final ideas

preliminary ideas

research & investigation

truss types

Howe Truss

The Howe truss is made up of vertical and diagonal members. The diagonal members of this type of bridge slope towards the center of the bridge in an upward manner.

Pratt Truss

The design of the Pratt truss is similar to that of the Howe truss, except for the diagonals that slope downwards in the former. Caleb and Thomas Pratt invented the Pratt truss in the year 1844. The maximum length of this bridge can be 250 feet and it is commonly used as a railway bridge.

research & investigation

 FORCES

compression:
 compresion is the force that squeezes a material together. when a material is in compression it tends to become shorter.

tension/streaching:
 tension is a force that streches a material apart.when a material is tension it means that that the material tends to strech or get bigger.

twisting: torsion or twisting is an action that twists the material.

shear: shear/ or sliding is a force that causes a part of material to slide past one another in opositte directions. 

research & investigation

has great natural strength. Thousands of years ago, Romans built arches out of stone. Today, most arch bridges are made of steel or concrete, and they can span up to 800 feet.

 a truss bridge consists of an assembly of triangles. Truss bridges are  commonly made from a series of straight, steel   bars.

 suspension bridges can span 2,000 to 7,000 feet -- way farther than any other type of bridge! Mostsuspension bridges have a truss system beneath the roadway to resist bending and twisting.

beam bridges consists of a horizontal beam supported at each end by piers. The weight of the beam pushes straight down on the piers. The farther apart its piers, the weaker the beam becomes