DESIGN OF SIGN BOARD GANTRY

20.2 m Span
2.0 DESIGN OF COLUMN

Max axial force P = 76.00 kN

Moment My = 0.3 kN-m (Critical Load
Moment Mz = 0.26 kN-m combination DL+W
Length of member L 5.4 m
Effective Length Leff = 8.1 m
Increase in Permissible Stresses = 3%

Properties of pipe section

Outer diamter of pipe = 168.3 mm
Inner diamter of pipe = 150 mm
Moment of Inertia I = 4.200E+07 mm4
Area of Section A = 6883 mm2
Section Modulus Z = 383000 mm3
Radius of gyration r = 73.3 mm

Slenderness ratio Leff/r = 110.50 <

From IS:806, Table-2 Leff/r sc
110 81.3
120 72.1
Permissible axial stress in compression Fa = 80.84 N/mm2
Permissible bending stress in extreme Fb = 165.5 N/mm2
fibre in tension and compression
Calculated axial stress (fa ) P/A = 11.04 N/mm2

Calculated Bending stress in extreme My 2 Mz 2

f = +
fibre Z Z
= 1.04 N/mm2
fa/Fa = 0.133
f/Fb = 0.006

fa/Fa + f/Fb = 0.139 <

 (Critical Load
combination DL+WL)

250 OK

(Table-3, IS:806)

1 OK
4.0 DESIGN OF BASE PLATE

Vertical load on column P = 76 kN (From STAAD)

Transverse Moment MT = 106.4 kN-m
Longitudinal Moment ML = 0.96 kN-m

Total vertical load on column base plate = 76.00 kN

Total transverse moment on column base plate = 106.4 kN-m
Total longitudinal moment on column base plate = 0.96 kN-m

Assuming the size of base plate LxB = 1700 x 1000 mm

Thickness of plate = 16 mm
Area of cap plate A = 1700000 mm2
Section modulus ZT = 283333333 mm3
Section modulus ZL = 481666667 mm3

Maximum bearing pressure, w = 0.422 N/mm2

Projection, A = (850-300) / 2
= 275 mm

Projection, B = (1000-300) / 2
= 350 mm

Partial safety factor againest yield stress and buckling, γ m0 = 1.1 (Table-5, IS 800-2007)

Characteristic yield stress, fy = 250 N/mm2

Thickness of Base plate, t = (2.5w/fy)*(A2 -0.3B2)*γm0

= 13.4 mm < 16
SAFE

Provide a base plate of 1700 x 1000 x 16

5.0 DESIGN OF ANCHOR BOLTS

Diameter of bolt d = 20 mm
Diameter of bolt hole d0 = 24 mm

Thickness of base plate t = 16 mm

Edge distance of the bolts e = 75 mm
Pitch of the bolts p = 225 mm

Total number of bolts n = 20

For M20 bolt of Grade 4.6
Ultimate tensile stress of bolt fub = 400 Mpa
Yield stress of bolt fyb = 240 Mpa

For Fe 415 (E 250 plate)

Ultimate tensile stress of the plate fu = 410 N/mm2
Yield stress of plate fy = 250 N/mm2

Partial safety factor against yield stress γm0 = 1.1

γmb = 1.25
Partial safety factor for bolted connection
with bearing type bolts

1700

1000

75

225 225

(a) Shear Capacity of Bolt

Design Strength of bolt, Vdsb = Vnsb/γmb

where Vnsb = (fub/ 3)x(nnAnb+nsAsb)

Net shear area of bolt at threads Anb = 245.04 mm2

Nominal plain shank area of bolt Asb = 314.16 mm2
Number of shear planes at thread nn = 1.00 per bolt
Number of shear planes at shank ns = 0.00 per bolt

So, total nn = 1.00 & total ns = 0.00

 Vnsb = 51.29 kN

Design strength in shear, Vdsb = 41.03 kN

(i) Long joints
If
lj > 15d
lj = 675 mm > 300 mm
So,
Vdb = Vdsb x β1j
where β1j = 1.075-0.005(lj/d)
= 0.90625
0.75≤β1j≤1.0 OK

(ii) Large grip lengths

If
lg > 5d
Vdb = Vdsbxβlg
where βlg = 8d/(3d+lg) = 8/(3+lg/d)
βlg < β1j
& lg < 8d

(b) Bearing Capacity of Bolt

Design bearing strength of bolt, Vdpb = Vnpb/γmb
where Vnpb = 2.5 kb d t fu

kb smaller of e/3d0 = 1.0417

(p/3do)-0.25 = 2.8750

fub/fu = 0.976

1 = 1

kb = 0.9756
Vnpb = 320 kN

Design strength in bearing, Vdpb = 256 kN

Design strength of joint Vdb = smaller of Vdsb = 41.03 kN

Vdpb = 256 kN

Vdb = 41.03 kN
(c) Tension Capacity of Bolt
Factored tensile force = Tb

Tb ≤ Tdb
Tdb = Tnb/γmb
Tnb = 0.90fubAn < fybAsb(γmb/γm0)

Tdb = 70.57 kN
SAFE
(d) Bolt subjected to combined shear and tension

(Vsb/Vdb)2+(Tb/Tdb)2 ≤ 1

where Vsb = factored shear force acting on bolt

Vdb = design shear capacity
Tb = factored tensile force acting on the bolt
Tdb = design tension capacity

Vsb = 12.375 kN (From STAAD)

Tb = 125 kN (From STAAD)

(Vsb/Vdb)2+(Tb/Tdb)2 = 0.104 < 1

SAFE
 Table 6.5 Stress and Deformation Characteristics for Normal Concrete
Strength Classes for Concrete
Strength Classes M-15 M-20 M-25 M-30 M-35 M-40 M-45
1 fck (Mpa) 15 20 25 30 35 40 45
2 fcm (Mpa) 25 30 35 40 45 50 55
3 fctm(Mpa) 1.6 1.9 2.2 2.5 2.8 3 3.3
4 fctk 0.05(Mpa) 1.1 1.3 1.5 1.7 1.9 2.1 2.3
5 fctk 0.95(Mpa) 2 2.5 2.9 3.2 1.9 2.1 2.3
6 Ecm(Gpa) 27 29 30 31 32 33 34
7 εc1 (per 1000) 1.8 1.9 2.0 2.0 2.1 2.2 2.3
8 εcu1 (per 1000) 3.5 3.5 3.5 3.5 3.5 3.5 3.5
9 εc2 (per 1000) 2.0 2.0 2.0 2.0 2.0 2.0 2.0
10 εcu2 (per 1000) 3.5 3.5 3.5 3.5 3.5 3.5 3.5

11 η 2.0 2.0 2.0 2.0 2.0 2.0 2.0

12 εc3 (per 1000) 1.8 1.8 1.8 1.8 1.8 1.8 1.8
13 εcu3 (per 1000) 3.5 3.5 3.5 3.5 3.5 3.5 3.5
rmal Concrete

M-50 M-55 M-60

50 55 60
60 65 70
3.5 3.7 4
2.5 2.6 2.8
2.5 2.6 2.8
35 36 37
2.3 2.4 2.4
3.5 3.5 3.5
2.0 2.0 2.0
3.5 3.5 3.5

2.0 2.0 2.0

1.8 1.8 1.8
3.5 3.5 3.5