Hold-down Connection Assembly

Hold-downs connect the wall end studs on an upper level to either the corresponding stud on a lower level or anchored to the foundation. Continuous tie rod systems extending over multiple building levels are not included in this version of Shearwalls, but will be in the next major release of the program.

Vertical Connection

Hold-downs include either an anchor bolt or threaded rod which connects upper and lower brackets or straps, or a continuous strap extending from upper to lower level. All the hold-downs in the current standard database contain an anchor bolt and do not rely entirely on a metal strap.

Horizontal Fasteners

The connection from bracket or strap to the upper and lower studs is made via bolts, screws, or nails. The hold-down capacity and displacement values apply to the entire hold-down assembly, including these fasteners, so although the fastener details are published by the manufacturer, they are not included in the Shearwalls database.

Single or double bracket

Hold-downs are designated in Wall or Opening input view as being either single-bracket or double bracket, indicating that the hold-down has a bracket or strap on one floor or both. By default, hold-downs on the ground level are single-bracket, and upper-level hold-downs are double-bracket.

The displacement data in the hold-down database apply to just one bracket or strap of a hold-down. In the Shearwalls program, hold-downs designated as double-bracket have the displacement values doubled, and the maximum anchor bolt length is also doubled. The capacity data apply to each bracket of the hold-down, and are never doubled.

Continuous Strap

There are no hold-downs in the initial database consisting of one continuous strap without an anchor bolt; however it is possible to add this type of hold-down to the database. When creating a hold-down in the database with a continuous strap, you can either

• enter hold-down data that apply to the elongation of the entire strap and the total number of fasteners, top and bottom, and designate it as single-bracket in Wall or Opening input view.
• enter hold-down data that apply to the elongation of ½ the strap, and the fasteners on one level, and designate it as double-bracket in Shearwalls in Wall or Opening input view. .

Shrinkage Compensating Device

You can designate that the hold-down includes a mechanical device to adjust for the shrinkage of the perpendicular-to-grain wood between the extreme hold-down fasteners, so that such shrinkage is not included in the calculations for shear wall deflection.