Create Sections

Each structural column or beam displays in the 3D model as a section (GENSEC) element. Each straight or curved section comprises straight and curved segments and its geometry is defined by extruding a 2D catalogue profile along a path. The path lies on a plane and is represented by a SPINE element, owned by the GENSEC, whose route is specified by a sequence of Spine Points (POINSP).

POINSPs are created at the start, the end and at each change of direction. Each segment linking adjacent spine points can be a straight line or circular arc achieved by inserting Curve (CURVE) elements.

GENSECs can be connected to other GENSEC elements, fittings and joints can also be applied to them.

A GENSEC element can be owned by a FRMW or a SBFR element and each element which makes up a GENSEC element has attributes unique to each of them.

GENSEC

A GENSEC can represent any component whose geometry is defined by sweeping a 2D profile along a linear or curved path (its SPINE element). It has a uniform cross-section along its length, defined by reference to a Catalogue Profile element.

SPINE

A SPINE defines the path through which a cross-sectional Profile must be swept to generate a GENSEC. The route of the Spine is defined by a sequence of Spine Points (POINSP): one at the start, one at the end, and one at each change of direction. Each segment linking adjacent Spine Points can be either a straight line or an arc of a circle: the latter is achieved by the insertion of a CURVE element. In its simplest form, the SPINE is defined as a line between two fixed points. In its more general form, where the SPINE consists of a sequence of straight and/or curved segments, it can represent, for example, curved beams or curved walls.

POINSP

A POINSP element defines the start and end of a SPINE path, and any location along the path at which there is a change of direction.

CURVE

A CURVE element defines a segment of a SPINE path. It defines the geometry of the SPINE between the POINSPs either side of it in the members list.

The geometry of a section is defined by two types of properties setting:

• Its cross-section is defined by reference to a Specification Reference (SPREF) element (for example, I‑beam, T-section and Channel).

• All other aspects of its geometry are defined by setting specific design properties (in most cases these are set automatically by the application as the 3D model is manipulated graphically). Two of the most important properties are the Start Position and the End Position, since the positions of these points effectively determine the length and orientation of the item.

To provide a method for referring to individual edges and faces of a section, each is identified by a named line which runs along the length and curve of the section. These reference lines (which are derived from the section’s profile definition in the catalogue) are called Plines. As an example, some of the most commonly used p-lines for an I-shaped Profile might be positioned and named as:

Note:
Refer to Structural Catalog for further information.

Nodes

The application uses the concept of Nodes to represent basic analytical points within a structure. Nodes have two main functions:

• To identify the points at which logical connections are made between adjoining sections.

• To define how applied stresses can affect individual points in the structure (for passing design data to separate stress analysis programs).