|
|
|
|
|
The force offset is the distance between the end of a wall segment and where the hold-down force is situated or the force at the compression end is assumed to act.
These offsets are used to calculate the moment arm used for overturning calculations and for the calculation of shear wall deflection due to the rotation caused by vertical displacement of the hold-down device.
The tension force is located at the inner face of the end studs plus the hold-down anchor bolt center line location for the hold-down model from the hold-down database.The compression force is assumed to be located at the center of the end stud pack.
Note that O86 11.6.4.1 requires that you use the centre of the end studs as your hold-down offset for moment arm calculations at both ends, however using the location of the hold-down anchor bolt is more accurate and slightly conservative when compared to the centre of the wall studs.
When anchorages are used instead of hold-downs, the location is the end of the wall studs plus 2", which is sufficient space to comfortably place a 3" x 3" washer. In addition, when calculating the moment arm, the program imposes a 300 mm minimum on the total offset from both ends of the wall, to comply with O86 11.6.4.1.
In the Hold-down Settings, you can choose to override these values with a fixed distance from the end for all hold-down and compression forces in the structures.
For Non-wood/proprietary walls, the offset is the fixed distance input in the Hold-down Settings, as there are no hold-down devices assigned to these walls and no assumptions made about the composition of the wall end chords.