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| College & Team Information | |||
| College or University: | Student Chapter: | ||
| Address: | |||
| Phone: | Fax: | E-mail: | |
| Website address: | Faculty Advisor: | ||
| Person In Charge of Project: | |||
| Team Member | Class | Team Member | Class |
| Hours spent on project: | Cost of Material ($ Amount) | ||
| Student: | Faculty: | Donated: | Purchased: |
| 1. Abstract - (Max 500 word narrative) | ||
| The main concepts behind the design of the bridge were to design a bridge with a low weight and high strength with minimal deflection keeping in mind that the design would need to be simple to construct. The materials for the bridge included the use of treated southern pine 2x4’s, 2x6’s, metal straps, and 16 d nails. The bridge design used a simple truss system along with a decking structure similar to a flooring system. The decking was built from 2x4’s with 2x6 joists. Blocking was used in between the joists to increase the stiffness. The truss allowed the bridge to maintain a high strength/low weight ratio while the decking system was easy to construct. Metal straps were used at the connections for an increase in stiffness without much of an increase in weight. Diagonal bracing was used to support the joists/decking with the main girders. The critical location of the design proved to be the tension member of the truss and the connections of the 2x6’s that created the main girders of the bridge. In order to improve the stiffness of these members, additional reinforcement was added at the connection of these members. | ||
| 2. Deflection Table | ||||||
| Deflection (millimeters - rounded to 2 decimal places) | ||||||
| Loading Inc. | Bridge | Beam L | Beam R | Average (L&R) | Gross Deck | Net Deck |
| 5 kN | ||||||
| 10 kN | ||||||
| 15 kN | ||||||
| 20 kN - 0 min. | ||||||
| 20 kN - 15 min. | ||||||
| 20 kN - 30 min. | ||||||
| 20 kN - 45 min. | ||||||
| 20 kN - 60 min. | ||||||
| 1) Loading Increments. | ||||||
| 2) Bridge - As measured at midspan of the longitudinal beam receiving greatest loading. | ||||||
| 3) Beam L - As measured under the longitudinal beam to left of selected deck monitoring point. | ||||||
| 4) Beam R - As measured under the longitudinal beam to right of selected deck monitoring point. | ||||||
| 5) Average (L&R) - Average of 3 and 4. | ||||||
| 6) Gross Deck - As measured under the loading point expected to experience maximum deflection. | ||||||
| 7) Net Deck - Column 6 minus column 5. | ||||||
| Deck span (transverse distance between main longitudinal bridge support members measured from inside edge to inside edge) = mm / 100 = mm (max. allowable net deck deflection) | ||||||
| 3. Materials List | |
| Material Item | Weight (kg) |
| Total Weight (Kg) | |
| Weight Non-wood (Kg) | |
| Percent Non-wood | |
| 4. Summary -Describe Bridge and behavior under load - (Max 500 words) | ||
| At the time of testing, the bridge was loaded in four equal increments as required for testing. Once the full load of 20 kN was applied, a small deflection became visually noticeable over the bridge span. Closer observation of the bridge, detected some wood members splitting at the nailed connections. Other nailed connections appeared to be pulling loose, as a gap between wood members became noticeable. The handrail on each side of the bridge became stiff as these members were placed in compression. Also, the top horizontal component of the handrail appeared to bow slightly under the applied load. After testing was complete, the load was released and the bridge returned to its non-deflected shape. In general, the bridge behaved as expected during the testing procedure. | ||
| 5. Project Drawings and Photos | ||||
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| Longitudinal Cross Section | Tranverse Cross Section | Trimetric View | Project Photo | Team Photo |
| Click on drawing or photo above for larger view. | ||||
| 6. Component Details | ||
| In ten (10) words or less per each component below, describe the bridge: | ||
| Stringers/Girders: | Truss System, side supports | Deck: | 2x4 decking run parallel to bridge span |
| Floor Beams: | 2x6 stringers longitudinal to bridge span | |
| Suspension: | n/a | |
| Unique: | Truss System with top chord acting as handrail. | |
| Describe preservative treatment for all wood members. Include type and concentrations. Also include a short statement of why this treatment was selected. Did the treatment requirement present any special problems? If yes, provide details | ||
| All wood is pressure treated lumber and all nails/hangers are galvanized. These were selected because it is required to protect the members from outdoor elements. The treatment did not present any special problems. | ||
| 7. Special Considerations | ||
| N/A | ||
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Programming by:Keith Mazer
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