Rectangular Box

@DIMENSION_08 {ttf}
@DIMENSION_09 {tbf}
@MATERIAL_01 {Mat1}
@COMMENTS {CommentText}


  • ShapeBuilder can generate beam cross-sections in the shape of a rectangular box. To define a rectangular box, use the following parameters.
  • The base section is a closed section consisting of top and bottom flanges connected by left and right webs to form a closed rectangular box, as illustrated in fig. 1. No options are available for this shape.
  • Optional dimensions @DIMENSION_10 and @DIMENSION_11 define two shaping parameters, denoted α and β, respectively, which are used to round the corners of the section. (Default value: α = β = 0.5).
  • Sectional shapes are defined in their own local coordinate system, which is assumed to coincide with the global coordinate system. If a fixed frame, FrameName, is specified, the local coordinate system coincides with this fixed frame.
  • The mesh density parameter, md, determines the level of mesh refinement. (Default: md = 4)
  • It is possible to attach comments to the definition of the object; these comments have no effect on its definition.

The rectangular box: base configuration

Figure 1. Configuration of the rectangular box
  • Fig.1 illustrates the base configuration of the rectangular box, which is composed of the top and bottom flanges, and the left and right webs.
  • The geometric configuration of the rectangular box if defined by the dimensions listed in table 1, which are also indicated in figs. 1, 2, and 3. Dimensions labeled in red are required. Dimensions labeled in blue are optional and are assigned the default value indicated in table 1.
Component Dimension Symbol Default Nb.
Rectangular box width w required 01
LeftWeb height hL required 02
LeftWeb thickness tL required 03
LeftWeb skew angle αL 90° 04
RightWeb height hR hL 05
RightWeb thickness tR tL 06
RightWeb skew angle αR 90° 07
FlangeTop thickness ttf tL 08
FlangeBot thickness tbf tL 09
Table 1. Dimensions defining the geometry of the rectangular box
  • Zone 1 of the rectangular box is defined as follows.
    • It comprises the following faces: TopFlangeLeft, TopFlange, TopFlangeRight, RightWebTop, RightWeb, RightWebBot, BotFlangeRight, BotFlange, BotFlangeLeft, LeftWebBot, LeftWeb, and LeftWebTop.
    • It is associated with material Mat1 , which can refer to material properties or solid properties.
Figure 2. Configuration of the left portion rectangular box        Figure 3. Configuration of the right portion rectangular box

The rectangular box: external edges

For the rectangular box, the following external edges are defined.

  1. TopFlangeOuter. This external edge comprises the outer side of the top flange along the line joining vertices MO–NO–PO–AO, see fig. 1.
  2. BotFlangeOuter. This external edge comprises the outer side of the bottom flange along the line joining vertices GO–FO–EO–DO, see fig. 1.