Construction Methods and Materials: Burr Arch Truss - Essay Example

Moving loads create reversed stresses that are tackled through counter bracing. The bridge is designed to carry pedestrians, livestock, and vehicles. Short and medium spans are preferred for this structure. The material commonly used for this type of bridge is wood planks. The bridge is fixed and does not allow any movement. Burr Arch Truss is composed of an arch and several kingpost truss designs, fitting well for covered bridges.DesignIn the design, the arch bears all loads subjected to the bridge as the truss increases the rigidity of the bridge.

Although the kingpost can bear all loads, the design improves even the balance of dynamic loads traversing the bridge in the span. The design offers a stable structure that supports greater loads than an arch or a truss alone. The truss supports are pinned at the left end while the right end is roller supported. The arch is fixed at both ends making the structure immobile. There are two models of Burr-arch truss; flexible and rigid. The flexible model works on the assumption of pin connections at brace and post ends.

Its chords and arch are continuous, with fixed joints. For the rigid model, all joints are fixed. The load limitation of the structure is 44kN. Loads are applied at the midspan of the lower chord and transferred to the quarter points of the truss (Journal of Bridge Engineering 623).