Problem 2.4.1 STRUCTURAL design
Ryan Sauer Principles of Engineering 11/25/14 Worcester Tech/Stephen Decatur
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Research
To find how i wanted to build bridge I messed with the West Point Bridge Designer and saw how much each material cost. I saw how the price changes when you use solid or hollow members, but if you change material to cheaper or hollow the strength of the member decreases greatly. Also you could make the members thinner to make them cheaper and weaker, or thicker to cost more and be stronger.
Brainstorming other designs
I didnt use these designs because the costed too much or they were not strong enough.
Modifications
To modify my bridge i changed materials, made the members hollow or solid, changed the thickness, or moved the members around.
This bridge did not work, so i made the joints thicker depending on how much stress each joint was under.
This bridge worked but it was over budget so i had to make the joints hollow or make them smaller.
Test Report
Dennis H. Mahan Memorial Bridge
Project ID: 00001A-
Designed By: Ryan Sauer
# Material Type Cross Section Size (mm) Length (m) Compression Force Compression Strength Compression Status Tension Force Tension Strength Tension Status
1 CS Solid Bar 170x170 5.66 2223.46 3231.48 OK 0.00 6863.75 OK
2 CS Solid Bar 170x170 5.66 2182.47 3231.48 OK 0.00 6863.75 OK
3 CS Solid Bar 150x150 4.00 1543.24 3230.99 OK 0.00 5343.75 OK
4 CS Solid Bar 150x150 4.00 2772.19 3230.99 OK 0.00 5343.75 OK
5 CS Solid Bar 180x180 4.00 3725.47 5336.92 OK 0.00 7695.00 OK
6 CS Solid Bar 180x180 4.00 4368.75 5336.92 OK 0.00 7695.00 OK
7 CS Solid Bar 180x180 4.00 4692.92 5336.92 OK 0.00 7695.00 OK
8 CS Solid Bar 180x180 4.00 4396.68 5336.92 OK 0.00 7695.00 OK
9 CS Solid Bar 180x180 4.00 3772.02 5336.92 OK 0.00 7695.00 OK
10 CS Solid Bar 150x150 4.00 2830.16 3230.99 OK 0.00 5343.75 OK
11 CS Solid Bar 150x150 4.00 1572.22 3230.99 OK 0.00 5343.75 OK
12 CS Solid Bar 150x150 5.66 1846.32 2062.08 OK 0.00 5343.75 OK
13 CS Solid Bar 140x140 5.66 1466.64 1564.00 OK 0.00 4655.00 OK
14 CS Solid Bar 140x140 5.66 1085.38 1564.00 OK 0.00 4655.00 OK
15 CS Solid Bar 140x140 5.66 701.42 1564.00 OK 0.00 4655.00 OK
16 CS Hollow Tube 150x150x7 5.66 282.48 550.30 OK 323.47 950.95 OK
17 CS Solid Bar 140x140 5.66 660.43 1564.00 OK 0.00 4655.00 OK
18 CS Solid Bar 140x140 5.66 1044.38 1564.00 OK 0.00 4655.00 OK
19 CS Solid Bar 140x140 5.66 1425.65 1564.00 OK 0.00 4655.00 OK
20 CS Solid Bar 150x150 5.66 1805.33 2062.08 OK 0.00 5343.75 OK
21 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1526.71 5343.75 OK
22 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1257.45 5343.75 OK
23 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 987.85 5343.75 OK
24 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 716.36 5343.75 OK
25 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 444.86 5343.75 OK
26 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 617.70 5343.75 OK
27 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 745.34 5343.75 OK
28 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1016.84 5343.75 OK
29 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1286.43 5343.75 OK
30 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1555.70 5343.75 OK
31 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1572.22 5343.75 OK
32 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 2830.16 5343.75 OK
33 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 3772.02 5343.75 OK
34 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4396.68 5343.75 OK
35 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4702.23 5343.75 OK
36 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4702.23 5343.75 OK
37 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4692.92 5343.75 OK
38 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4368.75 5343.75 OK
39 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 3725.47 5343.75 OK
40 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 2772.19 5343.75 OK
41 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1543.24 5343.75 OK
Project ID: 00001A-
Designed By: Ryan Sauer
# Material Type Cross Section Size (mm) Length (m) Compression Force Compression Strength Compression Status Tension Force Tension Strength Tension Status
1 CS Solid Bar 170x170 5.66 2223.46 3231.48 OK 0.00 6863.75 OK
2 CS Solid Bar 170x170 5.66 2182.47 3231.48 OK 0.00 6863.75 OK
3 CS Solid Bar 150x150 4.00 1543.24 3230.99 OK 0.00 5343.75 OK
4 CS Solid Bar 150x150 4.00 2772.19 3230.99 OK 0.00 5343.75 OK
5 CS Solid Bar 180x180 4.00 3725.47 5336.92 OK 0.00 7695.00 OK
6 CS Solid Bar 180x180 4.00 4368.75 5336.92 OK 0.00 7695.00 OK
7 CS Solid Bar 180x180 4.00 4692.92 5336.92 OK 0.00 7695.00 OK
8 CS Solid Bar 180x180 4.00 4396.68 5336.92 OK 0.00 7695.00 OK
9 CS Solid Bar 180x180 4.00 3772.02 5336.92 OK 0.00 7695.00 OK
10 CS Solid Bar 150x150 4.00 2830.16 3230.99 OK 0.00 5343.75 OK
11 CS Solid Bar 150x150 4.00 1572.22 3230.99 OK 0.00 5343.75 OK
12 CS Solid Bar 150x150 5.66 1846.32 2062.08 OK 0.00 5343.75 OK
13 CS Solid Bar 140x140 5.66 1466.64 1564.00 OK 0.00 4655.00 OK
14 CS Solid Bar 140x140 5.66 1085.38 1564.00 OK 0.00 4655.00 OK
