why build a truss bridge
The reason the pratt truss is so common in steel bridges is because it tends to be more economical. this is because steel works better under tension than under compression. under tension, steel can theoretically operate very close to its yield stress.. A truss bridge is a bridge whose load-bearing superstructure is composed of a truss, a structure of connected elements usually forming triangular units.the connected elements (typically straight) may be stressed from tension, compression, or sometimes both in response to dynamic loads.the basic types of truss bridges shown in this article have simple designs which could be easily analyzed by. All these different truss patterns also factored into how beam bridges were being built. some takes featured a through truss above the bridge, while others boasted a deck truss beneath the bridge.. a single beam spanning any distance undergoes compression and tension.. 
why build a truss bridge
