Oct 28, 2016 Kevin R. Kline, PE, District Executive PennDOT Engineering District 2-0 1924 Daisy Street - P.O. Box 342 Clearfield County, PA 16830 Dear Mr. Kline: Reference. PennDOT Engineering District 2-0, Statement of Work, subj: Concept Design for Vehicle Bridge over Spring Creek along Puddintown Road in College Township, Centre County, PA, dated September 2, 2016. Statement of Problem. A bridge located over Spring Creek along Puddintown Road in College Township, Center County, PA was destroyed due to flooding in the local area. The bridge is located on a road that expects heavy traffic and provides vital vehicle access to the Mount Nittany Medical Center. Traffic has been disrupted, commerce has been affected and the residents of State College are at risk. Objective. Pennsylvania Department of Transportation of (PennDOT) Engineering District 2-0 must design a vehicle bridge over Spring Creek along Puddintown Road in College Township, Center County, PA under $250,000 that replaces the previous bridge that was destroyed due to local flooding. Design Criteria. PennDOT District 2-0 has established that both a Warren through truss bridge and a Howe through truss bridge shall be analyzed. The bridge to be built is to include: standard abutments, no piers (one span), deck material shall be medium strength concrete (0.23 meters thick), no cable anchorages and designed for the load of two AASHTO H20-44 trucks (225kN) with one in each traffic lane. The bridge deck and the deck span are to be 20 meters and 40 meters respectively. 1 | Page Fall 2016 School of Engineering Design, Technology and Professional Programs 213 Hammond Building University Park, PA 16802-2701
Transcript
Oct 28, 2016
Kevin R. Kline, PE, District ExecutivePennDOT Engineering District 2-01924 Daisy Street - P.O. Box 342Clearfield County, PA 16830
Dear Mr. Kline:
Reference. PennDOT Engineering District 2-0, Statement of Work, subj: Concept Design for Vehicle Bridge over Spring Creek along Puddintown Road in College Township, Centre County, PA, dated September 2, 2016.
Statement of Problem. A bridge located over Spring Creek along Puddintown Road in College Township, Center County, PA was destroyed due to flooding in the local area. The bridge is located on a road that expects heavy traffic and provides vital vehicle access to the Mount Nittany Medical Center. Traffic has been disrupted, commerce has been affected and the residents of State College are at risk.
Objective. Pennsylvania Department of Transportation of (PennDOT) Engineering District 2-0 must design a vehicle bridge over Spring Creek along Puddintown Road in College Township, Center County, PA under $250,000 that replaces the previous bridge that was destroyed due to local flooding.
Design Criteria. PennDOT District 2-0 has established that both a Warren through truss bridge and a Howe through truss bridge shall be analyzed. The bridge to be built is to include: standard abutments, no piers (one span), deck material shall be medium strength concrete (0.23 meters thick), no cable anchorages and designed for the load of two AASHTO H20-44 trucks (225kN) with one in each traffic lane. The bridge deck and the deck span are to be 20 meters and 40 meters respectively.All other design criteria (including the steel member type, steel cross section type, and steel member size) were left to the design team, thus allowing room for improvisation on the design.
Technical Approach.
Phase 1: Economic Efficiency. The bridge design software used during the experimental design phase allowed us to build a bridge that worked, and start shaving down on the quality of materials until it was under budget, yet still structurally sound.
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School of Engineering Design, Technology and Professional Programs
213 Hammond BuildingUniversity Park, PA 16802-2701
Phase 2: Structural Efficiency. We experimented a lot with not only the type of the material, but also the length of the material. Through experimentation, we found that if the top chords angled upwards towards the center of the bridge, the structure increased in stability and we were, thus, able to use cheaper materials to save money.
Results.
Phase 1: Economic Efficiency. We held constant the amount of popsicle sticks we could use. This simulated a real-life situation in which we had a budget of money, and were only allowed to allocate a set budget towards materials
Phase 2: Structural Efficiency. It was determined that much of the integrity of the structure would be decided in the joints, as the glue we were using seemed to act weaker that we had hoped. We centered the design around the principle of interlocking popsicles at the joints. This gave us twice the surface area to glue on, and therefore twice the strength of the bonds. We succeeded in doing so on the Warren Truss bridge, as critical failure occurred halfway down one of the beams on the bottom chord.
