8 th Grade Industrial Technology 8 th Grade Industrial Technology

Instructional Objective Students will be able to identify the three types of bridges Students will be able to identify the three types of bridges

Beam and Span Span the shortest distance (200 feet) Span the shortest distance (200 feet) Least expensive and most common Least expensive and most common

A beam bridge may be as simple as a log across an open span

The Beam Bridge A beam bridge is basically a rigid horizontal structure that is resting on two piers, one at each end. The weight of the bridge and any traffic on it is directly supported by the piers. The weight is traveling directly downward.

Simple Beam Bridge The pier at each end may also be called an abutment

Beam Bridges Modern beam bridges are good for short spans. CR North

Beam Bridges Scudders Falls Bridge For longer spans, a series of beam bridges may be put together. This is called a continuous span bridge.

Beam Bridge (Truss Design) Another type of beam bridge is known as the truss bridge. The truss bridge is made up of a framework consisting of straight bars (usually steel) that are arranged in triangular shapes.

Truss bridges are lighter weight and can have a longer span than solid beam bridges. This is because they distribute weight evenly. Truss Bridges

Dingman’s Ferry bridge crosses the Delaware River at the town of Dingman’s Ferry Truss Bridge

The Neversink Bridge is a simple truss bridge.

The Washington Crossing Bridge is an example of a continuous span truss bridge because it has more than one section.

The Calhoun Street Bridge from Morrisville to Trenton is also a continuous span truss bridge.

The Neversink Bridge is a simple truss bridge.

Arch over the roadway Arch under the roadway

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

They can be made of solid material such as stone or concrete.

Arch bridges can be strong enough to carry trains, such as this one near Yardley.

Suspension Used for spanning long distances up to 7000 feet Used for spanning long distances up to 7000 feet Most expensive Most expensive

Suspension bridges use large cables to suspend the roadway from above. Main Cable Roadway Cables Here is a view looking down from the top cable of the Golden Gate Bridge.

Suspension Bridges The main cables on the Golden Gate are about 3 feet in diameter

The Golden Gate Bridge in San Francisco is one of the most photographed bridges in the US.

The Golden Gate also has a section of trusses to add strength and stability.

The Cable Stay bridge is a suspension bridge without a main cable

Cable Stayed bridges are a more modern design

Large bridges may utilize more than one style Suspension Beam

Bridges Maximum Distance Spanned

Bridges Video Clip View the short video discussing the various types of bridges View the short video discussing the various types of bridges