Shrinkage

Shrinkage

Refers to the wood shrinkage that occurs between fabrication and service of the perpendicular-to-grain wood members spanned by the hold-down.

It is calculated when the hold-down does not include a shrinkage compensating device.

Calculation

The vertical shrinkage displacement is 0.002 x (% fabrication moisture content – % in-service moisture content) x shrinkage length for that building level from the Structure input view.

Moisture content input

The fabrication and in-service moisture content are input in the Design Settings. If deflection analysis is not activated you can input only whether it was greater or less than 19% (fabrication) or 15% (in-service), for use in nail withdrawal design. For deflection analysis the actual moisture content is input.

In- service greater then Fabrication

If for some reason in service moisture content is greater than fabrication, shrinkage is set to zero.