Best Solution.
In terms of economic efficiency, the Warren truss bridge barely trumped the Howe truss bridge. The Warren truss bridge's cost, at $248,799, was calculated to be $249 cheaper than the Howe truss bridge, estimated to cost $249,048. While the bridges cost essentially the same to make, it should be noted that the Warren bridge technically was more economically efficient. In terms of structural efficiency, the Warren truss bridge, again, trumped the Howe truss bridge. Values of the Geometric mean, mean, minimum, maximum, and range were substantially higher in all categories in favor of the Warren truss bridge.
In terms of Design efficiency, the Warren truss bridge, once again, is clearly a more viable option. The Howe truss bridge had a design efficiency coefficient of 1,423, whereas the Warren truss bridge had a structural efficiency coefficient of 679. This means that the cost per structural efficiency unit was much lower for the Warren truss bridge.
The total connection cost was higher for the Warren truss bridge ($800 higher), but it should be noted that the additional cost is nearly negligible, as it accounts for only 5% of the total connection cost. In simple terms, the Warren truss bridge's connection costs run only 5% more. The product cost for the Warren truss bridge was lower than the cost for the Howe bridge. The material cost, however, was slightly higher for the Warren Truss bridge than it was for the Howe truss bridge. The difference, however, can be negligible (as was the case for the connection cost). This is because the material cost only runs 0.7% more expensive for the Warren bridge, as opposed to the Howe truss bridge.
With all of these factors taken into account, the Warren bridge is clearly the better option.
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Conclusions and Recommendations. The through truss bridge that we would strongly recommend that you use is the Warren Truss Bridge. This bridge will be the most resistive bridge type when it comes to flooding, most cost efficient, and can hold the highest load. The next step that we should take to advance our project is hiring a construction team, and get this bridge in place immediately due to its essential use in the community.
Respectfully,
Varshini ChellapillaEngineering StudentEDSGN100 Section 001Design Team 2CARV EngineersCollege of EngineeringPenn State University
Cameron WilsonEngineering StudentEDSGN100 Section 001Design Team 2CARV EngineersCollege of EngineeringPenn State University
Alexis PritchardEngineering StudentEDSGN100 Section 001Design Team 2CARV EngineersCollege of EngineeringPenn State University
Rafael SaavedraEngineering StudentEDSGN100 Section 001Design Team 2CARV EngineersCollege of EngineeringPenn State University
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ATTACHMENT 1Phase 1: Economic Efficiency
Howe Truss. The Howe Truss Bridge was built by engineers Varshini Chellapilla and by Rafael Saavedra. Both members were able to build this bridge within the budget established: 250,000$. The final price was $249,038. Even though it is barely within the budget established, the engineers met the goal. Materials such as carbon steel and quenched steel were used to make. 25 tubes of carbon steel were used. Each of the cost 1,000$. At a first glance, it might seem the engineers could have used less expensive materials, but after their research and analysis, they determined that one the materials that adjusted to the budget and to the physical circumstances was carbon steel. The other material used was quenched tempered steel. In this case, 13 quenched tempered tubes were used. Each tube had a cost of a 1,000$. The quenched tempered was within our budget and met the physical objectives established. The cost of 10 deck panels was 47,000$, the excavation cost for 19,400 cubic meters was 19,400$, and the abutment cost, of two standard abutments, was 11,000$. There were also connection costs of 20 joints used in the Howe Truss Bridge. The total connection cost was 16,000$. As said before, the final cost for this Howe Truss bridge was within the budget. It cost 249,038$. The tabulated cost calculation report is in Table 1, the tabulated load test report is in Table 2, and the tabulated member detail report is in Table 3.
