2020 NEPA Regional Bridge Building Competition Criteria

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These rules have been developed by the International Bridge Building Committee for the 2020 International Bridge Building Contest to be held on Saturday, May 9, 2020 in Chicago, IL, USA. These rules have also been adopted by the Northeast Pennsylvania Regional Bridge Building Competition to be held Saturday, February 22, 2020 (Snow Date TBD, 2020) at The Viewmont Mall in Dickson City, PA.

In order to receive official wood and participate in the contest, contact Paul Schneider by e-mail at [email protected]. Each school is limited to three bridges from 3 different competitors (NO TEAMS ARE PERMITTED). Students may participate in person, by proxy, or by mail entry.

Please visit our website www.neparbdgblg.com for specific suggestions and information relative to our competition. If you have any questions, please feel free to contact: Paul Schneider at [email protected].

The object of this contest is to see who can design, construct and test the most efficient bridge within the criteria established below. Model bridges are intended to be simplified versions of real-world bridges, which are designed to permit a load to travel across the entire bridge. In order to simplify the model bridge design process, the number of loading positions is reduced, and to allow the contest to proceed in a reasonable amount of time, only one loading position is actually tested. These simplifications do not negate the requirement that the bridge must be designed to accept a load at any of the positions. Bridges determined by the judges to not meet this requirement will be disqualified and tested as unofficial bridges. 

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1. Materials

1. The bridge must be constructed only from the official 3/32 inch square cross-section basswood included in the kit and any commonly available adhesive.
2. The official basswood may be notched, cut, sanded or laminated in any manner but must still be identifiable as the original basswood.
3. No other materials may be used. The bridge may not be stained, painted or coated in any fashion with any foreign substance.

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2. Construction

1. The bridge mass shall be no greater than 25.00 grams.
2. DELETED 10-Jan-2020 
3. The bridge (see Figure 1) must span a gap (S) of 300. mm, be no longer (L) than 400. mm, be no taller (H) than 80. mm above the upper support surface, and no wider (W) than 80. mm at the loading surface. 
   
4. ​The bridge must be constructed to provide a horizontal support for the load (see 3.4) at each of the three possible loading locations. Any portion of the structure above the loading plane must provide clearance for the plate and the loading rod above as well as for the rod projecting below the loading plate (see Figure 2).
5. The bridge must be constructed to allow a 48. mm diameter, 300. mm long pipe (1.5 inch schedule 40 PVC pipe) to be passed horizontally across the bridge with the pipe's lower surface on the loading plane (P) between 0. and 20. mm above the support surface. This pipe must touch all three loading locations simultaneously (see 3.4).
6. The bridge structure may project a maximum of (B) of 20. mm below the support surfaces (see Figure 1). ​

​3. Loading

1. On the day of the competition, the judges will decide which one of the three loading locations will be used; it will be the same for all bridges.
2. Competition loading will stop at 50. kg, loading will continue until bridge failure (see 4.5).
3. The load will be applied by means of a 40. mm square plate (see Figure 2) with a thickness (t) of at least 6. mm but less than 13. mm. A 9.53 mm (3/8 inch) diameter linkage is attached from above and below to the center of the plate. The plate will be horizontal and will be mounted with its edges parallel to the longitudinal axis of the bridge. Force will be applied to the loading plate by means of an apparatus shown schematically in Figure 3. The minimum initial load will be approximately 2. kg.
4. The load will be applied with the center of the plate at one of three (3) possible locations on the longitudinal axis of the bridge: The center, 40. mm to the right of center, and 60. mm to the left of center of the bridge span (see Figure 1). The three (3) loading locations must lie in the same horizontal plane (P). This loading plane must lie a distance (P) between 0. mm and 20. mm above the support surface.

4. Testing

1. On the day of the contest, contestants will center their bridge on the support surfaces. The judges will apply the loading plate and linkages to the selected loading position with two edges of the plate parallel to the longitudinal axis of the bridge and make attachments to the apparatus. The participant will be asked to affirm they agree the bridge has been positioned and loaded properly.
2. The loading plate will be lowered from above on the bridge at the selected loading location with two edges of the plate parallel to the longitudinal axis of the bridge.
3. The load will be applied through the loading rod (from below), as described in section 3 above. Competition loading will stop at 50. kg. However, loading will continue until bridge failure (see 4.5).
4. Bridge failure is defined as the inability of the bridge to carry additional load, or a load deflection of approximately 25.4 mm under the loading location, whichever occurs first. If a bridge has leg(s) which fail, the bridge will have failed regardless of deflection.
5. The bridge with the highest structural efficiency, E, will be declared the winner. Bridges failing above 50. kg will be considered to have held 50. kg for efficiency calculation.

E = Load supported in grams (50,000g maximum) / Mass of bridge in grams

5. Qualification

1. All construction and material requirements will be checked prior to testing and may be checked after testing. Bridges failing to meet these requirements will be disqualified. If physically possible, disqualified bridges may be tested as exhibition bridges at the discretion of the builder and the challenge director.
2. If, during testing, a condition becomes apparent (i.e., use of ineligible materials, inability to support the loading plate, bridge optimized for a single loading point, etc.) which is a violation of the rules or prevents testing as described above in Section 4, that bridge shall be disqualified. If the disqualified bridge can accommodate loading, it may still be tested as an exhibition bridge as stated above. 

Decisions of the judges are final; the above rules will not change for the Northeast Pennsylvania Regional Bridge Building Competition even if the International Rules are changed after our printing of this criteria unless posted here. If any changes occur after original posting ALL registered participants will be notified.

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Published: 05-Jan-2020   Revised: 10-Jan-2020 (Section 2.2 DELETED) 
2020 NEPA Regional Bridge Building Competition Criteria