6-1: a square box beam is made of two 20*80-mm planks and two-20*120-mm planks nailed together as shown. knowing that the spacin between the nails is s= 50 mm and that the allowble shearing force in each mail isa 300 N , determine (a) yhe largest allowble vertical shear in the beam ,(b) the corresponding maximum shearnog stress in the beam
solution : Fnail= 300 N F nail= T*t*s (T=shearing stress) T=(300/50*10^-3*20*10^-6)
between the nails is s= 50 mm and that the allowble shearing force in each mail isa 300 N , determine (a) yhe largest allowble
vertical shear in the beam ,(b) the corresponding maximum shearnog stress in the beam
F nail= 300 N
F nail= T*t*s (T=shearing stress)
T=(300/50*10^-3*20*10^-6)
T=3*10^5 N/M
I=(2*20*80^3*10^-12/12)+2((120*20^3*10^-12/12)+20*120*10^-6*(50*10^-3)^2)
I= 1.3866*10^--5
Q=A*Y'
Q=20*120*10^-6*50*10^-3
Q=1.2*10^-4
s=I*t*T/Q
s=1.386 KN
b):
T max=1.5*(S/A)
= 1.5(1.386*1000/??????)