Warren Truss. The Warren Truss bridge was built by engineers Cameron Wilson and Alexis Pritchard. They both managed to build this bridge within the established budget of $250,000. Both engineers built this bridge with an outstanding economic efficiency, with a final cost of 248,799$. In this Warren Truss Bridge, only carbon steel was used. 35 carbon steel tubes before. As said in the Howe Truss Bridge case, carbon steel is a great material to use because its final cost is within the budget. So it is relatively a less expensive material than the other options available in the market. The connection cost was 16,800$. 21 connection joints were used in this Warren Truss Bridge. The cost of 10 deck panels was 47,000$, the excavation cost for 19,400 cubic meters was 19,400$, and the abutment cost, of two standard abutments, was 11,000$. In summary, engineers Cameron Wilson and Alexis Pritchard both managed to meet the economic and physical goals in the building of this bridge. As established before, the final price was within the budget with a cost of 248,799$. The tabulated cost calculation report is in Table 4, the tabulated load test report is in Table 5, and the tabulated member detail report is in Table 6.
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ATTACHMENT 2Phase 2: Structural Efficiency
Howe Truss. This prototype of the Howe truss bridge was built by engineers Cameron Wilson and Rafael Saavedra. This bridge took the engineers about three complete working days to create. They managed themselves to used only popsicle sticks and glue. The engineers had one of the structural efficiencies in the class with 175 as shown in TABLE 8.
Prototype Bridge. The engineers managed to use only materials such as glue and popsicle sticks. The upper cord was built with 2 popsicles sticks in each side. The lower cord, that had the responsibility of holding the decks, was built with
Load Testing. Our Howe Truss Bridge did not do as nearly well as we anticipated. The bridge weighed 83.7 grams and could only hold 32.4lbs. This was average compared to everyone else's bridge. These bridges could not hold nearly as much as the Warren Bridges. The structural efficiency is in the median of all the other bridges.
Forensic Analysis. The Howe truss bridge's failure was largely due to a weakly glued joint. This was determined because there was no fracturing of an individual member, only a clean separation of the bottom chord.
Results. An Excel bar chart has been provided below under Figures (see FIGURE 3). This chart compares the structural efficiencies of each Howe bridge built by the EDSGN100 Design Teams. The structural efficiency of our Howe bridge has been calculated to 175.
Warren Truss. This prototype for the Warren Truss was excellently executed. The engineers built this in three days in class and only used glue and popsicle sticks to build it. The structural efficiency is 366.
Prototype Bridge. The method we used to build the bridge was, we first drew the bridge out and planned where each popsicle stick would go. We used the design we designed in the software. The materials we used in designing the bridge were popsicle sticks and glue. We use a total of thirty popsicle sticks. Our Bridge was approximately a foot long and three inches wide.
Load Testing. When tested, the Warren Trust Bridge failed at 63.3lbs. This was much higher than a lot of other bridges in the class and over shot our estimates. The bridge weighed a total of 78.6 grams. Thus, the overall structural efficiency for our bridge was 366. Compared to the other bridges in the class, our bridge did quite well. We were above a lot of the other bridges, but not one of the highest ones ranked. The load testing results for the Warren Truss Bridge are in TABLE 7.
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Forensic Analysis. A member on the bottom part snapped. The stress and pressure was too strong for the popsicle stick, and therefore it broke. In the next design, the pressure will be more equally distributed so more weight can be held.
Results. An Excel bar chart has been provided below under Figures (see FIGURE 4). This chart compares the structural efficiency is each Warren bridge built by the EDSGN100 Design Teams. The structural efficiency of our Warren bridge has been calculated to 366.
