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Wood tension element capacity calculator

Jonathan Ochshorn

© 2009 Jonathan Ochshorn.

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Directions: Enter values for species, grade, cross section, and bolt geometry (for regular bolt grid only; staggered bolt geometries cannot be used in this calculator). Enter "load of shortest duration" to adjust allowable stresses for "duration of load." For live and dead load only, enter "live load." Wet service conditions only matter for allowable shear (in tear-out calculations). Bolts, if any, are normally inserted through the smaller cross-sectional dimension, t (in which case the question, "bolt length = t?" is answered, "yes"). Cross sections are checked for tension capacity on the net area and, if desired, for row and group tear-out. It is assumed that the tension force is applied parallel to grain.

Bolt geometry and bolt capacity (see Fig. 1) are not checked; however, bolt spacing and end/edge distances that do not comply with NDS-2005 guidelines are noted.

Press "update" button.

More detailed explanations and examples can be found in my text.

species	section	no. of rows (Rn)	bolts per row (n1)
Douglas Fir-Larch Douglas Fir-Larch (North) Douglas Fir-South Hem-Fir Hem-Fir (North) Spruce-Pine-Fir Spruce-Pine-Fir (South) Southern Pine	2x4 2x6 2x8 2x10 2x12 2x14 4x4 4x6 4x8 4x10 4x12 4x14 4x16 6x10 6x12 6x14 6x16 6x18 6x20 8x12 8x14 8x16 8x18 8x20 10x14 10x16 10x18 12x16 12x18 12x20 14x18 14x20 16x20 6x6 6x8 8x8 8x10 10x10 10x12 12x12 12x14 14x14 14x16 16x16 16x18 18x18 18x20	0 1 2 3 4 5 6	0 1 2 3 4 5 6 7 8 9 10 11 12
grade	tension force	bolt diameter	wet service?
Select Structural No. 1 No. 2 No. 3 Misc.		1/4 in. 3/8 in. 1/2 in. 5/8 in. 3/4 in. 7/8 in. 1 in.	yes no
	lb kips
load of shortest duration	bolt length = t?	space betw rows (in.)	Scrit (in.)
Dead load, D Live load, L Snow load, S Construction load, Lr Wind or seismic load, W or E Impact load, I	yes no	1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.5 4.75 5	1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.5 4.75 5
check for row and group tear-out?	governing capacity
yes no
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Checks:
errors:
grade doesn't exist
force must be > 0
net area must be > 0

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Disclaimer: This calculator is not intended to be used for the design of actual structures, but only for schematic (preliminary) understanding of structural design principles. For the design of an actual structure, a competent professional should be consulted.

First posted August 6, 2009 | Last updated August 6, 2009