bridges the science and art of the worlds most inspiring structures mar 2010

[...]... replace the two blocks by one new solid block which is made of the same material and is the size of the two blocks together Again the obstruction prevents the lower part of this new block from moving When you push against the top part of the new block you are doing exactly the same thing as when there were two blocks except they are now joined together The material of the block is holding the two parts... lengths of rope and pieces of steel or other materials used in a real bridge to find out how strong they are The internal force is acting all along the length of the rope from one of the teams to the other We could have made our cut anywhere along its length and used the same argument So we call the force an axial tension it is acting axially along the length of the rope The cross section of the rope... that they inspired the nursery rhyme ‘London Bridge is falling down’ 10 BRIDGES ARE BATS Ancient bridges upset the river gods and had to be placated, often with human sacrifice From river fords and stepping stones to the first bridges of simple tree trunks and stone slabs; from the Forth Railway Bridge to the Millau Viaduct in France, the story of bridges is as much the story of the people who built them... leap? 1 BRIDGES ARE BATS Arup is one of the leading firms of structural engineers in the world They knew that when they had a wobbly bridge, they just had to put it right and they did so It’s now as steady as a rock and a real landmark The reason for the wobble is interesting I was part of the crowd invited to test the bridge before it was reopened in 2002 Several hundred of us processed back and forth... like a book As we do so the story of bridges that will evolve has many interwoven strands of artistic, technical, scientific, and cultural development As we sift out the letters, words, sentences, paragraphs, and chapters of the book of a bridge and delve into the grammar of bridge structures we will begin to appreciate their aesthetic, historic, social, and engineering value Bridges aren’t just built... view of the cut The area of the cross section of your rope is quite small In a real bridge with lengths of steel or timber in tension the area of a cross section will be much larger and the internal force may not be exactly along the axis of the member As we shall see a little later, the action of the axial force can also be 14 BRIDGES ARE BATS described by saying that the rope has just one ‘degree of. .. Yet bridges are also a form of functional public art they can delight or be an eyesore Now architects and sculptors can and do contribute to the aesthetics of bridges to improve their impact in our public spaces One of the finest examples is the Millau Viaduct in France which certainly has the ‘wow’ factor xv INTRODUCTION Bridge building is a magnificent example of the practical and everyday use of science. .. more so recently The effect is to improve their impact on our public spaces The final outcome is a real team effort involving many different forms of creativity Bridges are links; they connect people and communities They enable the flow of people, traffic, trains, water, oil, and many other goods and materials Bridges therefore contribute to our personal well-being and our quality of life They can help whole... push Pat Dallard, the engineer at Arup who was a leading member of the team who developed the new theory, says that you change the way you walk to match what the bridge is doing It’s rather like walking on a rolling ship deck you move one way and then the other to compensate for the roll The way people walk doesn’t have to match exactly the natural frequency of the bridge as in resonance the interaction... bridge is whether it works effectively Bridges stand up because the basic structural components interact and work effectively with each other The foundations, strength, and effectiveness of the aesthetic, social, and cultural aspects of bridges are much more difficult to capture but are nonetheless very important Bridges are described in many different ways If you were to attempt to capture all of the types .