BRIDGE BASICS Loudoun County Public Schools

Bridge Basics Loudoun County Public Schools-Free PDF

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Beam Bridges, eam bridges are the oldest known bridges and tend to be the simplest to design and build Roughly half of all bridges. B in the United States are beam bridges They consist of vertical piers and horizontal beams A beam bridge s strength. depends on the strength of the roadway and can be increased by adding additional piers While beam bridges can be quite. long the span or distance between adjacent piers is usually small. Pros and Cons of Beam Bridges,Pros Easy to build inexpensive relative to other. bridge types used widely in urban and rural settings. Cons Limited span large ships or heavy boat traffic. cannot pass underneath design generally not consid. ered very interesting or eye catching,Compression and Tension. Compression As live loads such as cars and trucks Walter B Jones Bridge Hyde County NC completed 1981 courtesy North Carolina Department. of Traffic,travel across the bridge the force of compression. acts on the top of the roadway and passes down,compression.
into the piers,tension roadway, Tension The force of tension acts on the underside. of the roadway which is pulled apart by the live loads. pressing down on the top of the roadway,pier pier pier. BRIDGE BRAG, It s the loooooooonnnnnnngest bridge in the world and it s a beam bridge The Lake Pontchartrain Causeway in Louisiana is. approximately 24 miles long and its twin spans are supported by more than 9 000 pilings. 2005 National Building Museum Bridge Essentials 29. Arch Bridges, rch bridges were built by the Romans and have been in use ever since They are often chosen for their strength and. A appearance It is the shape of the arch that gives the bridge its strength which is reinforced by placing supports or. abutments at its base Arch bridges can be built from various materials including wood stone concrete and steel The. famous Italian artist Leonardo da Vinci once said An arch consists of two weaknesses which leaning on each other. become a strength,Pros and Cons of Arch Bridges,Pros Wide range of materials can be used consid.
ered attractive very strong, Cons Relatively expensive typically designs are limited. to certain sites e g where the ground can support, the large forces at the base of the arch where the. span to depth ratio of the arch is proportional or. where an arch is visually appropriate Antietam Aqueduct Savage MD completed 1834 courtesy Lawrence Biemiller. Compression and Tension live load,compression,Compression The force of compression is greatest. at the top of the arch The abutments press against tension. the bottom of the arch preventing the bases of the keystone keystone. arch from being pushed outward, Tension The force of tension is strongest at the bot. tom of the arch and pulls the sides outward In gener. al the larger and shallower the arch the greater the. effects of tension and need for abutment support span span. abutment abutments abutment,BRIDGE BRAG, Montgomery Meigs the architect and engineer of the National Building Museum also designed the complex Washington.
aqueduct system It carries water from the Potomac River over the arched Cabin John Bridge in Maryland to two water pro. cessing plants in nearby Washington D C When the bridge was completed in 1863 it was the longest masonry arch in the. world It held the record for 40 years The main arch has a span of 220 feet rising 57 feet above a creek. 30 Bridge Basics 2005 National Building Museum,Truss Bridges. ooden truss bridges were used as early as the 1500s but the first metal one was completed in 1841 They are very. W strong and have been used for railroad bridges mainly because of the heavy loads that they can support A truss a. rigid support structure that is made up of interlocking triangles holds up the roadbed and is set between two piers The tri. angle is used because it is the only shape that is inherently rigid. Pros and Cons of Truss Bridges, Pros Very strong frequently used as a draw bridge or. as an overpass for railroad trains, Cons Difficult to construct high maintenance difficult. to widen if necessary generally not considered attractive. Compression and Tension,Compression As traffic pushes down on the road. George Street Bridge Aurora IN completed 1887 courtesy Indiana Department of Transportation. way compression acts on the upper horizontal mem,bers of the truss structure live load.
compression,Tension Tension acts on the bottom horizontal mem. bers of the truss structure The forces of tension and. compression are shared among the angled members,BRIDGE BRAG. It s difficult to see the trusses on some of America s best known truss bridges the covered bridges that were common in the. rural Northeast The roofs were not constructed to protect people from severe weather but to preserve the truss system. itself Wooden bridges without roofs would last 10 to 15 years but covering the bridge extended its life to 70 or 80 years. 2005 National Building Museum Bridge Essentials 31. Suspension Bridges, uspension bridges are strong and can span long distances One early bridge was designed and built in 1801 in Penn. S sylvania They are expensive because they take a long time to build and require a large amount of material They are. commonly found across harbors with a lot of boat traffic The primary elements of a suspension bridge are a pair of main. cables stretching over two towers and attached at each end to an anchor Smaller cables attached to the main cables support. the roadway,Pros and Cons of Suspension Bridges,Pros Span distances up to 7 000 feet considered. attractive allow large ships and heavy boat traffic to. pass underneath,Cons Expensive require a long time and a large.
amount of material to build, Golden Gate Bridge San Francisco CA completed 1937 used with permission from The Golden. Compression and Tension Gate Bridge Highway and Transportation District San Francisco CA www goldengatebridge org. Compression Traffic pushes down on the roadway, but because it is suspended from the cables the compression tower tower. weight is carried by the cables which transfer the. force of compression to the two towers, Tension The force of tension is constantly acting on cables cables. the cables which are stretched because the roadway. is suspended from them,anchor anchor,BRIDGE BRAG, The Tacoma Narrows suspension bridge in Washington State was known as Galloping Gertie because it rippled like a roller. coaster Completed in July 1940 the first heavy storm four months later caused the bridge to break and collapse from wind. induced vibrations It was replaced by a stiffer bridge which has proven to be satisfactory. 32 Bridge Basics 2005 National Building Museum,Cable Stayed Bridges.
