Problem 1: Roof Framing Plan with Seismic Loads shown Wr= 250 plf \'Plywood Layo
ID: 1711864 • Letter: P
Question
Problem 1: Roof Framing Plan with Seismic Loads shown Wr= 250 plf 'Plywood Layout 2" nominal lumber roof trusses @ 24" o.c. 15'-0 25-0" 20'-0 20'-0" 80-0 15/32" thick 24/0 span rated, Sheathing and Single-Floor OSB with 10d nails. Walls are 14 feet tall with 2x studs at 16" on center Note: Maximum distance from the end of the wall for anchor bolts is 12", and the maximum spacing of anchor bolts is 6 feet on center (IBC 2308.6) Given: Required: Roof diaphragm shear, V and unit shear v for transverse direction (wr). Is blocking required for the lateral forces? If blocking is needed, when can it be omitted? a. b. c. Unit wall shear in the West Wall d. Using 15/32" Wood Structural Panels (not Structural I) with 10d nails, find the required nailing. Determine if 3x members are required and where. e. Determine the 1/2" diameter anchor bolt spacing in 2x sill plate for the West Wall. f. Unit wall shear in the East Wall . Using 3/8" Structural I sheathing, find the required nailing. Can the values for 15/32 be used per footnotes? Determine the 1/2" diameter anchor bolt spacing in 2x sill plate for the East Wall. h.Explanation / Answer
Ans.
•Diaphragm load is distributed to shear walls based on relative stiffness of shear walls and diaphragm
Wind nominal unit shear capacity vw
IBC allowable stress design value x 2.8
Seismic nominal unit shear capacity vs=vw/1.4
ASD unit shear capacity, vs=250/2=125plf
Where, 2=ASD reduction factor
LRFD unit shear capacity, vs=250*0.8=200plf
Where, 0.8=LRFD resistance factor
Reduced nominal unit shear capacities determined
by multiplying the tabulated nominal unit shear
capacity by the Specific Gravity Adjustment Factor
*SG Adjustment Factor = [1.0-(0.50-G)] < 1.
Diaphragm
bending shear nail slip chord connection slip
Total= b+ v+ n+ c
= 5vL3/8EAb + vL/4GT + 0.188Len + (cX)/2b
SDPWS – nails
unblocked and
blocked
Shear panel deformation and nail slip
vL/4GvTv + 0.188Len 0.25 v L /1000Ga