General Instructions. In problems requiring the specification of sizes for steel cable,...

General Instructions. In problems requiring the specification of sizes for steel cable, bar, or pipe, selections should be made from Tables 3.1–3.3. In all problems, write a brief technical report following the guidelines of Appendix A, where you summarize all pertinent information in a well-organized fashion. It should be written using proper, simple English that is easy for another engineer to read. Where appropriate, sketches, along with critical dimensions, should be included. Discuss the objectives and constraints considered in your design, the process used to arrive at your final design, safety issues if appropriate, and so on. The main discussion should be typed, and figures, if needed, can be computer-drawn or neatly hand-drawn. Include a neat copy of all supporting calculations in an appendix that you can refer to in the main discussion of your report. A length of a few pages, plus appendix, should be sufficient.

Design the cable support system for a radio tower of height 25 m. This includes specifying the radius R of the supports at points B, C, and D (as measured from the base of the tower) and the diameter of the steel cable. Remarks:

• All supports will be erected on a horizontal surface.

• Supports B, C, and D will each be located at the same radial distance R from the base of the tower (point O) such that

• The cables must be able to support a maximum horizontal storm force F = 18 kN from any direction in the horizontal plane.

• Neglect the weight of the cables in your calculations.

• Assume one of the cables is always slack and supports no load. For example, when force F lies in sector CAD (as shown), cable AB is slack.

In your report describe the merits of large versus small values of R and why you selected the value you did. State which orientation(s) of the storm force F lead to the most severe cable loads and how you determined these orientations.