he first modern cable stayed bridge was completed in Sweden in 1956 Cable stayed bridges were created as an. T economical way to span long distances This bridge s design and success were made possible as new materials and. construction techniques were developed Cable stayed bridges have one or more towers each of which anchors a set of. cables attached to the roadway,Pros and Cons of Cable Stayed Bridges. Pros Span medium distances 500 2 800 feet less, expensive and faster to build than suspension bridges. considered attractive,Cons Typically more expensive than other types of. bridges except suspension bridges,Compression and Tension. Fred Hartman Bridge Baytown Laporte TX completed 1995 courtesy Kevin Stillman Texas Depart. Compression As traffic pushes down on the road ment of Transportation. way the cables to which the roadway is attached, transfer the load to the towers putting them in com.
compression, Tension The force of tension is constantly acting on. the cables which are stretched because they are,attached to the roadway. live load live load,BRIDGE BRAG, America s longest cable stayed bridge the Cooper River Bridge in Charleston South Carolina opened in summer 2005 It is. approximately 2 5 miles long and 186 feet above the river The central span between the two towers is 1 546 feet and the. towers themselves rise 575 feet above the water line. 2005 National Building Museum Bridge Essentials 33. Don t Lose Reuse,Supply Request Sheet, Materials to Gather for the Engineering Bridges Lesson. Student s Name, During your upcoming lessons you will work in groups to create model bridges Please bring items from home.
to use as part of your bridge, U Paper towel or toilet paper rolls could be used as. piers for a truss bridge, U Oatmeal containers could be transformed into arches. for a bridge, Don t Lose U Narrow ribbons may become the cables on a. REUSE suspension or cable stayed bridge,U Small boxes and egg cartons could be used. to create pier and cars for a bridge,U Can you think of anything else.
WARNING Please avoid bringing milk cartons or containers that once held peanuts or peanut butter. Some people are highly allergic to these items, Using recycled materials to create bridges in this program helps to preserve the natural environment by promoting. reuse of objects rather than their disposal Such activities prevent filling landfill sites and polluting our environment. Other materials needed, Please bring clean recycled materials from home by date. 2005 National Building Museum Basic Program 49,Bridge Investigation Worksheet. Beam Bridges,LOOK at the beam bridge images on the poster. TEST the strength of the beam bridge card model using a stapler or another object of similar size. ANSWER the questions below using the images and model. Over WHICH obstacles do you commonly HOW do beam bridges work. find beam bridges,Review the areas of compression and tension.
check as many as are appropriate,roads highways live load. canyons valleys,creeks streams,WHAT are two pros and cons of beam. compression tension live load,Pros positive aspects of the bridge. WHY do architects and engineers build,beam bridges. easily span short distances,span long distances,check as many as are appropriate.
Cons negative aspects of the bridge,easy to build,engineering challenge. cost effective,allow large ships to pass underneath. appearance,50 Bridge Basics 2005 National Building Museum. Bridge Investigation Worksheet,Arch Bridges,LOOK at the arch bridge images on the poster. TEST the strength of the arch bridge card model using a stapler or another object of similar size. ANSWER the questions below using the images and model. Over WHICH obstacles do you commonly HOW do arch bridges work. find arch bridges,Review the areas of compression and tension.
check as many as are appropriate,roads highways,canyons valleys. creeks streams,WHAT are two pros and cons of arch,compression tension live load. Pros positive aspects of the bridge,WHY do architects and engineers build. arch bridges,easily span short distances,span long distances. check as many as are appropriate,Cons negative aspects of the bridge.
easy to build,engineering challenge,cost effective. allow large ships to pass underneath,appearance,2005 National Building Museum Basic Program 51. Bridge Investigation Worksheet,Truss Bridges,LOOK at the truss bridge images on the poster. TEST the strength of the truss bridge card model using a stapler or another object of similar size. ANSWER the questions below using the images and model. Over WHICH obstacles do you commonly HOW do truss bridges work. find truss bridges,Review the areas of compression and tension. check as many as are appropriate,roads highways live load.
canyons valleys,creeks streams,WHAT are two pros and cons of truss. compression tension live load,Pros positive aspects of the bridge. WHY do architects and engineers build,truss bridges. easily span short distances,span long distances,check as many as are appropriate. Cons negative aspects of the bridge,easy to build,engineering challenge.
cost effective,allow large ships to pass underneath. appearance,52 Bridge Basics 2005 National Building Museum. Bridge Investigation Worksheet,Suspension Bridges, LOOK at the suspension bridge images on the poster. TEST the strength of the suspension bridge card model using a stapler or another object of similar size. ANSWER the questions below using the images and model. Over WHICH obstacles do you commonly HOW do suspension bridges work. find suspension bridges,Review the areas of compression and tension. check as many as are appropriate,roads highways,canyons valleys.
creeks streams,WHAT are two pros and cons of,compression tension live load. suspension bridges,Pros positive aspects of the bridge. WHY do architects and engineers build,suspension bridges. easily span short distances,span long distances,check as many as are appropriate. Cons negative aspects of the bridge,easy to build,engineering challenge.
cost effective,allow large ships to pass underneath. appearance,2005 National Building Museum Basic Program 53. Bridge Investigation Worksheet,Cable Stayed Bridges. LOOK at the cable stayed bridge images on the poster. TEST the strength of the cable stayed bridge card model using a stapler or similar size object. ANSWER the questions below using the images and model. Over WHICH obstacles do you commonly HOW do cable stayed bridges work. economical way to span long distances This bridge s design and success were made possible as new materials and construction techniques were developed Cable stayed bridges have one or more towers each of which anchors a set of

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