Use of larger numbers in joint coordinates in STAAD.Pro models

Applies To
Environment: ALL
Area: Modeling Solutions
Subarea: Geometry
Original Author:Sye Chakraborty, Bentley Technical Support Group


I am working with a STAAD.Pro model where the joint coordinates are very large numbers as these are the actual site coordinates. I would like to know if there are any recommendations regarding this.


Occasionally one may run into STAAD.Pro models with large values of joint coordinates. These mainly happen when users are using the actual site coordinates or are importing the model from other applications into STAAD.Pro, in which actual site coordinates were used to create the model. Our recommendation in such cases is that the model origin in STAAD.Pro be moved close to the model so that the numbers associated with the coordinates are no more than 7 significant digits. This is because of the fact that otherwise inaccuracies may creep in due to rounding off of significant digits. The errors are more significant when larger units of length are used. For example if these site coordinates are entered in miles, even a round off of 0.001 (in miles) would mean that there is a significant inaccuracy of 5.28 ft or 63.36 inches introduced due to that. One should therefore move the model origin in such cases using the option shown next, so that the model coordinates are reduced to much smaller numbers


Another thing to remember here is that for models having larger values of Joint Coordinates, it is advisable to increase the number of significant digits to a higher number than the default of 6. That allows more digits before and after the decimal to be accounted for, thereby improving the accuracy. The significant digits can be set from within the Configuration option which can be accessed from the backstage, as shown in the next picture