Reference no: EM132860523
CEE 3404 Theory of Structures
Class Project
Overview:
Your team has finalized the strength-based design of the truss bridge shown below in Figure 1. It was found that the controlling strength-based criteria for failure was 396.7 lbs at a joint location of J2. However, this loading is only half of the bridge's available capacity (due to the fact we are only analyzing one side of the truss). The NASA crew did the final weigh-in for the total weight of the transport crawler and new space ship, which weighs 400 lbs (this loading is for the entire truss structure).
While this bridge has sufficient strength capacity (based on our calculations) to let, the transport crawler cross the bridge with no problems, the crew at NASA is concerned with deflections in the structure. The owner of Spaze Z (Zlon Smell) wants to have a final watch party to see the new spaceship cross the bridge as a celebration of its final send-off before it goes into space.
NASA being extremely reputable, dosent want the newly designed bridge to sag for this glorious send-off like this incident. Your boss wants you to calculate different deflections on the bridge and ensure that these deflections will not exceed the perceivable vertical deflection limit.
Deliverables:
Remember, we want to turn in a professional technical document to a client here. See the project one & 2 deliverable solutions as a template, or feel free to look at other technical submittals online. Whatever you submit should be neat and professional.
*Remember there are 2 sides to our truss structure, so redistribute load accordingly in your calculations.
1) The client would like to know what the factor of safety for this bridge is (Ultimate stress of the material / the largest stress being placed on the structure from the loading of the transport crawler). You should know the controlling loading from deliverable 2 (the location you will need to resolve for the stresses). Please show any hand cals and a snip from Mastan 2 of this loading.
2) Your boss is confident in Mastans 2's abilities to complete structural analysis; however, she still wants you to verify that the program is working correctly via hand. She has given you the real and virtual loading diagrams in Figure 2 a and b, respectively, to solve for the real deflections at joint 2.
a. Real Loading
b. Virtual Loading
In completing the deflection at joint 2 please fill out Table 1. Hint -- the axial loads for these loading cases are going to be linear. Please provide the equation used to solve for this deflection and any supplemental hand calcs required in the solving of this problem.
3) Calculate the deflection at joint 2 due to the real loading using Mastan 2. Compare the deflections from part 2 (hand calcs) to that of deflections solved using Mastan 2. Are these deflections at joint 2 the same based on the hand clacs and Mastan 2 ? If they are not, what do you think caused this difference? Please provide a snip from Mastan 2 of the deflected shape for this loading case.
4) The NASA Transport Crawler is referred to as a moving load, meaning that the load will translate across the driving surface of the structure. The length of the transport crawler is
13.5 in. A profile view of the NASA replacement bridge and transport crawler loading can be seen in Figure 3.
Your boss has simplified this moving loading into the 4 cases shown in Figure 4 a-d. Please run these different loading scenarios in Mastan 2. Determine which loading scenario returns the highest deflection and at what joint this occurs, in doing this, please complete Table 2. Please denote the loading, joint location, and max deflection, also provide a snip of the entire trusses deflected shape for the controlling deflection loading. Are you surprised about the deflected shape based on the loadings? How did the controlling strength limit state loading location vary from the controlling deflection limit state? What was the max axial load in the controlling deflection limit state compared to the axial capacity of a member (491 lbs)? Overall how do strength and deflection limit states give insight into the design process?
5) NASA wants to use a vertical deflection criteria of L/200. L= the length of the bridge span (53.74 in). Which results in an allowable deflection limit of 0.27 in. Based on the current design of the bridge, will this bridge meet this criteria? If the bridge does not meet this requirement and we wanted to meet the 0.27 in deflection limit, what cross-sectional area of the members would meet this requirement (assuming we replace all the members)? Show a Mastan 2 snip of the deflected shape of the controlling loading's deflected shape, meeting this deflection requirement. What are 3 ways that the deflection of the bridge could be reduced? What are the pros and cons of each method? Which would you implement on a bridge like ours?
Attachment:- Theory of Structures.rar