STAAD.Pro Help

TR.3 Unit Specification

This command allows you to specify or change length and force units for input and output.

Description

The magnitude of numerical data that is entered in a STAAD model is determined by the unit of that data. STAAD.Pro supports numerical data based on both English and Metric unit systems.

The method used by STAAD.Pro to determine the unit of any value is by the previous UNIT command.

The UNIT command can set or change the unit of LENGTH, FORCE, or both. This can be set any number of times in a STAAD input file subject to the conditions noted below.

General Format

UNIT *{ length-unit  | force-unit }

where:

length-unit  = { INCHES | FT or FEET | METER | CM | DME | MMS | KM }
force-unit  = { KIP | POUND | KNS | | DNS | NEWTON | MNS | MTON | KG }

The following tables illustrate the unit and the relative factor against the primary base unit:

Table 1. Units of length in STAAD.Pro
Required Length Unit Base Unit Factor UNIT command parameter
English Inch Inch 1 IN
Foot Inch 12 FT (or FE)
Metric Meter Meter 1 ME
Decimeter Meter 0.1 DM
Centimeter Meter 0.01 CM
Millimeter Meter 0.001 MM
Kilometer Meter 1,000 KM
Table 2. Units of force in STAAD.Pro
Required Force Unit Base Unit Factor UNIT command parameter
English Kip (kilopound) Kip 1 KI
Pound Kip 0.001 PO
Metric Kilonewton Kilonewton 1 KN
Decanewton Kilonewton 0.1 DN
Newton Kilonewton 0.001 NE
Meganewton Kilonewton 1,000 MN
Metric Ton Kilonewton 9.80665 MT
Kilogram Kilonewton 9.80665 (10)-3 KG

Example

UNIT KIP FT
UNIT INCH
UNIT METER KNS
UNIT CM MTON

Notes

  1. A UNIT command may be inserted before any primary level command (e.g., JOINT COORD, MEMBER INCIDENCE, etc.).
  2. If no UNIT command is specified, then the default units are taken as:
    • Length: feet
    • Force: kips
  3. Units can be mixed between systems of units, such as length of feet and force of kilonewtons.
  4. Units that include both length and force components (e.g., stress = force/length2) will be constructed from the current length and force units.

    Thus, if the current length unit is feet and force unit is kilonewtons, then when defining Young's modulus, the value for a stress unit is kN/ft2. While this may be an odd definition, it is fully supported by STAAD.Pro.

  5. Kilograms and metric tons are mass units which are converted to units of force assuming an acceleration due to gravity of 32.174 ft/s2.
  6. Temperature units are not explicitly defined in STAAD.Pro. The value of temperature laoding and coefficient of thermal expansion are taken to be consistent units.