# Calculating forces on a tilting tower

1. Sep 24, 2009

### djtexcarr

Please see attached excerpt of a report I have been studying.

I am going to be building a tilt up tower as in the diagram. However, I may be putting varying loads on the tower top, which they indicate to be 800#. On the second page of the pdf, it shows the tower section weights, lengths, etc and it shows the results of the calculations. Could someone please show me how they used the numbers they have to get the conclusions they derived? My goal is to create a spreadsheet in which I can "plug in" the variables and the resulting forces will automatically generate.

Thank you,

David

#### Attached Files:

• ###### 0614_001.pdf
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2. Sep 27, 2009

### CarlAK

Creating the shear & moment diagrams is first year structural engineering (end of the year) but not easy to explain, not briefly anyway. Not sure how the maximum force in a leg was determined, perhaps treating the max moment as a force "couple", divided between the legs.

3. Sep 27, 2009

### nvn

Let's call the two legs at the base of the tower point A, and the point where the cable is attached to the tower point B. It can be figured out that the angle of their cable at point B, measured from a horizontal line, is theta = 24.82 deg. By measuring an enlargement of their diagram, you could measure the angle of their gin pole, and measure the angle of their winch cable. Then, using geometry or trigonometry, you could compute the length of their gin pole. It can be seen in their loading diagram that the vertical reaction force at point A is 497 lbf. And the total load (lbf) for each uniformly-distributed load is written on each uniformly-distributed load, acting downward. As CarlAK mentioned, any statics or mechanics of materials text book will help you learn shear and moment diagrams. To derive the shear and moment diagrams, which you are asking about, they used statics, or static equilibrium of a simply-supported beam (with overhang).