The Neuqua Valley High School Bridge Building Contest will be held on Friday, January 9 , 2015. All th bridges must meet the rules specified below and must be checked in by Wednesday, January 7
, 2015 during class. The object of this contest is to see who can design, construct and test the most efficient bridge within these specifications. Model bridges are intended to be simplified versions of realworld bridges, which are designed to accept a load in any position and permit the load to travel across the entire bridge. Students who build a LEGAL bridge that is able to hold the 2 kg weight hanger will receive full credit on the assignment. Up to 1% extra credit will be added to this coursework grade for students based on the performance of the bridge during the contest.
a. The bridge must be constructed only from 3/32 inch square crosssection basswood and any commonly available adhesive.
b. The basswood may be notched, cut, sanded, or laminated in any manner.
c. No other materials may be used. The bridge may not be stained, painted or coated in any fashion with any foreign substance.
a. The bridge mass shall be no greater than 25.00 grams.
b. The bridge (see Figure 1) must span a gap (
) of 300. mm, be no longer (
) than 400. mm, have a height (
) between 50. mm and 100. mm above the support surfaces, and have a width (
) that is no longer than 70. mm. The bridge structure may not project below the support surfaces.
c. The bridge must be constructed to provide a horizontal support surface for the loading plate and rod at one loading position. This position is located at the midspan and top of the bridge.
This rule implies that the loading position and therefore midspan of the bridge must be the tallest point of the bridge. The bridge structure must allow the loading rod (see 3a) to be mounted from below.
a. The load will be applied downward, from below, by means of a 40. mm square plate (see
Figure 2) resting on the loading plane of the bridge. The plate will be 19. mm thick and will have a 9.53 mm (3/8 inch) diameter eyebolt attached from below at its center with a standard hex nut. Masses will be supported on a vertical loading rod suspended from the eyebolt. The sides of the plate will be parallel to the longitudinal axis of the bridge.
a. On the day of the contest, contestants will center their bridge on the loading surfaces. They will have previously located the loading plate and 3/8 inch eyebolt to the selected loading position. b. The load will be applied from below, as described in section 3 above. Loading will continue until bridge failure.
c. Bridge failure is defined as the inability of the bridge to carry additional load, or a load deflection of 25 mm under the loading location, whichever occurs first.