# You are asked to perform structural analysis of a traffic and signal lighting pole and design: Mechanical Engineering Report, ICL, UK

 University Imperial College London (ICL) Subject Mechanical Engineering

Purpose: This project will help you to apply the theory to a practical structural design problem. You are given the opportunity to improve your understanding of theoretical and practical aspects of the theory taught in this course.

Project description: You are asked to perform structural analysis of a traffic and signal lighting pole and design it using the theory taught in this course. There is no unique design solution for this project, therefore you are highly encouraged to use your own understanding and approach.

There is also no restriction on the length of the project paper (preferably 3-5 pages). However, the following design and analysis steps are provided as a guidance. Please address all the requested

design aspects listed below. In each step, please list all your assumptions clearly and show your work and calculations accordingly.

(a) Please go outside and locate a traffic light pole that is designed to support at least 2-3 signal lights and sign plates on the nearest street in your neighborhood. Please capture a couple of images of the selected traffic light pole for illustration purposes in your paper. Fig. 1 depicts an example; however, you are supposed to use your own.

(b) Now, it is time to simply it and draw a free body diagram (FBD) to visualize the forces acting on the horizontal pole (mast arm) structure (Fig. 1 shows a sample FBD). Please approximate all the dimensions as close as possible to the real dimensions. You can simply consider the lights and sign plates as concentrated loads acting on the horizontal pole and its weight as the distributed force. In this step, assume there is no wind gust exerted by the structure.

(c) Using the FBD drawn in part-b and the beam deflection tables provided in your textbook, determine the cross-sectional geometry of the horizontal pole so that the maximum deflection of the horizonal pole does not exceed 100mm. (Hints: these poles typically have a hollow circular cross section, and you may assume that it has a uniform cross-section over the span. In addition, the horizontal pole can be assumed to be cantilevered to the vertical pole. You will also have to select a proper material in your design.)

(d) Now, estimate the pressure acting on the horizontal pole due to a side wind with a speed of 50 m/s and include it as a distributed force in your FBD. For this step you will have to figure out how to calculate the pressure force using a simplistic aerodynamic approach.

(e) With the updated FBD, it is time to calculate the combined stress-state at the critical crosssection of the horizontal pole. First, locate the critical cross-section in the horizontal pole and then figure out what is the critical stress-state at different points in that cross-section.

For the designed geometry and selected material, verify that the critical stress does not exceed the failure stress of the selected material. Also, please calculate the factor of safety. Your paper should be well structured in a typical scientific paper format. It must contain “introduction”, “theory”, “discussion”, and “references” sections. Please feel free to enrich your paper with high quality figures, schematics, graphs etc. if you think it is related to your design and analysis. Please make sure that you cite all the references you use in the paper and list them in the references section.