Bridges are affected by both internal and external forces. Internal forces occur within the bridge, through tension, compression, bending, etc. External forces are applied to the outside of the bridge, and can be static or dynamic. The static load of the bridge is the bridge itself, and the weight of its members and components. This is created by the force of gravity pulling on the members of the bridge. The dynamic load moves and changes, such as traffic, people, wind. It is created by the force of gravity on an object supported by the bridge. These forces can also be called 'dead' and 'live' loads. When these forces all act on a bridge at the same time it is pot under structural stress, and some parts can reach structural fatigue if too much pressure and load is placed on them for too long. Failure occurs when a member reaches its limit, and cannot support any more load, therefore breaking (Sansano, 2013).
The structural elements of the Waddell a-truss bridge include two trusses, which each have compressive and tensile components. The beams in the middle did not carry any immediate load, other than the one attached to the actual bucket. The way the load is placed meant that bars were in tension, …show more content…
One of the many bridge designs is the truss bridge, which works using both tension and compression forces. The Waddell a-truss was a simple truss to replicate using manila folders. Although the task of building the bridge was tedious, as all the components were cut meticulously to ensure the strongest bridge, the final result was quite amazing, as the bridge held double the mass required. In this experiment the bridge was built first, and separate members were tested separately, however if designing a bridge, or building a more difficult design these steps should be reversed. Therefore the testing could signify if a stronger bridge is required, or if the bridge is