Southwest Mississippi RC&D Council

2001 COMPETITION RULES AND INSTRUCTIONS

DESCRIPTION:

The competition will consist of the construction and testing of a model timber bridge on the home site of each team.

ELIGIBILITY:

The competition is open to all student chapters of American Society of Civil Engineers and Forest Products Society in the United States and Canada. Joint and multiple entries from one school will be accepted.

COMPETITION SPECIFICATIONS:

Each contestant (team) will be required to design, build and test a bridge constructed from wood structural members. The wood used in this project must be from a commercially available species. Be sure to check out our list of more than two dozen links to wood products design data, technical values, specifications, treatment information, supplies, etc. on the main page for the competition.

WOOD TREATMENT:

All wood members must be treated to AWPA standards for "above ground use". See www.awpa.com for details on ordering publications or go to Western Wood Preservers Institute site, click on "retentions" at bottom of menu to left, then select preservative type for standards tables. NOTE: Since all the most common procedures for meeting AWPA standards require pre-treatment in a pressurized environment to attain adequate retention levels, the treatment type and process should be part of the bridge design process, rather than a post-treatment alternative. There are plenty of safe treatment materials available, so student safety should be considered, but not prohibitive.

DESIGN CRITERIA:

Design Span: 4 meters from center line to center line of supports. The maximum length of an individual piece in any member shall not exceed 2.1 meters. There is no length limitation on built-up and laminated members provided that the individual pieces, including plywood, used in making the member do not exceed the specified maximum length. Maximum width of supporting base plates is 60 mm. There is no length constraint on cables, straps, rods or other tensioning devices.

Horizontal and Vertical Clearances: 1.20 m and 0.90 m, respectively (see sketch).

Depth of Understructure: Maximum of 500 mm at center-span and 1000 mm at support base measured from bottom of deck to lowest point of support structure.

Test Load: 20 kN for 1 hour. (See test setup for location of loading blocks.)

Load Application and Deflection Measurements: The load will be applied in 4 equal increments of 5 kN each, with the full load of 20 kN being achieved in approximately 10 minutes. Maximum load should be reached in not less than 6 minutes nor more than 20 minutes. Deflection readings will be recorded at each 5kN load increment. Then, four deflection readings shall be recorded at 15-minute intervals during the 1-hour full-load duration. Deflection measurements shall be recorded using gauges positioned at the following 4 locations, as a minimum:

Midpoint of longitudinal beam predicted to experience maximum loading.

Underneath midpoint of the load point (1 of 4) selected for monitoring as being representative of the deck's weakest point.

Point in longitudinal beam immediately to the left (transversely) of selected load point.

Point in longitudinal beam immediately to the right (transversely) of selected load point.

Note that only one loading setup is required, however note that this loading setup must be moved transversely if needed to test bridge and its deck at their weakest points. Failure to monitor above 4 points or to move load setup transversely if required will result in disqualification. Failure of drawings and photos/video to clearly document these points will also cause disqualification.

Maximum Vertical Bridge Deflection: Maximum allowed bridge deflection is ten (10) mm as recorded at midspan of the longitudinal beam receiving the greatest loading. Subtraction from deflection due to compression of supports will not be allowed. If two (2) or more longitudinal beams are predicted to receive equal loading, select only one to monitor, or monitor all such beams and submit average deflection (contestant's choice).

Maximum Vertical Deck Deflection: Maximum allowed net deck deflection is maximum deck span length divided by 400. Deck deflection shall be measured under the centroid of the loading point where the deck is calculated to experience maximum deflection under full loading. Deck deflection shall be adjusted by subtracting the average of the deflections recorded in the two longitudinal beams immediately transverse to each side of the selected loading point. See "Test Setup" sketch for details on placement of the four (4) loading points. Note that the loading points must be moved as a 4-point unit transversely as needed to assure that the above monitored load point (for deck deflection) is over the point where maximum deck deflection is expected.

The selected loading point must be at the deck's weakest point. It must be halfway between any transverse members such as floor beams, deck stiffeners, cross-bracings, diaphragms, etc. that make contact with the deck's underneath surface. It must also be halfway between any adjacent longitudinal support members. Required photographs and drawings of test setup, both from a side and end view, must be adequate to confirm location of the monitored load point and the location of gauges used to measure deflection in adjacent longitudinal beams (see Drawings). All deck spans will be measured in a transverse direction (inside to inside of adjacent longitudinal support beams). Since measuring actual maximum deck deflections and actual maximum transverse beam deflections would require multiple loading configurations, for this competition transverse beams that support a longitudinal deck will be considered a part of the deck. Therefore, longitudinal distance between adjacent transverse beams will not be used to calculate maximum vertical deck deflection.

Bridge Deck: The bridge deck does not have to be wood, but note 25% by weight nonwood restriction on total bridge weight. Any material can be used as long as it is designed to effectively transfer loads at all locations on its surface to the support structure, is not an open grid, can be treated to withstand weather-related deterioration, can withstand repetitive traffic loading and wear, and is capable of supporting the complete 4-load combination moved anywhere on the deck surface. In other words, it must work in real-life application! The maximum length per piece limit (2.1 meters) still applies to deck materials.

