Week 2 Challenge
Q.1 Aim and Introduction- design of tension member
. Net Area for tension member calculation problem
Data given: Plate size : 260 x 20 mm
Bolt size : 20mm
No of bolts : 4
Procedure : chain bolting for 20 mm bolt hole dia = 22mm
Net area = `b - nd)t`
=`(260-4x22)20
=3440mm2
Result : Net area for chain bolting is 3440mm2
zig zag bolting
Staggared length correction= `p2/4g`
Path AD and BF(two bolts):
Net area = (260 - 2x22) x 20
= 4320mm2
Path CEG (three bolts):
Net area = (260 - 3x22) x 20
= 3880mm2
Path ACEG (four holes one stagger bolts):
Net area = (260 - 4x22 +60^2/4x60) x 20
= 3740mm2
Path BCEG (four holes one stagger bolts):
Net area = (260 - 4x22 + 50^2/4x60) x 20
= 3648mm2
Path ACF and BCD (three holes two stagger bolts):
Net area = (260 - 3x22 +60^2/4x60+50^2/4x60) x 20
= 4388mm2
Path BCF (three holes two stagger bolts):
Net area = (260 - 3x22 +2x50^2/4x50) x 20
= 4380mm2
The minimum net area is for path BCEG (four holes one stagger bolts)
Result : Net area for zig zag bolting is 3648mm
Angle (200 x 100 x 12 with M20 bolt)
for an M20 d=22mm
for net area calculation the angle may be visualized as being flattened into plate as shown in fig.
g*= g1 + g2 - t =( 70 + 60 - 12)=118
Path ACE=(200+100 - 3x22)12+ 100^2/4x90+ 50^2/4x118
= 2808 +27.78+5.3
=2841mm
result = net area calculated is 2841 mm.
2 Aim and introduction_ Design of sag rod
Procedure: DATA GIVEN : Dead load from roofing=60kg/m2
self wt of purlin=100kg/m
Live load= 75kg/m2
wind load= 150kg/m2
panel size= 2.67x1.2m
total dead load=60/2.67+100=122.47kg/m
Live load = (75/2.67)=75/2.67=28.1 kg/m
total gravity load=122.47+28.1=150.57 kg/m
component of gravity parallel to roof =150.57 x sin15=80.23kg/m
Pull in sag rod = 80.23x2.67=214.22kg
Factored load=1.5 x 214.22=321.34kg
Required net area=`(T X`1.25 / 0.9xfu)`
=321.4x1.25/0.9x410
=1.1mm2
Result : hence provide a 16 mm diameter sag rod
3. Aim and Introduction- Determine section size for given tensile load
Procedure : Data given Axial tensile force = 500 kn
member length= 5 m
yield stress fy = 350n/mm2
solution : Approx required area= 1.1x 500x10^3/350=1571.43mm2
Choose 125 x75 x8 angle section having 17.11cm2
Gusset is connected to 125 mm leg of the angle. g = 60 mm M 16 bolt
Net area of connected leg A nc=(125- 8/2 -18)x8=824 mm2
Net area of outstanding leg is Ago = (75-8/2 )x8=568 mm2
Ag gross area = 1711 mm2
(a) Strength governed by yielding of gross section =Ag x fy/partial safety factor
=(1711 x 350/1.10)
=544.41 mm2
(b) Strength governed by rupture of critical section=......0.9x ((824+568)x 350/1.25
=350.784 kn
(c) Strenght governed by block shear=
check for stiffness
Result :