

Show sections

Font size 13

MF column supports Column splice connection MF connection Beam unbraced-length fraction Column axial-load optionColumn P–M gravity-load multiplier

FRAME MODELER 2D · WEB EDITION

About FM-2D

FM-2D is an open-source platform for creating, analyzing and visualizing two-dimensional building frame models in OpenSees. This browser edition supports steel moment-resisting and concentrically braced frames under lateral static and earthquake loading.

From model definition to results

Define geometry, sections, connections, gravity loads and mass; run eigenvalue, pushover, equivalent lateral force, dynamic or incremental dynamic analyses; then inspect floor responses, member forces, yielding and brace response. Dynamic model-uncertainty campaigns provide response statistics and exceedance bounds.

Runs on your computer

The OpenSees WebAssembly engine and supporting data are embedded in the application. Calculations run in your browser without MATLAB, a local OpenSees installation or an analysis server. Projects and results remain in browser memory until saved or downloaded. External information links open only when selected.

Author and contact

Developed by Ahmed Elkady, University of Southampton, United Kingdom.
a.elkady@soton.ac.uk · Author homepage · FM-2D repository

Documentation

Read the browser user manual for the current workflow, a worked example, modeling assumptions and result interpretation. It follows the organization and terminology of the original FM-2D Manual, version 5.2606.3 (June 2026), with browser-specific differences identified.

How to cite

Elkady, A. (2022). “FM-2D - open-source platform for the 2-dimensional numerical modeling and seismic analysis of buildings.” SoftwareX, 17, 100927. doi:10.1016/j.softx.2021.100927

Scope and use

This web edition is under development and implements the features described in its browser manual. The original desktop manual also describes features that are not available here. Review modeling assumptions and analysis outcomes before interpreting results; numerical non-convergence does not by itself establish physical collapse.

Licence and acknowledgments

© 2020–2026 Ahmed Elkady. FM-2D is free software distributed under the GNU General Public License v3, without warranty. The OpenSees engine and numerical libraries retain their respective notices and licences.

Engine copyright and licences

The Regents grants permission, without fee and without a written license agreement, for (a) use,
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Permission to incorporate this software into products for commercial distribution may be obtained
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This software program and documentation are copyrighted by The Regents of the University of California.
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License
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Frame Modeller-2Dv1.2611

Member formulations

Building plan and column tributaries

Frame and section assignments

Bracing

Moment-frame to gravity-system links

RBS geometry

Load values

Gravity-load combination coefficients

Mass combination coefficients

Application and distribution

Columns and panel zones

Beams

Endplates and bolts

Braces and gussets

Composite action

Ground-motion library

Visualization Options