TR.20.2.1 Prismatic Tapered Tube Property Specification

The following commands are used to specify section properties for prismatic tapered tube cross-sections. For the property types shown below, additional information can be obtained from Table 2.1 of the ASCE 72 document, 2nd edition.

General Format

property-spec  = { ROUND | HEXDECAGONAL | DODECAGONAL | OCTAGONAL | HEXAGONAL | SQUARE } START D1 END D2 THICK t

Where:

Parameter	Description
START D1	Depth of section at start of member.
END D2	Depth of section at end of member.
THICK t	Thickness of section (constant throughout the member length).

Prismatic tapered tube shapes

Square	Hexagonal (6 sides)
Octagonal (8 sides)	Dodecagonal (12 sides)
Hexdecagonal (16 sides)	Round

Notes

Section properties are calculated using the rules applicable for thin-walled sections.
Shear deformation is not considered for tapered I-Beams and tapered poles. This means that the SET SHEAR command has no effect on the deformation computed for members with these cross sections.

Example

UNIT …
MEMBER PROPERTY
1 PRIS ROUND STA 10 END  8  THI 0.375
2 PRIS HDC STA 15 END 10 THI 0.375
3 PRIS DOD STA 12 END 12 THI 0.375

See C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\US\Square_tapered.std and C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\US\Round_tapered.std for additional examples of designing members with prismatic tapered tube sections.