Free 2D Frame Analysis Software Online
A frame calculator that runs in your browser: define nodes, members, sections and supports, apply the loads and get the reactions and the axial, shear and bending moment diagrams of every member. Portal frames, gable frames and any 2D frame with inclined members, rigid joints or hinges.
- ✓Axial, shear and bending moment diagrams for every member
- ✓Inclined members with loads perpendicular to the member
- ✓Fixed, pinned and roller supports and internal hinges
- ✓Sections with area, inertia and modulus of elasticity
- ✓Metric, MKS and imperial units · save and share your models
Free with a Google account · daily free credits · Premium for unlimited use · no installation
Worked example: a gable frame
The example that opens in the calculator is a gable frame 8 m wide: columns 4 m high and a ridge at 6 m. It is pinned at A and on a roller at E. Loads: a horizontal force of 20 kN at B, a distributed load of 10 kN/m perpendicular to the left rafter BC and a vertical point load of 30 kN at 0.75 of the right rafter CD.
Nodes and supports
| Node | x [m] | y [m] | Support |
|---|---|---|---|
| A | 0 | 0 | Pinned |
| B | 0 | 4 | — |
| C | 4 | 6 | — |
| D | 8 | 4 | — |
| E | 8 | 0 | Roller |
Reactions
| Support | Reaction |
|---|---|
| A | Ax = 40.00 kN ← |
| A | Ay = 11.25 kN ↑ |
| E | Ey = 58.75 kN ↑ |
Check: the perpendicular load on the inclined rafter (10 kN/m × 4.47 m) has a horizontal component of 20 kN and a vertical one of 40 kN. Horizontal: 20 + 20 = 40 kN = Ax. Vertical: 40 + 30 = 70 kN = Ay + Ey. The bending moment at the knee B is 160 kN·m.
Video tutorial: analyze this frame step by step
Nodes, sections, members, supports, the three load types and the diagrams, in about three minutes.
How to analyze a frame
1. Nodes and sections
Enter the coordinates of each node and define the sections with their area, moment of inertia and modulus of elasticity. Different members can use different sections, for example columns and rafters.
2. Members and supports
Connect the nodes with members and place fixed, pinned or roller supports. Joints are rigid by default; add a hinge where a joint should not transmit moment.
3. Loads
Apply forces and moments at the nodes, point loads along a member and distributed loads on a member. On inclined members the distributed load acts perpendicular to the member.
4. Results
Check the free body diagram and calculate. You get the reactions and the axial, shear and bending moment diagrams. Save the model or share it with a link.
Frame analysis with the stiffness method
Portal and gable frames are usually statically indeterminate, so equilibrium alone does not give the member forces: the result depends on the stiffness of each member. The calculator assembles the stiffness matrix of the structure from each member's area, inertia and modulus of elasticity, solves the node displacements and then the internal forces, the same way structural analysis programs do. That is why it handles inclined members, rigid joints and indeterminate frames.
Frequently Asked Questions
Do I need to install anything?
No. The frame calculator is structural analysis software that runs in the browser, on a computer or a phone. Your models are saved to your account, so you can open them from any device.
What kind of frames can it analyze?
2D (plane) frames of any geometry: portal frames, gable frames, multi-bay and multi-storey frames, with vertical, horizontal and inclined members, rigid joints and internal hinges. Determinate and indeterminate frames are both solved with the stiffness method.
Which loads can I apply?
Forces and moments at the nodes, point loads along a member and distributed loads on a member. Distributed loads act perpendicular to the member, also on inclined rafters, which is how wind and roof loads are usually defined.
What results does it give?
The support reactions and the axial force, shear force and bending moment diagrams of every member, with the values at the key points.
Is the frame analysis software free?
Yes. Sign in with your Google account and calculate for free with daily credits. Premium removes the limit if you need unlimited calculations.