Look at the footer along the bottom of the canvas. It shows the current length and force units. This walkthrough assumes meters and kN. You can change them there at any time; units affect display only, and switching them never changes the underlying model.

Press L (or B) for the beam tool. Make your first click on the origin (the fixed point the canvas starts with). The start of the beam snaps onto it, which adds a coincident constraint and locks that end in place.

Then move to the right and make your second click with the line close to level. Within about 2° of horizontal it snaps flat and adds a horizontal constraint automatically. Don’t worry about the length yet; you’ll set that next.

Press Esc to return to the pointer when you’re done.

Press D for the dimension tool and click the beam, then type 2 for the length. The beam snaps to exactly 2 m and stays there, and because the other three freedoms are already locked, it changes from blue to fully defined: white in dark mode, black in light mode.

This is the parametric part: the dimension is a driving constraint, not a label. Change the number later and the geometry moves to match.

Press S for the pinned support tool and click the left end of the beam. It will snap onto the existing endpoint. Pinned supports are a single click.

Now open the support tool's sub-tools and pick the rolling support, and click the right end. Rollers need a second click to set which direction they restrain: click directly below the node so the roller sits under the beam and restrains vertical movement. It will snap to vertical.

A roller pointing the wrong way restrains the wrong direction and leaves the beam free to move, and the structure becomes a mechanism and won't solve. If nothing happens after you add the load, this is the first thing to check.

Press F for the force tool and click near the middle of the beam. As you approach midspan it snaps there and adds a real midpoint constraint, so the load stays at the center even if you later change the span.

A control line appears for the load direction. Click below the beam to point the arrow straight down; it snaps to vertical. Then type 10 when prompted for the magnitude.

The model solves the instant it has enough information; there's no “run” button. You should now see reaction arrows at both supports, each reading 5 kN upward, and green stability bands along the beam showing the solver considers it stable.

If reactions aren't showing, check the Show/Hide menu; forces may simply be toggled off. The same menu switches reactions between separate Rx / Ry components and a single resultant arrow.

Everything should match the textbook values for a simply supported beam with a central point load:

This exact case is fixture D1 in our automated benchmark suite. See Validation.

This is where a live solver earns its keep. Try each of these and watch it re-solve:

• Drag an endpoint. The whole model re-solves as you move: reactions update continuously, not on release.
• Change the span. Double-click the 2 m dimension and type 4. The load stays at midspan because of the midpoint constraint, and the reactions stay at 5 kN, since span doesn't affect reactions for a central load.
• Move the load off-center. Delete the midpoint constraint in the Constraints panel, then drag the load. Now the reactions split unevenly: the nearer support takes more.
• Swap the roller for a pin. The structure becomes indeterminate, and the section starts to matter. Open the Materials panel and change the section to see the answer shift.
• Click a beam to see its internal forces in isolation.

Your work saves automatically. Use the share option to publish a read-only link that anyone can open and drag, no account needed on their end. Related models can live as tabs in one workbook; see the Interface Tour.