Design of Microwave Tower

DESIGN OF MICROWAVE TOWER SUBJECT NAME = DESIGN OF TALL STRUCTURES SUBJECT CODE = 2732005 PREPARED BY :CHIRAG MULCHANDANI (160410720007) ALIABBAS RETIWALA (160410720017) SAMIR PRAJAPATI (160410720015) ARJAV PATEL (160410720009) ( 160410720009)

GIVEN DATA :THE WIDTH AT THE TOP OF THE TOWER WEIGHT OF THE PLATFORM AT TOP WEIGHT OF RAILING AT TOP WEIGHT OF LADDER AND THE CAGE WEIGHT OF ANTENNA DISK AND FIXTURE SELF WEIGHT OF TRUSS LIVE LOAD WEIGHT OF MISCELLANEOUS ITEMS TERRAIN CATEGORY CLASS OF STRUCTURE HEIGHT OF TOWER

3.5 0.9 0.9 0.3 0.3 0.6 0.6 9 4.5 4.5 0.75 0.75 2.5 III B 55

m KN/m KN/m2 2 KN/m KN/m KN/m KN/m KN KN/m KN/m KN/m KN/m2 2 KN

m

SOLUTION :a) TRUSS CONFIGURATION :-

Base Width Top straight portion, Say Length of Leg member in this segment, Say Inclination of base leg cosθ cosθ

7 15 m 3m 0.04 (IN RADIAN) 0.9990443 1

Inclination Of diagonals Part-1

0.708626272 (IN RADIAN)

40.601303 (IN DEGREE)

Part-2

0 .8 5 1 4 0 0 2 3 6

4 8 .7 8 1 6 5

Part-3

0 .7 3 8 7 2 0 9 3 9

42.325601

2.505093 (IN DEGRE

part-4

0.788437668

45.17416

b)COMPUTATION OF FORCES AT BASE:GRAVITY LOADS

Weight from railing

4.2 kN

Weight of platform

11.025 kN

Live load on platform

9.1875 kN

Weight of ladder and cage

33 kN

Self weight of truss

247.5 kN

Miscellaneous items

2.5 kN

Total weight on 4 legs Weight of antenna on 2legs Force on each leg at base due to gravity loads

307.4125 kN 9 kN 81.35313 kN

EFFECT OF WIND LOAD

Basic wind speed K1 K2

K3

44 m/sec 1.07 0.88 1.01 1.06 1.098 1

for 10m for 25m for 40m for 55m

Design wind speed V10 V25 V40 V55 Design wind pressure

41.4304 47.5508 49.9048 51.69384

m/sec m/sec m/sec m/sec

P10 P25 P40 P55

1.029887 1.356647 1.494293 1.603352

Width of tower at 0m

KN/m2 KN/m2 KN/m2 KN/m2

b0

7m

at 10m b10

5.9 m

at 25m b25

4.7 m

at 40m b40

3.5 m

at 55m b55

3.5 m

Area of part 4 Area of part 3 Area of part 2 Area of part 1

64.5 79.5 61.5 52.5

m2 m2 m2 m2

Distance of C.g of parts from base

L.A 4 L.A 3 L.A 2 L.A 1

5.188679 17.86585 32.5 47.5

m m m m

Assume solidity ratio for parts 1,2,3 and 4 as 0.26,0.26,0.24 and 0.2 resp. Force coefficients(table 30 pg 47 IS 875 -part 3) Part 1 Part 2 Part 3 Part 4 Antenna disk

3 3 3.1 3.3 1.4

Consider wind blowing normal to one face LATERAL LOADS FOR:Part 1 65.65726 kN Part 2 71.68126 kN Part 3 80.24297 kN Part 4 39.85662 kN Antenna 15.86679 kN Total lateral load Say

273.3049 274 kN

Consider wind acting diagonally Moments of lateral loads at base : M1 3742.464 kN-m M2 2795.569 kN-m M3 1720.331 kN-m M4 248.1639 kN-m Ma 617.1667 kN-m Total Moment

9123.694 kN-m

Maximum force in one leg dye to WL

921.77148 kN

Maximum compressive force in leg Maximum uplift at base Maximum transverse shear at base

1003.1246 kN 840.41836 kN 274 kN

Loading at Members : For Panel 1

Vertical Members

Horizontal Members

Inclined Members

Load Considered

840.4183583 1003.124608

32.82862926

111.6186043

For Panel 2

840.4183583 1003.124608

35.84062811

100.8390258

For Panel 3

840.4183583 1003.124608

40.12148277

119.4729038

For Panel 4

840.4183583 1003.124608

19.92831009

85.44732671

Panel

Vertical Member

Horizontal Member

Inclined Member

Panel 1

ISA 200x200x25

ISA 65x65x6

ISA 90x90x8

Panel 2

ISA 200x200x25

ISA 65x65x6

ISA 90x90x10

Panel 3

ISA 200x200x25

ISA 65x65x10

ISA 90x90x12

Panel 4

ISA 200x200x25

ISA 80x80x6

ISA 90x90x12

Results :