Wood Compression Results

Data

Compression Parallel to Grain
	type of wood:	2"x3" SPF (spruce-pine-fir) stud select
	specimen length:	8.00 in		gage length:	6 in
	specimen width:	1.50 in		speed:	0.024 in/min
	specimen thickness:	2.50 in		tested at:	74 F, 48% MC
Compression Perpendicular to Grain
	type of wood:	2"x3" SPF (spruce-pine-fir) stud select
	specimen length:	5-15/16 in		bearing plate width:	2.013 in
	specimen width:	2.50 in		speed:	0.012 in/min
	specimen thickness:	1.51 in		tested at:	74 F, 49% MC

Parallel-to-grain specimen initially failed by crushing and then split through a knot.
Perpendicular-to-grain specimen began cracking through pith.

Compression Results

Compression Modulus (psi)

	IDE 120 Laboratory Value	Reference Laboratory Value1	Percent Difference	Reference Design Value2	Percent Difference
Parallel to Grain	2,170,000	1,500,000	37%	1,000,000	74%
Perpendicular to Grain	45,600	75,0003	49%	58,000	24%

1. reference laboratory values for white fir
2. reference design values for spruce-pine-fir
3. E_T = 5.2140 E_L ^6.7490E-1 (Wood Structures - A Design Guide and Commentary, ASCE, 1975)

Compressive Strength (psi)

	IDE 120 Laboratory Value	Reference Laboratory Value1	Percent Difference	Reference Design Value2	Percent Difference
Parallel to Grain	5300	5800	9%	625	158%
Perpendicular to Grain	1200	530	77%	335	113%

1. reference laboratory values for white fir
2. reference design values for spruce-pine-fir

 

Buckling

If

E = 2,170,000 psi
I = (2.50 in)(1.50 in)³ / 12
L_e = 2(8.00 in)

then

P_cr = 58,800 lb