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TABLES
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Table 1Cost Calculation Report from Bridge Designer 2016 for the Howe Truss Bridge
Type of Cost Item Cost Calculation Cost
Material Cost (M) Carbon Steel Hollow Tube
7091.2 kg) x ($6.30 per kg) x (2 Trusses)
$89,348.81
Quenched & Tempered Steel Hollow Tube
(3395.4 kg) x ($7.70 per kg) x (2 Trusses)
$52,289.54
Connection Cost (C) (20 Joints) x (400.0 per joint) x (2
Trusses)
$16,000.00
Product Cost (P) 2 - 120x120x6 mm Carbon Steel Tube
(%s per Product) $1,000.00
2 - 130x130x6 mm Quenched & Tempered
Steel Tube
(%s per Product) $1,000.00
4 - 140x140x7 mm Carbon Steel Tube
(%s per Product) $1,000.00
1 - 140x140x7 mm Quenched & Tempered
Steel Tube
(%s per Product) $1,000.00
2 - 160x160x8 mm Carbon Steel Tube
(%s per Product) $1,000.00
2 - 170x170x8 mm Carbon Steel Tube
(%s per Product) $1,000.00
2 - 190x190x9 mm Quenched & Tempered
Steel Tube
(%s per Product) $1,000.00
4 - 200x200x10 mm Quenched & Tempered
Steel Tube
(%s per Product) $1,000.00
8 - 220x220x11 mm Carbon Steel Tube
(%s per Product) $1,000.00
2 - 220x220x11 mm Quenched & Tempered
Steel Tube
(%s per Product) $1,000.00
3 - 240x240x12 mm Carbon Steel Tube
(%s per Product) $1,000.00
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1 - 260x260x13 mm Carbon Steel Tube
(%s per Product) $1,000.00
2 - 300x300x15 mm Carbon Steel Tube
(%s per Product) $1,000.00
Site Cost (S) Deck Cost (10 4-meter panels) x ($4,700.00 per panel)
$47,000.00
Excavation Cost (19,400 cubic meters) x ($1.00 per cubic
meter)
$19,400.00
Abutment Cost (2 standard abutments) x
($5,500.00 per abutment)
$11,000.00
Pier Cost No pier $0.00
Cable Anchorage Cost No anchorages $0.00
Total Cost M + C+ P + S $141,638.35 + $16,000.00 + $14,000.00 + $77,400.00
$249,038.35
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# Material
Type
Cross Secti
on
Size
(mm)
Length
(m)
Compression Force
Compression
Strength
Compression
Status
Tension
Force
Tension
Strength
Tension
Status
1 CS Tube 220 5.10 0.80 0.80 OK 0.00 0.00 OK
2 CS Tube 260 4.12 0.78 0.78 OK 0.00 0.00 OK
3 CS Tube 240 4.12 0.90 0.90 OK 0.00 0.00 OK
4 CS Tube 220 3.16 0.82 0.82 OK 0.00 0.00 OK
5 QTS Tube 200 4.12 0.91 0.91 OK 0.00 0.00 OK
6 QTS Tube 200 4.00 0.84 0.84 OK 0.00 0.00 OK
7 QTS Tube 200 4.00 0.84 0.84 OK 0.00 0.00 OK
8 QTS Tube 200 4.12 0.89 0.89 OK 0.00 0.00 OK
9 CS Tube 140 5.00 0.00 0.00 OK 0.72 0.72 OK
10
CS Tube 140 7.00 0.00 0.00 OK 0.69 0.69 OK
11
CS Tube 140 7.00 0.00 0.00 OK 0.66 0.66 OK
12
CS Tube 140 5.00 0.00 0.00 OK 0.70 0.70 OK
13
CS Tube 300 4.00 0.00 0.00 OK 0.55 0.55 OK
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Table 2Load Test Results Report from Bridge Designer 2015 for the Howe Truss Bridge
14
CS Tube 300 4.00 0.00 0.00 OK 0.55 0.55 OK
15
QTS Tube 220 5.00 0.62 0.62 OK 0.00 0.00 OK
16
QTS Tube 220 6.40 0.97 0.97 OK 0.00 0.00 OK
17
QTS Tube 130 4.12 0.00 0.00 OK 0.85 0.85 OK
18
QTS Tube 130 4.12 0.00 0.00 OK 0.65 0.65 OK
19
CS Tube 220 4.00 0.00 0.00 OK 0.92 0.92 OK
