I would like your best handwriting to understand A television company wishes to
ID: 1767465 • Letter: I
Question
I would like your best handwriting to understand
A television company wishes to erect a reception tower with a total height of 170 m. This is to be done as shown in Fig. (rigidly fixed at ground) signal reception disc 30° 5 kN 20 m If the total weight of the tower is 200 kN (which can be taken as acting at mid-height), and there are horizontal wind forces acting at B and C, of 40 kN and 5 kN respectively, both with a direction making a 30° angle to the positive x-direction as shown. 30° 40 kN 150 m mast Find the reactions at the base of the mast. (see free-body diagram on next slide)Explanation / Answer
This problem is purely two dimensional and it is only restrained at bottom. So there are Rx, Rz and My are reactions
Equilibrium of x-direction gives 5cos(30)+40cos(30)+Rx = 0
Rx = -38.97 kN
Equilibrium of y-direction gives 5sin(30)+40sin(30)-200+Ry = 0
Ry = 177.5 kN
Equilibrium of rotation about y axis gives
-5cos(30)*170-40cos(30)*150+My = 0
My = 5932.27 kNm (anticlockwise)