Week 2 Challenge
S.No-1
Aim:To Calculate the net section area for the tension member.The plate size is 260 x 20 thick and Bolt size is 20 mm.
Calculation:For Plate-Drilled hole
Given bolt size 20mm dia
hole dia=20+2
=22mm
b=260mm;t=20mm;n=4 and hole dia=22mm
Net Area=(b-(nxhole dia)xt)
=(260-(4x22)x20)
=3440mm^2
For Plate – Zigzag bolting
Failure paths 1)AD,BF 2)CEG 3)ACEG 4)BCEG 5)ACF,BCD 6)BCF 7)ACD
1)NET AREA FOR AD,BF
Net Area=(b-(nxhole dia)xt)
No. of holes(n)=2
=(260-(2x22)x20)
=4320mm^2
2)NET AREA FOR CEG
Net Area=(b-(nxhole dia)xt)
No. of holes(n)=3
=(260-(3x22)x20)
=3880mm^2
3)NET AREA FOR ACEG
Net Area=[(b-(nxhole dia))+(∑">∑(p^2)/4g)]xt
No. of holes(n)=4
Staggers=1
=[(260-(4x22))+((60^2)/(4x60))]x20
=3740mm^2
4)NET AREA FOR BCEG
Net Area=[(b-(nxhole dia))+(∑">∑(p^2)/4g)]xt
No. of holes(n)=4
Staggers=1
=[(260-(4x22))+((50^2)/(4x60))]x20
=3649mm^2
5)NET AREA FOR ACF AND BCD
Net Area=[(b-(nxhole dia))+(∑">∑(p^2)/4g)]xt
No. of holes(n)=3
Staggers=2
=[(260-(3x22))+((60^2)/(4x60) +(50^2)/(4x60))]x20
=4389mm^2.
6)NET AREA FOR BCF
Net Area=[(b-(nxhole dia))+(∑">∑(p^2)/4g)]xt
No. of holes(n)=3
Staggers=2
=[(260-(3x22))+(2X(50^2)/(4x60))]x20
=4297mm^2
7)NET AREA FOR ACD
Net Area=[(b-(nxhole dia))+(∑">∑(p^2)/4g)]xt
No. of holes(n)=3
Staggers=2
=[(260-(3x22))+(2X(60^2)/(4x60))]x20
=4480mm^2.
BCEG IS CRITICAL LINE.
Angle (200 x 100 x 12 with M20 bolt)
g*=70+60-12=118mm
Ag(L200x100x12)=3480mm^2
path ABC
Net Area=[(b-(nxhole dia))+(∑">∑(p^2)/4g)]xt
=[(3480-(3x22))+((50^2)/(4x90) +(50^2)/(4x110))]x12
=2541mm^2
Path AC
Net Area=[(b-(nxhole dia)]xt
=(3480-(2x22))x12
=2952mm^2
Hence ABC is critical line.
Result:
For Plate-Drilled hole Net Area=3440mm^2
For Plate – Zigzag bolting Critical line is BCEG with area 3649mm^2
Angle (200 x 100 x 12 with M20 bolt)
Critical line is ABC with area 2541mm^2.
S.No-2
Aim: To design a sag rod.Purlins are supported at 1/3rd points by sad rod.
Introduction:
centre to centre distance of Rafter spaced at 8 m
spacing of purlin = 1.2 m,
Self weight of roofing (including thermal insulation)= 60 kg/m2 ,
Wind pressure intensity = 150 kg/m2,
Slope of rafter = 15 degrees, Live Load =75 kg/m2 and self weight of purlin as 100 kg/m.
Calculation:
Load on purlins,
Gravity componants=60x1.2+75x1.2+100
=262kg/m
=2.57KN/m
Parallel of roof componant =2.57xsin15
=0.67KN/m
Pull on Sag rod=(0.67x(1/3)x8)
=1.79KN
Factored load=1.5x1.79
=2.69KN
Required Net AREA= From Clause 6.3.1
An=((2.69x10^3)x1.25)/(0.9x410)
=9.112mm^2.
Provide 12mm sag rod
(π">π/4)x12^2=113.1mm^2(unthreaded)
84.3mm^2(threaded)
Hence safe.
S.No-3
Aim:To Design a single angle member of length 5m to carry axial tensile force of 500 kN. Yield strength fy of the material to be considered is 350 N/mm2.
Calculation:
Area required=(1.1x500x1000)/250
=2200mm^2
choose (200x100x10) area is 2920mm^2
Yield strength gross section=(250x2920)/1.1
=664KN>500KN.
Net rupture section from clause 6.3.3 from IS800:2007
An=(((200-(10/2))-(3x22))x10)+(100-(10/2))x10)
=2240mm^2
Tdn=(αxAnxFu)/γm1
=(0.8x2240x410)/1.25
=588KN>500KN
Block shear failure
From clause 6.4.1 from IS800:2007
Tdb1=553KN
Tdb2=548KN
min{Tdb1,Tdb2}=548KN>500KN
Slendernous check=L/r=5000/21.7=230<400
Result: Hence safe