BendCheckSTRUCTURAL LAB
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INTERACTIVE STRUCTURAL ANALYSIS

Beams & frames.

Calculating…
m · kN · kN·m
01

Structural model

Drag a load along the beam to see diagrams update instantly
↑ yx →
Drag nodes and loads to edit
03

Forces & stresses

LIVE
Hover or tap to inspect a section Local axis x: from member start to end

Your structure, in motion

Choose an example, then drag nodes and loads. Diagrams update as you move.

  1. Model. «Node» adds a node at the clicked position. Click a member to split it while preserving loads. «Member» connects two selected nodes. Crossing members do not connect automatically.
  2. Load. Select a member and add a point load, uniform load or moment. Set its position by dragging, a slider or a number. For distributed loads, specify both ends of the loaded region.
  3. Supports & releases. Click a node to set its support. Click a member to release rotation at its start or end. This creates an internal hinge; a pinned support alone does not interrupt a continuous member.
  4. Sign conventions. Positive vertical loads act downwards, horizontal loads act to the right, and applied moments act counterclockwise. N is positive in tension; Q = dM/dx, positive M is sagging for a horizontal member running left to right. Diagrams are plotted to the right of the local member axis.

Stresses, labels & files

The tab σ shows normal stresses N/A − M·y/I, in MPa: red is tension, blue is compression. Choose a profile and its dimensions in millimetres. Drag the white marker or the slider to move the section along the member. Click the cross section to inspect a point through its depth. «Pin σ» adds a value label to the map; labels are saved with the model. At a force or moment jump, choose the left or right limit. This beam model excludes local stress concentrations at joints.

«Key values» labels ends, load boundaries and extrema; «Key + intermediate» adds equally spaced sections. Both limits (− / +) are shown at jumps. Exact values are available in the table below the diagrams.

«Save as» saves a .bendcheck.json model file. Older .epura.json files can still be opened. «Open» restores geometry, supports, loads, releases, material and section properties. A draft is also saved in this browser when local storage is available. Save a file to transfer a model between devices.

Explore

«Motion & deflection»: the cyan line shows the amplified deformed shape; hover to inspect displacements in mm. «Play» moves the selected point load; Esc stops playback. Position search checks 121 positions while keeping other loads fixed.

«Compare»: capture A and edit B. The purple dashed line shows A at the same scale. Changed geometry can be compared numerically without an overlay. A is stored separately in this browser.

Double-click a member dimension to edit its length; the end node moves with attached elements. Right-click to open the context menu. Ctrl+D copies the selected element; members are copied with their nodes, supports and loads, offset by +1 m. Each member can have its own section profile.

«Learn»: make a prediction and run an experiment. Return to restore your previous model. For an unstable model, the coral dashed line shows one possible mechanism rather than a loaded deflection.

Analysis method

Direct stiffness method for planar Euler–Bernoulli members, including axial and bending stiffness EA, EI. Uniform loads act per metre of actual member length in a global direction. Self-weight is not added automatically. Nonlinearity, shear deformation, buckling and design-code checks are not included.

For learning and preliminary analysis. Engineering design decisions require independent verification.