A2-Xue

By the experience of using WPBD I know that the single line up is the most effect way of building the bridge. This time with the K’nex I am also try to make a simple line bridge. I use 3.375’’ as my basic chord. I find out that the 3.375’’ is the most effect length. Short that that would cost a lot of the join and long that is too long that cannot hold enough weight. I use two different triangles in the middle. In the really middle are four small triangles and the one beside it is three. By the WPBD experience I got know that the middle is the place than get most of the force, so I put more chord to support the weight. On the side witch is not that much force I cut out some of part. 
  

side view

top view

 bridge hight =3.375

bridge length=23.625

cost of the bridge

At first I use all 1.125’’ chord as a base. Then I find out it is too short and also the K’NET connect is not work really well and it also cost a lot of more money. Then I change the 1.125 to 3.375. it use less chord than the 1.125. About the link part I first use all 360 degree grooved gusset plate. Then I find out that 180 degree grooved gusset plate can do the same job with lower lost. I lower my cost a lot by these two steps.

By design this bridge I get a basic idea what a K’nex bridge would look like. It is different that the WPBD. In the WPBD the program would allow you to change different length and size of the bridge. In the K’nex it only have same size and 5 length. It lowers the possibility to design a bridge. I did not have the chance to try the bridge and see how it works out. I think this bridge would be reasonable good.