Report

Engineering with Wood Shear Walls and Diaphragms Why Buildings Don’t Fall Over Presenters: David W. Boehm, P.E. Gary Sweeny, P.E. Plan View Assume seismic load is also 200 plf l = 120’ veu wew= b=40’ 200#/FT vns wns = 200#/FT DIAPHRAGM UNIT SHEARS vew = wew x b = 200 x 40 2 x 120 = 33 #/FT = 200 x 120 2 x 40 = 300 #/FT 2xl vns = wns x l 2 xb PANEL LAYOUT AND FASTENER SCHEDULE North-South Loading Case 1 v = 300 #/FT Assume 8 d nails 15/32 plywood 2” nominal framing Choose: Blocked Diaphragm 8 d nails @ 4” panel edges 8 d nails @ 6” interior East-West Loading Case 3 v = 33 #/FT Unblocked 6” max spacing at panel edges DIAPHRAGM CHORD SIZE Moment due to N-S wind m = wl 2 = 200 1202 = 360,000 FT-LBS 8 8 Axial load in chords = C = T = M = 360,000 ft-lbs = 9,000 LBS b 40 ft Assume allowable ft = 1150 psi Area required = 9,000# = 7.8 in2 1150 psi Assume 2 x 8 wall plate, bolted Area of 2 x 8 with bolt hole A = 1.5 x (7.25 - .875) = 9.56 in2 Use double 2 x 8 top plate / chord to allow for splice Diaphragm layout Shear Walls North wall v=33 #/ft Nominal nailing required East and west walls v=300 #/ft Vns = 300#/ft(40’) = 12000# 20’ 40’ T Nailing pattern 7/16 sheathing 2 x studs 8d nails @ 4” required A C Shear wall elevation Tiedown Force ΣMA = 0 0 = (12000 x 20) – (T x 40) T = 6,000# WALL DESIGN WITH OPENINGS DRAG STRUT / COLLECTOR FORCE OVERTURNING FORCE