Representing Curved Beams and Walls

Curved structural items are represented by Generic Section (GENSEC) elements, the geometry of which is defined by sweeping a 2D Catalog profile along a path. This path is represented by a Spine element, owned by the GENSEC, whose route is specified in terms of a sequence of member Spine Points (POINSP) and, optionally, Curves. For example:

There are six types of Curve, defined by setting the Curve Type (CURTYP) attribute, which govern the way in which the shape of the curve is specified.

The options are:

LINE

A straight line (this is the default)

RADI

A circular arc, defined by a radius and a conditioning point.

THRU

An arc passing through a specified through-point position.

BULG

An arc defined by a bulge factor and a conditioning point.

FILL

A fillet arc and two adjacent straights, defined by a radius and a pole position.

CENT

A fillet arc and two adjacent straights, defined by a circle center point, a radius and a conditioning point.

A Spine with only two POINSP members behaves in a similar way to a linear Section (SCTN). The first POINSP owned by the Spine defines its start position (equivalent to the POSS of the Section); the last POINSP defines its end position (equivalent to the POSE of the Section).

Items connected to a GENSEC are positioned and orientated relative to a set of p-lines which follow the same path as that defined by the GENSEC’s Spine; that is, the p-lines may be curved. These p-lines are referenced by attached items via Justification Line Datum (JLDATUM) and P-line Datum (PLDATUM) elements, which define the frames of reference to be used for positioning and orientating the attached items relative to the parent GENSEC.

Fittings and joints are represented by generic Fixing (FIXING) elements, the geometry of which is defined by reference to Catalog items. Fixings can own other Fixings, so that although they behave somewhat like the more restrictive Fitting and Joint elements, they are more versatile for representing compound fittings and joints.