Prestressing: Prestressing will be allowed provided it is done 48 hours before testing.

Bridge Weight: Bridge must be weighed before testing and must include all bridge parts forming a part of the bridge as a structural system.

Curb: The curb does not need to resist a force but must be connected to the bridge. The curb may be a part of arch or truss members. Curb material must meet same requirements as Deck except for load bearing.

DOCUMENTATION:

Contestants will be required to submit by mail:

A VHS color video (maximum of 10 minutes) documenting all phases of bridge construction, weighing, loading, and test results at each loading increment and at the 15-minute intervals until the end of the one hour load duration. It is recommended to include within the frame of all video shots a labeling sign stating the significance and sequence of the picture in the testing procedures.

Photographs (Ideally 4" x 6" color prints, not color copies. Digital photos will be accepted as long as they are transmitted in .gif or .bmp format, are not larger than 640 X480 pixels in size and are scanned at 72 Dots Per Inch resolution.)
a. one side view from above plane of bridge deck
b. one end view from above plane of bridge deck
c. one end view of loading setup
d. one side view of loading setup
e. one group picture of design team either on the bridge or with bridge in foreground
f. (optional) no more than 4 pictures of the bridge construction process that show details not evident in above completed photos
Note: In pictures "a, b and e" above, try to avoid background and foreground clutter and be sure to save negatives, as an 8" x 10" enlargement may be requested of award-winning entries.

Drawings - Mail an 8 1/2-inch x 11-inch hard copy of bridge drawing(s) entered online. See Drawings requirements below.

Certification and Entry Form (print from website)

REPORT:

A technical report must be submitted online (via Internet) using templates provided and will include:

Abstracts: Using maximum of 500 words, explain the bridge design concept and explain what was done to optimize stiffness while attempting to minimize weight of the structure.
Table of all recorded test results of deflection measurements.
An itemized materials list showing weight of each item and total weight of bridge. The total weight of non-wood material must be less than 25% of the total weight of the bridge. Glue is non-wood.
A short summary (max. 500 words) describing the bridge and its behavior under load.
Drawings:
- Must show 3 views (plan or overhead, side or elevation, and end) or show 1 trimetric view (preferred!) if all required details can be shown,
- Must show location of the selected load point monitored for deck deflection and locations of all longitudinal beam gauge points, and
- Must be transmitted as e-mail attachments in either .jpeg (preferred) or .gif at size of approximately 640 x 480 pixels.
  NOTE: Be sure lettering is large enough to read easily on computer screen!

JUDGING:

A panel of three independent judges not affiliated with any contestant institutions will select the winners. Entries that do not meet all rules and performance criteria will be disqualified for consideration for Performance Awards but will be eligible to compete for Special Awards and Best Design. No single entry shall be eligible to receive more than three (3) awards.

AWARDS:

Willamette Industries Best Overall Design (1st-$1500, 2nd-$1000, 3rd-$500). This award is intended to reward intellectual effort, regardless of how the design meets the performance-related standards. Judged using following points:
- Design is a configuration of structural elements that can be optimized through normal engineering methods (20%)
- Design makes efficient use of structural materials (20%)
- Design is based on structural concepts that have broad applications (20%)
- Design shows intellectual efforts (20%)
- Judges' Review/Report (20%) (adequate documentation, clarity, neatness, content, abstract, photos, video)
Performance Awards

Maximum Bridge Deflection 50%
Total Bridge Weight 25%
Percent Nonwood (total bridge) 10%
Practical 5%
Economical 5%
Innovative 5%

Net Deck Deflection 50%
Total Bridge Weight 10%
Percent Nonwood (total bridge) 10%
Practical 10%
Economical 10%
Innovative 10%

Special Awards: (Each category: 1st-$500, 2nd-$350, 3rd-$200)
- Most Practical Design - Design that can be practical to implement in real-life design and construction; low-tech and easy to construct (low materials and labor costs).
- Most Aesthetic Design
- Most Innovative Design (in the use of new and non-traditional materials and/or construction methods)

DEADLINES:

Deadline for online entry (www.msrcd.org) is April 20, 2001. Deadline for receipt of mailed material (video, photographs, and drawings) is also April 20, 2001. Mail to SW Mississippi RC&D, 747 Industrial Park Rd., NE, Brookhaven, MS 39601. Enclose following information with mailed material:

College or University
Student Chapter name, address, phone, fax, e-mail
Faculty advisor
Contact person.

All materials received by RC&D will become the property of RC&D.

RESULTS:

Winners will be announced online by May 4, 2001. In addition, the full entries of all participants will be released online and available for all contestants as well as any Internet user to review. Each can learn from the successes and failures of others! The results will also be publicized through various publications.

ADDITIONAL INFORMATION:

Submit questions by e-mail to southwest@msrcd.org, or contact Bennie Hutchins, SW MS RC&D, phone 601-833-5539, fax 601-835-0054. Check Q&A/Updates regularly for valuable competition updates, rules clarifications, etc.