Class Activity 2 - Truss_SkyCiv

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University Of Georgia *

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2110

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Mechanical Engineering

Date

Apr 3, 2024

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docx

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Uploaded by Adyjannu

Group Activity Workshop – 2D Truss Purpose 1. Practice to draw free-body diagram to describe 2D systems (CO #e) 2. Practice to solve 2D and 3D equilibrium systems (CO #f) 3. Practice to analyze simple trusses using method of joints and method of section (CO #g) 4. Practice to use appropriate mathematical, sketching, and modeling skills to describe concepts and systems (ABET #1) Tasks Please see the group that you have been assigned to on eLC. Discuss and solve following truss problems. Use sketches and diagrams to support your answers. Part A – Observe the symmetry! (10 points) A 2D truss system below has 5 elements and 4 joints. The truss system is roller supported at joint 1 and pin supported at joint 3. Calculate all member forces of the truss system using the method of joints ! Discuss your results! Assume a = 20 ft and P = 8 kips. Perform your calculations on a blank paper using the Given, Find, and Analyze layout. 2 @ a a 1 2 3 4 1 2 3 4 5 P x y Figure 1 Simple 2D truss structure (5 elements, 4 joints) Page 1 of 4

Part B – Build your analytical skills! (10 points) Some members are now added to the 2D truss system above to build a bridge structure as shown below. Note that the structure is symmetric about a line passing through nodes 3 and 7. Two-point loads P are applied to the bridge at joint 2 and 3. Calculate member forces 2, 3, 12 and 13 using the method of sections ! Discuss your results! Assume a = 20 ft and P = 8 kips. Perform your calculations on a blank paper using the Given, Find, and Analyze layout. 4 @ a a 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 9 10 11 12 13 x P P x y Figure 2 2D truss structure (13 elements, 8 joints) Page 2 of 4

Part C – Modeling: Simpler is better! (5 points) A simply supported truss bridge is shown in Figure 3.a. You are asked to:  Discuss the function of bracing (e.g. sway bracing, lateral bracing)!  Discuss the justifications to model the 3D truss bridge system into a 2D model (see Figure 3.b)!  Make comments on how you would distribute the gravitational loads (forces) applied at the top of the deck to the truss joints. Note that this is a good exercise to help you learn about LOAD PATH! This skill is important as you get into practical field. (a) 3D model 4 @ a a deck stringers bottom cord top cord 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 9 10 11 12 13 x y (b) 2D model Figure 3 Simply supported truss bridge Page 3 of 4

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Part D (BONUS) – Build your curiosity! Compare your results! (5 points) Finite element analysis is a computerized method for predicting how a system reacts to real-world forces, vibration, heat, fluid flow, magnetic, and other physical effects . This technique has been widely used in design industries of civil, aerospace, mechanical, and electrical engineering. The use of this analysis in engineering problems without proper understanding of engineering mechanics concepts, e.g., statics, dynamics, and strength of materials, etc, can deliver misleading results . Therefore, it is important to develop your engineering mechanics knowledge before using this software for the purpose of design and analysis. In this part, you will use a structural analysis software, called SkyCiv, based on finite element analysis to model and perform a simulation of the Truss structure on Part A of this group activity . At the end of this simulation, you will compare your group hand calculation results on the reaction forces and internal forces of the truss members and the results obtained from the SkyCiv software .  To have access to the SkyCiv software, please sign up for the FREE account ( https://skyciv.com/checkout/ ). You don’t need to install the software since the software is cloud- based. You only need a web browser (e.g., google chrome)  SkyCiv has recorded few tutorial videos to introduce you to the navigation and graphical user interface of this software: o https://youtu.be/taKSfuvwnCQ o https://youtu.be/EJZ_PcvMeqY  I also recorded the following videos to demonstrate how you could build a Truss structure in this software. These videos are recorded for my old classes. However, I think it is relevant to the Truss bridge model that you build on Part B. It is a 40+ minutes long video, but my past students have told me that it is clear and very easy to follow along. o https://tacomacc.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=1f2e27e9-3989-48b8- 8dcd-acb20177d2bd&start=undefined After modeling the truss bridge, run the simulation, and show the axial force values. You are asked to present a picture of these axial force values in the truss members produced by SkyCiv . Compare your result with your hand calculations on Part A. The picture will look something like the diagram you see in the last video above mins 33:19 Criteria Compiled all answers and solutions for PART A, B, C, and D into a folder. Label the folder as TeamNameClassActivityII . Zip the folder and submit the zipped folder on Canvas Please make sure to include your team members’ name in the solutions or answers. Your solutions will be graded based on the correctness of calculations (Part A and B) and modeling and correctness (Part D) and logical reasonings (Part C). Page 4 of 4