(no lateral bracing specified) = 3

Introduction to Wood Design
38 × 184 mm sloping rafters are untreated
and belong to the Spruce-Pine-Fir group. They
will be seasoned and the service conditions
will be dry.
Design the heel joint between the 38 × 184 mm
and two 38 × 235 mm members using nails.
heel Connection
Try 3in (76 mm) long common round
wire nails
diameter = 3.66 mm
Required penetration in the head side
member is 3d F.
3 × 3.66 = 11 mm < 38 mm
Required penetration in the point side
member is 5d F.
5 × 3.66 = 18 mm < 38 mm
Design for lateral strength resistance
Factored tensile force, N f
N f = 2500 N
Factored resistance, N r
where
N r = ϕN un F n sJ F
ϕ = 0.8
N u = n u(K D K SF K T)
n u = unit lateral strength resistance per
nail or spike, N
n F = number of fasteners in
the connection
n s = 1 (nails are in single shear)
J F = J eJ AJ BJ D
J e = 1.0 (nails are driven into side grain)
J A = 1.0 (nails are not toe nailed)
J B = 1.0 (nails are not clinched)
J D = 1.0 (not used in diaphragm
construction)
J F = 1.0 × 1.0 × 1.0 × 1.0
= 1.0
11-63
unit Lateral Strength Resistance
The penetration depth of the nail is 76 mm
(3 inch), therefore this is a two member
wood to wood connection.
For two-member connections, only Items (a),
(b) and (d) to (g) of the yield equations are
considered valid.
where
t 1 = 38 mm
d F = 3.66 mm
f 2 = 50G(1 – 0.01d F)
= 50 × 0.42 × (1 – 0.01 × 3.66)
= 20 MPa
G = 0.42 (CSA O86, Table A. 10.1)
t 2 = 38 mm
f 3 = 110G 1.8 (1 – 0.01d F)
= 110 × 0.42 1.8 × (1 – 0.01 × 3.66)
= 22 MPa
f y = 50(16 – d F)
= 50 × (16 – 3.66)
= 617 MPa
For lumber side plates:
f 1 = 50G(1 – 0.01d F)
= 20 MPa
(a) f1dFt1 = 20 × 3.66 × 38
= 2814 N
(b) f2dFt2 = 20 × 3.66 × 38
= 2714 N
(d) f 2 c
1dF 1
6 (f
f3
fy
+ f) f
1 t1
+ m
5 d
1 3
= 20 × 3.66 2 ×
1 22 617 1 38
c # # + # m
6 (20 + 22) 20 5 3.66
= 996 N
1
F