H-01 — from sketch to model

lines, nodes, and the assumptions that connect them.

sketch-to-model translator

build a frame. see the analytical model update in real time.

Choose a frame type, adjust geometry and supports, and watch the sketch transform into the nodes-and-elements model that analysis software actually uses.

frame geometry
type
bays1
width20 ft
height12 ft
supports
left
right
—
degrees of freedom
— nodes  ·  — elements  ·  — restraints
architectural sketch
analytical model
live equation
set values above to see the live calculation
EI = Product of modulus and inertia
EA = Resistance to axial deformation
K = Relates forces to displacements in the model
explained
The analytical model replaces real geometry with idealized nodes and elements. Beams become line elements with stiffness EI. Supports become boundary conditions (fixed, pinned, roller). The model only knows what you tell it — missing a support or misassigning a connection changes every result.
key concepts
overviewIdealizing real structures into analytical models

Every analysis model is a simplification. Real columns become line elements between nodes. Real foundations become support conditions (pin, fixed, roller). Real connections become moment releases or rigid joints. The art is choosing idealizations that capture real behavior without unnecessary complexity. A pin where there should be a fixed support changes everything.

every model is a simplificationReducing complexity while capturing real behavior

A real building has millions of molecules, complex connections, and materials that vary inch to inch. An analytical model reduces all of this to a handful of elements connected at discrete points. The art of structural modeling is choosing simplifications that capture the real behavior without unnecessary complexity. A bad model with perfect analysis gives wrong answers.

the three building blocksNodes, elements, and supports in a 2D frame

Every 2D frame model is built from three things: Nodes (points where members meet or supports exist — each has x, y, and rotation degrees of freedom), Elements (straight lines connecting two nodes — beams, columns, braces, each with E, I, A properties), and Supports (boundary conditions at nodes — pins, rollers, or fixed — that restrain specific degrees of freedom). The tool above lets you build a simple frame from these parts.

support types matterPin, roller, and fixed — how restraints change behavior

A pin support allows rotation but prevents translation (2 restraints: dx, dy). A roller allows both rotation and horizontal slide (1 restraint: dy only). A fixed support prevents everything (3 restraints: dx, dy, rotation). Choosing the wrong support type fundamentally changes the model’s behavior — a fixed base column develops moment at the foundation; a pinned base does not.

degrees of freedomCounting DOF to check model stability

Degrees of freedom (DOF) = the number of independent ways the structure can move. In 2D, each node has 3 DOF (horizontal, vertical, rotation). Each restraint removes one DOF. The formula: DOF = 3 × nodes − restraints. If DOF > 0, the structure can deform under load (this is normal). If DOF = 0, it’s a mechanism (can’t carry load). If DOF < 0, it’s over-restrained (redundant supports — statically indeterminate).