Modeling and Geometry Generation

A joint is a point in global space defined by X, Y, and Z coordinates. Joints connect elements, receive restraints and nodal loads, and carry translational/rotational degrees of freedom according to the analytical formulation.

A member is a one-dimensional analytical element between a start joint and an end joint. It is commonly used for beams, columns, braces, truss members, and other slender components. The start-to-end direction defines the member-local x-axis and therefore affects local-load directions and reported local forces.

Plates/surface finite elements model components such as slabs, walls, tanks, and mats where two-dimensional stress/result distributions matter. Solid elements are reserved for problems where a three-dimensional continuum stress state is necessary. Use the simplest idealization that can represent the behavior needed for the engineering decision.

Coordinates should come from a controlled structural grid or geometry source. Avoid accumulating almost-coincident joints through repeated manual edits. Small coordinate differences can create separate joints and therefore separate load paths even when elements appear to meet on screen.

For sections with unequal principal inertias, such as many I-shaped sections and rectangular members, orientation directly changes flexural stiffness about the direction of applied loading. A correctly sized member can therefore behave incorrectly if its analytical section orientation is wrong.

• A rigid frame member transfers the force/moment components allowed by its element formulation.
• A released member end removes selected transfer components.
• A truss idealization is intended to carry axial action rather than frame bending.
• A tension-only member adds nonlinear load-path behavior because it becomes inactive when its force state would be compressive.

Use the idealization that represents the physical system, then verify the resulting deformed shape and force path.

Translational repeat, circular repeat, mirror/generator tools, structural wizards, and imported geometry can accelerate modeling—but they can also reproduce a mistake hundreds of times. Generate from a small validated seed model, then run connectivity/duplicate checks after each major generation operation.

Surface elements have local axes used for applying some loads and interpreting element forces/stresses. Node ordering/orientation must therefore remain consistent, especially where pressure direction or reinforcement-result direction matters.

Prefer well-shaped elements and compatible node connectivity. Avoid unnecessarily distorted or extremely elongated elements, abrupt mesh transitions without compatibility, and disconnected adjoining surfaces. Refine the mesh where response gradients are high, then compare key engineering results across successive refinements until they are sufficiently stable for the intended decision.

1. Confirm shared nodes/compatible connectivity at adjoining surfaces.
2. Inspect element orientation/local axes.
3. Inspect distorted/poorly shaped elements.
4. Run a coarse model and record key displacements/forces/stresses.
5. Refine the mesh in critical regions.
6. Compare engineering quantities—not just colorful contours.
7. Stop refining when results relevant to the decision have adequately converged.

DXF or BIM-derived geometry can save time, but imported lines/objects may contain duplicated entities, tiny gaps, wrong vertical axes, unnecessary fragmentation, or physical-object definitions that do not directly equal the required analytical model. Reconcile coordinates, connectivity, units, section mapping, releases/offsets and model origin before analysis.