Double Box
 @DOUBLE_BOX_DEFINITION {
 @DOUBLE_BOX_NAME {DboxName} {
 @DIMENSIONS {
 @DIMENSION_01 {w}
 @DIMENSION_02 {d_{T}}
 @DIMENSION_03 {d_{B}}
 @DIMENSION_04 {h_{R}}
 @DIMENSION_05 {t_{R}}
 @DIMENSION_06 {α_{R}}
 @DIMENSION_07 {t_{L}}
 @DIMENSION_08 {t_{T}}
 @DIMENSION_09 {t_{B}}
 @DIMENSION_10 {h_{L}}
 @DIMENSION_11 {t_{L}}
 @DIMENSION_12 {α_{L}}
 @DIMENSION_13 {t_{R}}
 @DIMENSION_14 {t_{T}}
 @DIMENSION_15 {t_{B}}
 @DIMENSION_16 {α}
 @DIMENSION_17 {β}
 }
 @MATERIALS {
 @MATERIAL_01 {Mat_{1}}
 }
 @IS_DEFINED_IN_FRAME {FrameName}
 @MESH_DENSITY {m_{d}}
 @COMMENTS {CommentText}
 }
 }
Notes

ShapeBuilder can generate beam crosssections in the shape of a double box. The double box consists of a single zone. No options can be defined for this sectional shape.

Optional dimensions @DIMENSION_16 and @DIMENSION_17 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, m_{d}, determines the level of mesh refinement. (Default: m_{d} = 4)

It is possible to attach comments to the definition of the object; these comments have no effect on its definition.
The double box: base configuration
Component 
Dimension 
Symbol 
Default 
Nb. 
double box 
width 
w 
required 
01 
double box 
location 
d_{T} 
0.0 
02 
double box 
location 
d_{B} 
d_{T} 
03 
Right box 
height 
h_{R} 
required 
04 
Right box 
thickness 
t_{R} 
required 
05 
Right box 
angle 
α_{R} 
90° 
06 
Right box 
thickness 
t_{L} 
t_{R} 
07 
Right box 
thickness 
t_{T} 
t_{R} 
08 
Right box 
thickness 
t_{B} 
t_{R} 
09 
Left box 
height 
h_{L} 
h_{R} 
10 
Left box 
thickness 
t_{L} 
t_{R} 
11 
Left box 
angle 
α_{L} 
90° 
12 
Left box 
thickness 
t_{R} 
t_{R} 
13 
Left box 
thickness 
t_{T} 
t_{R} 
14 
Left box 
thickness 
t_{B} 
t_{R} 
15 
Table 1. Dimensions defining the geometry of the double box.

The base configuration of the double box is shown in fig. 1, 2, 3, and 4. No options are available for this shape.

The geometric configuration of the double box if defined by the dimensions listed in table 1, which are also indicated in fig. 1, 2, 3, and 4. Dimensions labeled in red are required. Dimensions labeled in blue are optional and are assigned the default value indicated in table 1.
The double box features a single zone.

Zone 1.

The left box comprises the following faces: Lbox_TopFlangeLeft, Lbox_TopFlange, Lbox_TopFlangeRight, Lbox_RightWebTop, Lbox_RightWeb, Lbox_RightWebBot, Lbox_BotFlangeRight, Lbox_BotFlange, Lbox_BotFlangeLeft, Lbox_LeftWebBot, Lbox_LeftWeb, and Lbox_LeftWebTop.

The right box comprises the following faces: Rbox_TopFlangeLeft, Rbox_TopFlange, Rbox_TopFlangeRight, Rbox_RightWebTop, Rbox_RightWeb, Rbox_RightWebBot, Rbox_BotFlangeRight, Rbox_BotFlange, Rbox_BotFlangeLeft, Rbox_LeftWebBot, Rbox_LeftWeb, and Rbox_LeftWebTop.

Is associated with homogeneous material properties, Mat_{1}.
Figure 1. Overall configuration of the double box
Figure 2. Detailed configuration of the left box Figure 3. Detailed configuration of the right box
Figure 4. Detailed configuration of the central web