Project Notes

Sample House Component Check

3. Check a rafter for bending. (see beam homework from chapter 6)

Loads
(horizontal, not at 4:12) w_D = 14 lb/ft
w_Lr = 27 lb/ft
w_S = 24 lb/ft

Load combination needs to be determined

Span L = 14 ft (assume horizontal span)

Trial member size 2x8

Stress grade and species No. 2 Spruce-Pine-Fir

Spacing 16 in. OC

Unbraced length l_u = 0

Moisture content MC ≤ 19%

Deflection limits 0.93 in. for L
0.93 in. for S
1.4 in. for (D + L), or (L + 0.5D) if under dry conditions

Dry-service conditions

Normal temperatures

Bending about strong axis

Loads (horizontal, not at 4:12)	w_D = 14 lb/ft w_Lr = 27 lb/ft w_S = 24 lb/ft
Load combination	needs to be determined
Span	L = 14 ft (assume horizontal span)
Trial member size	2x8
Stress grade and species	No. 2 Spruce-Pine-Fir
Spacing	16 in. OC
Unbraced length	l_u = 0
Moisture content	MC ≤ 19%
Deflection limits	0.93 in. for L 0.93 in. for S 1.4 in. for (D + L), or (L + 0.5D) if under dry conditions
Dry-service conditions
Normal temperatures
Bending about strong axis