AY Honors/Bridges/Answer Key/es

Puentes
Asociación General Artes y Habilidades Manuales	Destreza: 1 Año de introducción: 2012

Requisitos

2. Describir las 6 clases principales de diseño de puentes y dar 2 ejemplos de cada uno:

a. Puente en arco

Dubai in the United Arab Emirates is currently building the Sheikh Rashid bin Saeed Crossing which is scheduled for completion in 2012. When completed, it will be the largest arch bridge in the world.

b. Beam bridge

Beam bridge in Germany

The northern approach ramps of the Fremont Bridge where it intersects with Interstate 5.

c. Cable-stayed bridge

Sutong Bridge over the Yangtze River

File:Antirio bridge evening.JPG

Rio-Antirio Bridge in Greece (fan shaped)

Rama VIII Bridge in Thailand (harp shaped)

d. Cantilever bridge

Forth Rail Bridge

Quebec Bridge, Quebec, Canada

A bridge built using cantilevers, structures that project horizontally into space, supported on only one end. For small footbridges, the cantilevers my be simple beams; however, large cantilever bridges designed to handle road or rail traffic use trusses built from structural steel, or box girders built from pre-stressed concrete. The steel truss cantilever bridge was a major breakthrough when first put into practice, as it can span distances of over 1,500 feet, and can be more easily constructed at difficult crossings by virtue of using little or no falsework.

e. Suspension bridge

The first permanent wire cable suspension bridge was Guillaume Henri Dufour’s Saint Antoine Bridge in Geneva in 1823, with two 40 meter spans. The first with cables assembled in mid-air in the modern method was Joseph Chaley’s Grand Point Suspendu in Fribourg, in 1834. The Otto Beit Bridge was the first modern suspension bridge outside the United States with parallel wire cables. Currently the longest suspended-deck suspension bridge in the world is the Akashi-Kaikyo Bridge in Japan, with a main span of 1991 meters.

f. Truss bridge

A Bailey bridge, used by the military around the world

Sky Gate Bridge R in Osaka, Japan

The ability to distribute the forces of compression, tension, shear and bending in various ways has led to a large variety of truss bridges. Modern materials such as pre-stressed concrete and fabrication methods, such as automated welding, and the changing price of steel relative to that of labor have significantly influenced the design of modern bridges.

Because wood was so abundant in the United States, early truss bridges would typically use carefully fitted timbers for members taking compression and iron rods for tension members, usually constructed as a covered bridge to protect the structure. Truss bridges became a common type of bridge built from the 1870’s through the 1930’s. As metal slowly started to replace timber, wrought iron bridges in the U.S. started being built on a large scale in the 1870’s. Bowstring truss bridges were a common truss design seen during this time, with their arched top chords. As the 1880’s and 1890’s progressed, steel began to replace wrought iron as the preferred material.

3. Discover the distance each of the following bridge designs can span:

We don't know what the maximum span distance is because engineers keep working better designs, but here are the longest existing bridge spans of each type and links to a list of bridges for each type so you can check for new longer bridge spans.

a. Arch bridge:

1. Longest masonry arch bridge Pont de la Libération, Villeneuve-sur-Lot, France 96m/315ft, completed in 1919
2. Longest completed arch bridge Chaotianmen Bridge Yangtze River, Chongqing, China 552 m/1,811 ft completed 2009

b. Beam bridge

Beam bridge spans rarely exceed 250 feet (76 m) long, as the flexural stresses increase proportional to the square of the length (and deflection increases proportional to the 4th power of the length). However, the main span of the Rio-Niteroi Bridge, Brazil, a box girder bridge, is 300 metres/980 ft.

c. Cable-stayed bridge

Cable-stayed bridges are good for up to about 1 km of span. The current longest cable-stayed bridge is the Russky Bridge over the Eastern Bosphorus Strait linking Vladivostok to Russky Island in Russia. Longest span 1104m/3622ft. or about 1.1 km. Opened in 2012. The Russky Bridge (photos) was criticised as a 'bridge to nowhere', costing about US$1 billion and serving an island where only 5,000 people live, althogh the design capacity is 50,000 cars a day. The paved road ends shortly after the bridge.

