Continuous Tie-downs ("Aussie" Tie-downs)

The following table gives capacities for "continuous tie-downs". This type of tie-down is generally used for multi-story wood-frame construction, but has clear advantages for single-story buildings as well (see Appendix A of the Shear Wall Construction Guide). The Building Code of Australia (BCA) gives sizes for threaded rods to use as continuous tie-downs in its prescriptive shear wall requirements. This is the first code we are aware of to do this, hence the term "Aussie" tie-downs.

All-thread Diameter (inches)	Allowable Force (pounds)	Plate Washer Size (inches)			Post Area (square inches)
		Width	Length	Thickness
3/8	2,700	3	1-1/2	1/4	7
1/2	4,900	3	2-3/4	3/8	12.25
5/8	8,100	3	4-1/2	5/8	20
3/4	11,700	5	4	5/8	29
7/8	16,000	5	5-1/4	3/4	40
1	20,900	5	6-3/4	1	51.7
1-1//8	26,500	5	8-1/2	1-1/8	65.5
The above table is based on the following: ASTM A36 steel rod, with an allowable stress increase of 33 percent for earthquake loading. Plate washer size is determined based on side-grain crushing of the wall top plate with an allowable stress (FCperp) of 625 psi (Douglas Fir) Plate washer thickness is based on ASTM A36 steel with an allowable stress increase of 33 percent Post Area is determined based on side-grain crushing of the foundation sill (mudsill) with an allowable bearing stress of 405 psi (Hem-Fir)

Thor Matteson, Structural Engineer

California License #S4097
Residential and Commercial Earthquake Retrofit Designs,
Structural Evaluations, & Related Engineering Services