BRIDGES Objective: SWBAT learn how to plan, design, calculate, and construct a model of a bridge. Find out how mathematical concepts of ratio, proportion, and scale are implemented in the bridge building process.
Warm Up Assignment: • What is a bridge? • There are seven types of bridges. List all seven. • What is compression? • What is tension? • What is the difference between compression and tension?
Warm up Activity • Gather 9 popsicle sticks and a sheet of plain paper; • Make sure your table has white glue and wood glue; • Wait for further instructions;
Strength Test • Glue three popsicle sticks together using the same glue; • Repeat this process for all three types of glue (wood, white, and glue gun) • Sit your sticks aside and wait for them to dry.
Student Activity • Gather your glued set of popsicle sticks from last class period. • Sit at your desk and prepare to break your popsicle sticks.
Time To Break Them! • Grab your popsicle sticks at each end. • Bend them until they break! • Notice how easy or hard it is to separate your sticks!!!!
Let’s start building • Gather 20 popsicle sticks, a ruler, and a cutter. • Cut one rounded end and then measure four inches. Then cut at that point. • All your sticks must be the same length. • Use sandpaper to file your ends smooth.
Combine three sticks to make a long one. • Glue three sticks together using wood glue. • Then, glue another three sticks together using white glue. • Finally, glue three sticks together using the glue gun.
Introduction to Bridges • Bridges are essential to our everyday life and possibly some of the oldest examples of engineering available. • As early as 2000 years ago, the Romans built stone bridges to allow travel over bodies of water. Today, there are millions of bridges around the world that use different designs
Bridge: Definition • A bridge is a platform that spans over obstacles, valleys, canyons, and water. • A bridge extends a roadway across gullies, streams, rivers, and bays.
Types of bridges • Beam Bridge • Arch Bridge • Cable-Stayed Bridge • Truss Bridge • Movable Bridge (or a Draw Bridge) • Suspension Bridge • Cantilever Bridge
Types of Loads on Bridges • Static (Dead) • Dynamic (Live)
Definitions (Copy) • Dynamic or Live Load – Weight that moves or changes; A variable weight on a structure, such as moving traffic on a bridge. • Static or Dead Load – Weight that does not move; The invariable weight of a structure, such as a bridge. It may also include any permanent loads attached to the structure.
Types of Forces on Bridges • Tension • Compression • Torsion • Shear
Trusses • Trusses are triangulated frameworks used as spanning or bracing elements in buildings, bridges, transmission towers, and other structures. What distinguishes the truss from other structural forms is precisely its triangulation
Multiple Kingpost (MKP)The kingpost that forms the basis for this truss is found in the center two panels. The multiple form is the simplest and by far, the most common type in Ohio
Queenpost (Q)A three panel truss used for short spans, the queenpost was devised as an extension of the basic kingpost by placing a horizontal member in the center panel.
Burr Arch (B)Patented in 1804 by Theodore Burr of New York, this design combined a large arch with a multiple kingpost truss. The addition of an arch was a traditional way of strengthening an existing truss. Many of Ohio’s bridges were stiffened in this way.
Long (L)In 1830 Col. Stephen H. Long of the U.S. Topographical Engineers became the first American to use mathematical calculations to develop a truss. It became known as an "X" truss.
Town (T)Connecticut architect Thiele -Town received a patent for a truss of crisscrossed diagonals, or lattice, in 1820.
Howe (H)In 1840 Massachusetts builder William Howe introduced iron into wooden truss design by substituting adjustable iron rods for the vertical members of Long’s truss.
Smith (S)Tipp City, Ohio, native Robert W. Smith received truss patents in 1867 and 1869. Three different variations of his basic design still exist in Ohio’s bridges.
Partridge (P)Reuben L. Partridge of Marysville, Ohio, received a patent for a design that was remarkably close to Smith’s truss. He was especially active in Union County.
Childs (C)Developed in 1846 by Horace Childs, the Childs truss was used exclusively after 1883 by Ohio bridge builder Everett Sherman. The truss simply added diagonal iron rods to a multiple kingpost design.
Warren (W)Patented in 1848 by two Englishmen, one of whom was named James Warren, it utilizes isosceles triangles.
BRIDGE BUILDING ASSIGNMENT • In groups of two’s, log on to a computer station; • Go to the website on the worksheet: http://www.pbs.org/wgbh/buildingbig/bridge/challenge/index.html Write two paragraphs about the bridge challenge. Include how you completed the locations with their bridges.