15 CS Solid Bar 140x140 5.66 701.42 1564.00 OK 0.00 4655.00 OK
16 CS Hollow Tube 150x150x7 5.66 282.48 550.30 OK 323.47 950.95 OK
17 CS Solid Bar 140x140 5.66 660.43 1564.00 OK 0.00 4655.00 OK
18 CS Solid Bar 140x140 5.66 1044.38 1564.00 OK 0.00 4655.00 OK
19 CS Solid Bar 140x140 5.66 1425.65 1564.00 OK 0.00 4655.00 OK
20 CS Solid Bar 150x150 5.66 1805.33 2062.08 OK 0.00 5343.75 OK
21 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1526.71 5343.75 OK
22 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1257.45 5343.75 OK
23 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 987.85 5343.75 OK
24 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 716.36 5343.75 OK
25 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 444.86 5343.75 OK
26 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 617.70 5343.75 OK
27 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 745.34 5343.75 OK
28 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1016.84 5343.75 OK
29 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1286.43 5343.75 OK
30 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1555.70 5343.75 OK
31 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1572.22 5343.75 OK
32 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 2830.16 5343.75 OK
33 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 3772.02 5343.75 OK
34 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4396.68 5343.75 OK
35 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4702.23 5343.75 OK
36 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4702.23 5343.75 OK
37 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4692.92 5343.75 OK
38 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 4368.75 5343.75 OK
39 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 3725.47 5343.75 OK
40 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 2772.19 5343.75 OK
41 CS Solid Bar 150x150 4.00 0.00 3230.99 OK 1543.24 5343.75 OK
Cost Calculation Report
Dennis H. Mahan Memorial Bridge
Project ID: 00001A-
Iteration #25 (Mon, 1 Dec 2014, 10:01:18)
Type of Cost Item Cost Calculation Cost
Material Cost (M) Carbon Steel Solid Bar (32536.4 kg) x ($4.50 per kg) x (2 Trusses) = $292,828.05
Carbon Steel Hollow Tube (177.8 kg) x ($6.30 per kg) x (2 Trusses) = $2,240.32
Connection Cost (C) (22 Joints) x (500.0 per joint) x (2 Trusses) = $22,000.00
Product Cost (P) 6 - 140x140 mm Carbon Steel Bar (%s per Product) = $1,000.00
27 - 150x150 mm Carbon Steel Bar (%s per Product) = $1,000.00
1 - 150x150x7 mm Carbon Steel Tube (%s per Product) = $1,000.00
2 - 170x170 mm Carbon Steel Bar (%s per Product) = $1,000.00
5 - 180x180 mm Carbon Steel Bar (%s per Product) = $1,000.00
Site Cost (S) Deck Cost (11 4-meter panels) x ($5,150.00 per panel) = $56,650.00
Excavation Cost (0 cubic meters) x ($1.00 per cubic meter) = $0.00
Abutment Cost (2 standard abutments) x ($7,000.00 per abutment) = $14,000.00
Pier Cost No pier = $0.00
Cable Anchorage Cost No anchorages = $0.00
Total Cost M + C + P + S $295,068.36 + $22,000.00 + $5,000.00 + $70,650.00 = $392,718.36
Project ID: 00001A-
Iteration #25 (Mon, 1 Dec 2014, 10:01:18)
Type of Cost Item Cost Calculation Cost
Material Cost (M) Carbon Steel Solid Bar (32536.4 kg) x ($4.50 per kg) x (2 Trusses) = $292,828.05
Carbon Steel Hollow Tube (177.8 kg) x ($6.30 per kg) x (2 Trusses) = $2,240.32
Connection Cost (C) (22 Joints) x (500.0 per joint) x (2 Trusses) = $22,000.00
Product Cost (P) 6 - 140x140 mm Carbon Steel Bar (%s per Product) = $1,000.00
27 - 150x150 mm Carbon Steel Bar (%s per Product) = $1,000.00
1 - 150x150x7 mm Carbon Steel Tube (%s per Product) = $1,000.00
2 - 170x170 mm Carbon Steel Bar (%s per Product) = $1,000.00
5 - 180x180 mm Carbon Steel Bar (%s per Product) = $1,000.00
Site Cost (S) Deck Cost (11 4-meter panels) x ($5,150.00 per panel) = $56,650.00
Excavation Cost (0 cubic meters) x ($1.00 per cubic meter) = $0.00
Abutment Cost (2 standard abutments) x ($7,000.00 per abutment) = $14,000.00
Pier Cost No pier = $0.00
Cable Anchorage Cost No anchorages = $0.00
Total Cost M + C + P + S $295,068.36 + $22,000.00 + $5,000.00 + $70,650.00 = $392,718.36
Final design justification
![Picture](/uploads/2/3/4/1/23417088/2752621_orig.png)
The reason I used carbon steel was because it was cheap but still strong. I designed the bridge with squares with a diagonal member going through the middle because I think that is stronger then using triangles. I also slanted the member in the middle differently depending on where it was. I made it slant up towards the middle of the bridge.
References
As a reference I looked at the pre-made templates to see how well each bridge worked then I made my design based on the bridge that I thought worked best.
Conclusion
1. Depending on the amount of stress applied you can change the material weaker for a smaller force to save money or change the material to a stronger one if a stronger force is applied.
2. Compression and tension can work together to make the bridge stronger because you can add members that are in tension to lessen a compression force.
2. Compression and tension can work together to make the bridge stronger because you can add members that are in tension to lessen a compression force.