20
CS Tube 220 4.00 0.00 0.00 OK 0.98 0.98 OK
21
CS Tube 220 4.00 0.00 0.00 OK 0.97 0.97 OK
22
CS Tube 220 4.00 0.00 0.00 OK 0.89 0.89 OK
23
CS Tube 240 4.00 0.00 0.00 OK 0.84 0.84 OK
24
CS Tube 240 4.00 0.00 0.00 OK 0.83 0.83 OK
25
QTS Tube 140 7.00 0.00 0.00 OK 0.36 0.36 OK
26
CS Tube 170 8.06 0.77 0.77 OK 0.06 0.06 OK
27
CS Tube 170 8.06 0.70 0.70 OK 0.09 0.09 OK
28
QTS Tube 190 6.40 0.86 0.86 OK 0.00 0.00 OK
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29
QTS Tube 190 6.40 0.61 0.61 OK 0.00 0.00 OK
30
CS Tube 160 8.06 0.26 0.26 OK 0.30 0.30 OK
31
CS Tube 160 8.06 0.22 0.22 OK 0.37 0.37 OK
32
CS Tube 120 6.00 0.00 0.00 OK 0.51 0.51 OK
33
CS Tube 120 6.00 0.20 0.20 OK 0.48 0.48 OK
34
QTS Tube 160 7.21 0.86 0.86 OK 0.00 0.00 OK
35
QTS Tube 160 7.21 0.82 0.82 OK 0.03 0.03 OK
36
CS Tube 220 4.00 0.00 0.00 OK 0.48 0.48 OK
37
CS Tube 220 4.00 0.00 0.00 OK 0.79 0.79 OK
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Table 3 Member Details Report from Bridge Designer 2016 for the Howe Truss Bridge Member with the
Highest Compression (or Tension) Force/Strength Ratio
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Table 4Cost Calculation Report from Bridge Designer 2016 for the Warren Truss Bridge
Type of Cost Item Cost Calculation Cost
Material Cost (M) Carbon Steel Hollow Tube
(11476.1 kg) x ($6.30 per kg) x (2 Trusses)
$144,599.36
Connection Cost (C) (21 Joints) x (400.0 per joint) x (2
Trusses)
$16,800.00
Product Cost (P) 4 - 110x110x5 mm Carbon Steel Tube
(%s per Product) $1,000.00
4 - 130x130x6 mm Carbon Steel Tube
(%s per Product) $1,000.00
6 - 140x140x7 mm Carbon Steel Tube
(%s per Product) $1,000.00
4 - 180x180x9 mm Carbon Steel Tube
(%s per Product) $1,000.00
4 - 220x220x11 mm Carbon Steel Tube
(%s per Product) $1,000.00
4 - 240x240x12 mm Carbon Steel Tube
(%s per Product) $1,000.00
6 - 260x260x13 mm Carbon Steel Tube
(%s per Product) $1,000.00
2 - 280x280x14 mm Carbon Steel Tube
(%s per Product) $1,000.00
2 - 300x300x15 mm Carbon Steel Tube
(%s per Product) $1,000.00
3 - 320x320x16 mm Carbon Steel Tube
(%s per Product) $1,000.00
Site Cost (S) Deck Cost (10 4-meter panels) x ($4,700.00 per panel)
$47,000.00
Excavation Cost (19,400 cubic meters) x ($1.00 per cubic
meter
$19,400.00
Abutment Cost (2 standard abutments) x
($5,500.00 per abutment)
$11,000.00
Pier Cost No Pier $0.00
Cable Anchorage Cost No Anchorage $0.00
Total Cost M + C+ P + S $144,599.36 + $16,800.00 + $10,000.00 + $77,400.00
$248,799.36
# Material
Type
Cross Secti
on
Size
(m
Length
(m)
Compression Force
Compression
Strength
Compression
Status
Tension
Statu
Tension
Stren
Tension
Force
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Table 5Load Test Results Report from Bridge Designer 2015 for the Warren Truss Bridge
m) s gth 1 CS Tube 240 4.12 0.75 0.75 OK OK 0.00 0.00
2 CS Tube 260 4.12 0.87 0.87 OK OK 0.00 0.00
3 CS Tube 280 4.12 0.79 0.79 OK OK 0.00 0.00
4 CS Tube 320 4.00 0.60 0.60 OK OK 0.00 0.00
5 CS Tube 320 4.00 0.63 0.63 OK OK 0.00 0.00
6 CS Tube 320 4.00 0.60 0.60 OK OK 0.00 0.00
