This page contains frequently asked questions related to units.
FAQ
In which units is the mass entered?
As per CSI Analysis Reference Manual, chapter "Joints and Degrees of Freedom", section "Masses", the mass values must be given in consistent mass units (W/g). Also please note that the program uses force, length and temperature as primary units, while the mass is secondary unit. Based on this the following reasoning is made:
(1) If the "Ton, m, C" set of units is chosen, the "ton" actually represents ton-force (tonf).
(2) The mass of 1 tonm (1000 kg) has a weight of 1 tonf (9810 N).
(3) However, the mass must be entered into the program in consistent units (W/g as mentioned above), therefore the mass corresponding to 1 tonf weight (remember that the weight is the primary unit) would be entered as W/g = 1 tonf / (9.81 m/s^2) = 0.102 tonf * s^2 /m.
Related Incident:
- Unknown macro: {incident}
The following explanation is provided in Incident 30267: In SAP2000, the basic units are Force (lb, kip, N, kN, etc.), Length (ft, in, m, mm, etc.), Time (second), and Temperature (F, C). Mass is a derived unit and SAP2000 does not use lb or kip for mass units, they are only used for force units. Weight has units of F, where F is force. CONSISTENT mass units are given by F/(L/T^2), where L is length, T is time, and the mass units are simply force divided by UNIT acceleration.