1. Replacement of Vehicle Bridge over Spring Creek
Design Project #1
Replacement of Vehicle Bridge over Spring Creek
Centre County, PA
Introduction to Engineering Design
EDGSN 100 Section 002
Family First Designs
Team 5
Shelby Quick
Carolyn Baker
Ricardo Branco
John Guglielmi JD
Presented to:
Prof. Berezniak
Spring 2016

2. Statement of Problem
Local flooding has destroyed a structurally deficient bridge located over Spring Creek in College Township, Centre County, PA (Pennsylvania Department of Transportation (PennDOT) Engineering District 2-0).
The destroyed bridge is along a heavily traveled local road and is designated as a vital lifeline for vehicle access to the Mount Nittany Medical Center located in State College, PA.
All traffic must now be re-routed more than 10 miles around the destroyed bridge, disrupting residential traffic flow and local commerce
Re-routing traffic puts State College residents at risk because police and emergency vehicles do not have easy access to that area of College Township, and residents of College Township do not have easy access to the Mount Nittany Medical Center. JD 2

3. Objective
PennDOT Engineering District 2-0 has initiated an emergency, fast-track project to expedite the design a new vehicle bridge over Spring Creek to replace the bridge destroyed by the recent extreme flood event.
Carolyn 3

4. Design Criteria Established design criteria: standard abutments
no piers (one span)
deck material shall be medium strength concrete (0.23 meters thick)
no cable anchorages
designed for the load of two AASHTO H20-44 trucks (225kN): one in each traffic lane
Bridge deck elevation: 20 meters
Deck span: 40 meters.
Both a Warren through truss bridge and a Howe through truss bridge shall be analyzed.
All other design criteria, such as steel member type, steel cross section type, and steel member size, shall be selected by each EDSGN100 design team.
Carolyn 4

5. Technical Approach Phase 1: Economic Efficiency
Economic efficiency (cost) shall be determined using the Engineering Encounters Bridge Design 2015 (EEBD 2015) software based on the specified requirements, constraints, and performance criteria.
The design objective is to use EEBD 2015 to design a stable Warren and Howe through truss bridge that has been optimized to keep the cost as low as possible
The replacement bridge must support its own weight (dead load), plus the weight of a standard truck loading (live load).
Carolyn 5

6. Technical Approach Phase 2: Structural Efficiency
A prototype (i.e., a scale model bridge) bridge shall be designed and built for both a standard Warren through truss bridge and a standard Howe through truss bridge by each design team.
Each prototype bridge shall be load tested in the lab to catastrophic failure.
The truss bridge type that exhibits the best structural efficiency (ability to safely dissipate live loads) shall be determined.
Structural Efficiency (SE) is calculated by dividing the load the bridge supports at catastrophic failure by the bridge weight.
The weight of each bridge type shall also be calculated (estimated) based upon a weight study of typical bridge members. Both the weight of the prototype bridges and the load at failure shall also be accurately measured and recorded.
Ricardo 6

7. Results Phase 1: Economic Efficiency
The main objective of the group was to both reduce the cost of every member and experiment with different materials while still maintaining the expected structural efficiency for both bridges.
After settling on the optimal design by just manipulating these two factors, the group attempted to make members of the same materials more extensively in order to reduce the production prices.
The material choice for respective members for both groups were relatively different, based on the distribution of force applied from the load. While in the Howe bridge, the highest discrepancy of materials was noted between top chords and bottom chords, the Warren bridge posses higher quality materials in the center members.
Ricardo 7

8. Results Phase 2: Structural Efficiency
Howe structural efficiency: 311
Geometric mean of efficiencies: 318
Maximum structural efficiency: 555 (Team 6)
Overall, the Howe prototype bridge ranked around the middle of the class in terms of weight, load, and structural efficiency.
Warren structural efficiency: 440
Geometric mean of efficiencies: 388
Maximum structural efficiency: 732 (Team 6)
Overall, the Warren prototype bridge ranked slightly higher than average in terms of load and structural efficiency, and it ranked slightly lower than average in terms of weight (heavier than average).
Shelby 8

9. Best Solution
The best solution to this problem is to implement the Warren Truss Bridge design.
Warren Bridge cost: $205, ($467.67/SE)
Howe Bridge cost: $227, ($731.37/SE)
The Warren’s structural efficiency was much higher than the average and the geometric mean, while the Howe’s fell below both mean values.
Howe material cost: $121,
Warren material cost: $95,
The use of smaller components and the maximization of each member makes the construction of the Warren bridge much more feasible than that of the Howe.
The Warren design is more efficient in all three categories--economic, structural, and design--therefore making it the best solution.
Shelby 9

10. Conclusions
The Warren Bridge is more efficient in all three categories--economic, structural, and design.
Improving the prototype design by constructing level and parallel truss members will better reflect the structural efficiency of the final design.
Shelby 10

11. Recommendations
The Warren Bridge design is the definitive recommendation to replace the flood-destroyed bridge.
The next step in this process would be to address any discovered flaws in order to further perfect the design before implementation.
The results of the load testing forensic analysis can be utilized in order to finalize the design. JD 11