7 CS Tube 280 4.12 0.78 0.78 OK OK 0.00 0.00
8 CS Tube 260 4.12 0.85 0.85 OK OK 0.00 0.00
9 CS Tube 240 4.12 0.73 0.73 OK OK 0.00 0.00
10
CS Tube 240 3.61 0.75 0.75 OK OK 0.00 0.00
11
CS Tube 220 3.61 0.00 0.00 OK OK 0.55 0.55
12
CS Tube 180 4.47 0.77 0.77 OK OK 0.00 0.00
13
CS Tube 140 4.47 0.10 0.10 OK OK 0.74 0.74
14
CS Tube 140 5.39 0.41 0.41 OK OK 0.04 0.04
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15
CS Tube 130 5.39 0.00 0.00 OK OK 0.43 0.43
16
CS Tube 110 6.32 0.93 0.93 OK OK 0.72 0.72
17
CS Tube 130 6.32 0.46 0.46 OK OK 0.92 0.92
18
CS Tube 140 6.32 0.68 0.68 OK OK 0.07 0.07
19
CS Tube 110 6.32 0.85 0.85 OK OK 0.75 0.75
20
CS Tube 110 6.32 0.00 0.00 OK OK 0.68 0.68
21
CS Tube 140 6.32 0.31 0.31 OK OK 0.10 0.10
22
CS Tube 140 6.32 0.27 0.27 OK OK 0.70 0.70
23
CS Tube 110 6.32 0.99 0.99 OK OK 0.87 0.87
24
CS Tube 130 5.39 0.27 0.27 OK OK 0.41 0.41
25
CS Tube 130 5.39 0.99 0.99 OK OK 0.16 0.16
26
CS Tube 140 4.47 0.00 0.00 OK OK 0.72 0.72
27
CS Tube 180 4.47 0.74 0.74 OK OK 0.00 0.00
28
CS Tube 220 3.61 0.00 0.00 OK OK 0.54 0.54
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29
CS Tube 240 3.61 0.73 0.73 OK OK 0.00 0.00
30
CS Tube 180 4.00 0.00 0.00 OK OK 0.64 0.64
31
CS Tube 220 4.00 0.00 0.00 OK OK 0.89 0.89
32
CS Tube 260 4.00 0.00 0.00 OK OK 0.75 0.75
33
CS Tube 260 4.00 0.00 0.00 OK OK 0.75 0.75
34
CS Tube 300 4.00 0.00 0.00 OK OK 0.62 0.62
35
CS Tube 300 4.00 0.00 0.00 OK OK 0.62 0.62
36
CS Tube 260 4.00 0.00 0.00 OK OK 0.76 0.76
37
CS Tube 260 4.00 0.00 0.00 OK OK 0.75 0.75
38
CS Tube 220 4.00 0.00 0.00 OK OK 0.88 0.88
39
CS Tube 180 4.00 0.00 0.00 OK OK 0.63 0.63
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Table 6Member Details Report from Bridge Designer 2016 for the Warren Truss Bridge Member with the
Highest Compression (or Tension) Force/Strength Ratio
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Table 7 Load Testing Results for the Warren Truss Bridge
EDSGN Team # Warren Truss Bridge Weight
(grams)
Bridge Weight (lbs.)
Load at Failure (lbs.)
Structural Efficiency
1 85.1 0.188 40.2 214
2 78.6 0.173 63.3 366
3 77.2 0.170 58.8 346
4 76.2 0.168 107.8 642
5 75.0 0.165 74.5 452
6 85.2 0.188 48.0 255
7 87.0 0.192 82.2 428
8 80.6 0.178 32.4 182
Minimum = 182Maximum = 642
Range = 460Average = 361
Geomean = 334
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Table 8Load Testing Results for the Howe Truss Bridge
EDSGN Team # Howe Truss Bridge Weight (grams)
Bridge Weight (lbs.)
Load at Failure (lbs.)
Structural Efficiency
1 71.9 0.159 48.1 303
2 83.7 0.185 32.4 175
3 81.4 0.179 32.6 182
4 81.0 0.179 47.8 267
5 60.7 0.134 40.3 301
6 70.4 0.155 32.4 209
7 73.3 0.162 53.5 330
8 77.5 0.171 32.2 188
Minimum = 175Maximum = 330
Range = 155 Average = 244
Geomean = 237
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FIGURES
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Figure 1. Howe Truss Bridge Model from Bridge Designer 2016
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Figure 2. Warren Truss Bridge Model from Bridge Designer 2015