d. Cantilever bridge

The largest cantilever bridge in the world is the 549-metre/1,801 ft Quebec Bridge in Quebec, Canada The project failed twice, at the cost of 88 lives, and took over 30 years to complete. Opened December 3, 1919, and was the longest span of any bridge in the world until the Ambassador_Bridge between Detroit and Windsor was completed in 1929. It is still in use and also a National Historic Site. It is unlikely a longer one will ever be built as the suspension and cable-stayed designs are better for long distances.

e. Suspension bridge

The longest spans are suspension bridges, including the 17 longest bridge spans in the world, as of 2014. The current longest suspension bridge is the Akashi Kaikyō Bridge aka Pearl bridge in Kobe Japan at 1,991 metres/6,532 ft. It carries 6 lanes of traffic and opened in 1998.

f. Truss bridge

There are a wide variety of truss bridge designs and they are very common because they can be built from a wide variety of materials and use the material efficiently. They are good for short to medium crossings.

4. Name the bridge design that can span the longest distance.

Suspension bridge

5.Draw or illustrate the basic design of each of the following bridge types.

More information at Bridge Structure Types

a.Beam bridge

b.Arch bridge

c.Suspension bridge

d.Covered bridge

A covered bridge could use any of several underlying designs like Beam, Arch, or Truss but the key feature is that the travel lane(s) are enclosed by a covered structure. The covering protects wood bridges from decay, or can have other reasons for the cover in pedestrian models likes weather protection and space for shops. Draw a bridge with a roof and walls.

e.Truss bridge

f.Cable-stayed bridge (fan shape)

all cables collected at the top of the tower. Compare to cable-stayed harp shape below

g.Cantilever bridge

h.Bascule bridge

i.Cable-stayed bridge (harp shape)

Cables hung down the towers. Compare to the cable-stayed fan shape above

6. Do the following activities:

a. Watch a video about bridges.

• Deepest Sea Highway - Megastructures - Nat Geo Documentary
• Discovery Channel Hangzhou Bay Bridge
• Impossible Bridges- The Golden Gate Bridge
• The Brooklyn Bridge - Modern Marvels - History Channel Documentary

Or search for a video about an impressive bridge near you or one that interests you.

b. Make a list of at least eight notable bridges OR name two bridges that you have crossed and tell what design they are.

Have fun. This is one of the ways you demonstrate what you learned in the honor. Try doing this with Requirement 7.

7. Make a video/multimedia presentation or scrapbook presentation about bridge(s) you have seen.

This requirement does not specify the amount of information required, so use your common sensem Why not work on the scrapbooking honor too?

8. Build a bridge using materials such as craft sticks, toothpicks, yarn, thread, and glue.

Beam style pioneer bridge built with Lincoln Logs by JadeDragon & team

Directions can be found in such magazines as Popular Mechanic and craft manuals specific to “model wooden bridges.” There are extensive competitions that use wood craft sticks. Some bridges hold well in excess of 120 pounds!

This site that offers plans and kits. Use it to order a kit, or just for ideas.

The truly architecturally gifted Pathfinder might try to build a cardboard bridge over an actual river.

Popsicle stick bridges

Balsa wood bridge construction

Video of a working Bascule Bridge Model - totally replicable by an observant Pathfinder, while you will need some serious engineering expertise to build this model that won a contest in Bombay.

9. Recite John 3:16, then tell how this verse describes Jesus’ role as a bridge between heaven and earth.

“For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.”
-- John 3:16

Sin had placed an un-crossable gap between God and man. When God sent His Son to give His life for sinful man, a bridge was created by Jesus whereby man could once again be restored to his connection with God and heaven. By believing in God’s Son, each person has the opportunity to be re-connected to the sin-free life that God intended for humanity.

Ellen White regularly referred to both Christ and the Cross as a Bridge between mankind and heaven. For example "By transgression man was severed from God, the communion between them was broken; but Jesus Christ died upon the cross of Calvary, bearing in His body the sins of the whole world, and the gulf between heaven and earth was bridged by that cross. Christ leads men to the gulf, and points to the bridge by which it is spanned, saying, “If any man will come after me, let him deny himself, and take up his cross daily, and follow me (Luke 9:23)”" (Manuscript 21, 1895). {7BC 941.8} For more examples go to https://egwwritings.org/ and search "Christ bridge."