Week 2 Challenge
1)Net Area for tension member calculation :
- plate - Drilled hole
b breadth = 260mm
d depth = 20mm
d0 = 20 - 2 = 18mm
t= 20mm
number of bolts = ((b - 2 x e ) /p) + 1
p = 2.5d = 2.5 x 20 = 50
e = 1.5d = 1.5 x 20 = 30
No of bolts = ((260 - 2 x 30)/50) + 1
No of bolts = 6
Net section area = (b - nd0 )t
Net section area = (260 - 6 x 18) 20
Net section area = 3000 mm^2
b) plate - zigzag bolting
b = 260mm
d=20mm
d0 = 20 - 2 = 18mm
t=20mm
No of bolts = ((b - 2 x e)/p) + 1
p = 2.5d = 2.5 x 20 = 50
e = 1.5d = 1.5 x 20 = 30
No of bolts = ((260 - 2 x 30)/50) + 1
No of bolts = 6
Net section area = (b - nd0 )t
Net section area = (260 - 6 x 18 ) 20
Net section area = 3000 mm^2
ANGLE (200 X 100 X 12 WIDTH WITH M20 BOLT)
b = 200mm
d =20mm
d0 = 20-2 = 18mm
t=12mm
No of bolts = ((b - 2 x e)/p) + 1
p = 2.5d = 2.5 x 20 = 50
e = 1.5d = 1.5 x 20 = 30
No of bolts = ((200 - 2 x 30)/50) + 1
No of bolts = 6
Net section area = (b - nd0 )t
Net section area = (200 - 6 x 18 ) 20
Net section area = 1840 mm^2
2) SAG ROD DESIGN PROBLEM:
F = 5/8 X w x sin0 x s x 4
F = 5/8 x 100 x 9.81 x sin15 x 8 x 4
F = 5061.96 N
AREA = F/fy
pi x d^2 = 5061.96 / 0.6 x 250
d = 6.5mm
3) Determine section size for given tensile load
assume 4 mm weld size , fy = 250 MPa,
fu = 410 Mpa
approximate gross area = 1.1Tdg/fy = 1.1 x 250 x 1000/250 = 1100 mm^2
from steel table ,select ISA 100x75x8mm connected to gusset plate by longer length Cxx = 31mm
area of connected leg = (100 - 8/2) x 8 = 768 mm^2
area of outstanding leg = (75 - 8/2) x 8 = 568 mm^2
Ag = 768+568=1336mm^2>,hence ok
design strength due to yielding of gross section,
Tdg = Agfy/rm0 = 0.91 x 1336 x 250 / 1000 = 303.94kn
design strength due to rupture at net section,
Tdn = a An fu/rm1
Tdn = 0.8 x 1336 x410/1000
Tdn = 438.21 kn
design strength due to block shear,
for calculating of block shear , length of weld reqiured
P1 X 100 =250 X (100-31)=172.50 kn
P2 = 250-172.50 = 77.5 kn
strength of 4mm weld = 0.7 x 4 x 0.462 x 410 = 530.37 kn/mm
effective length of weld on head side = 172.5 x 1000/530.37 = 325 mm
effective length of weld on toe side = 77.5 x 1000/530.37 = 146 mm
Total welded length = 325 + 146 = 471mm
Avg = Avn = 471 x 8 = 3768 mm^2
Atg = Atn = 100 x 8 = 800 mm^2
Tdb1 = 0.525Avg x fy + 0.72 x Atn x fy
=0.525 x 3768 x 250 /1000 + 0.72 x 800 x 410 /1000 = 730.31kn
Tdb2 = 0.416 Avn x fu + 0.91Atg fy
=0.416 x 3768 x 410 / 1000 + 0.91 x 800 x 250 / 1000 = 438.21 kn
tensile strength provided = 438.21kn,303.94kn and 730.71KN > 250KN
hence safe