Famous bridges of the world : measuring length, weight, and volume

33 Pages·2005·21.512 MB·English

by  Maxwell, Yolonda

FAMOUS BRIDGES
OF THE WORLD
Measuring Length, Weight, and Volume
Yolonda Maxwell
PowerMathTM
The Rosen Publishing Group's
PowerKids Press1
TM
New York
Published in 2005 by The Rosen Publishing Group, Inc.
29 East 21st Street, New York, NY 10010
Copyright © 2005 by The Rosen Publishing Group, Inc.
All rights reserved. No part of this book may be reproduced in any form without permission
in writing from the publisher, except by a reviewer.
Book Design: Michael Tsanis
Photo Credits: Cover © Stephen Simpson/Taxi; p. 5 © Michael S. Yamashita/Corbis; p. 6 © Dallas and
John Heaton/Corbis; p. 9 © Tom Bean/Corbis; p. 10 © Robert Estall/Corbis; p. 13 © James Davis;
Eye Ubiquitous/Corbis; pp. 14-15 © Will and Deni Mclntyre/Corbis; p. 17 © Angelo Hornak/Corbis;
p. 19 © Alan Schein Photography/Corbis; p. 23 © Galen Rowell/Corbis; p. 25 © Robert Essel NYC/Corbis;
p. 27 © Bettman/Corbis; p. 28 © Raymond Gehman/Corbis; p. 30 © Jose Fuste Raga/Corbis.
Library of Congress Cataloging-in-Publication Data
Maxwell, Yolonda.
Famous bridges of the world : measuring length, weight, and volume / Yolonda Maxwell.
p. cm. — (PowerMath)
Includes index.
ISBN 1-4042-2937-X (library binding)
ISBN 1-4042-5137-5 (pbk.)
6-packlSBN 1-4042-5139-1
1. Mensuration—Juvenile literature. 2. Bridges—Juvenile literature. I. Title. II. Series.
QA465.M39 2005
516M5—dc22
2004007065
Manufactured in the United States of America
Contents
Engineering Marvels 4
Arch Bridges 7
Beam Bridges 14
Suspension Bridges 18
A Famous Failure 26
Cable-Stayed Bridges 29
More Bridge Math 30
Glossary 31
Index 32
Engineering Marvels
Bridges are such a familiar part of life today that we often take them
for granted. Have you ever considered what challenges engineers face when
building these structural marvels, or how our lives would be different without
them? To get an idea of how bridges affect your life, imagine a world where
there are no bridges.
Think about a bridge you cross often. Perhaps you cross one on your
way to school or to visit family or friends in other places. Without this bridge,
how would you get where you needed to go, and how long would it take you
to get there? (Don't imagine that you'd use another nearby bridge, because
there are no bridges anywhere.)
If you wanted to build a bridge, how would you go about it? What
would you need to know? Engineers need to know the properties of the
building materials they use. They also need math skills to calculate the
quantities of building materials they'll need. We can use our math skills to
learn about the lengths, weights, and volumes of materials that played a
part in the construction of some of the world's most famous bridges.
The earliest bridges were simple, sometimes no more than logs laid across streams
or gorges, or ropes stretched across rivers or valleys. This photograph, taken in the
1980s, shows people using an ancient rope bridge in southern China
4
5
weight
6
Arch Bridges
When engineers design bridges, they must make sure the bridge is
strong enough to support its own weight plus the weight of the traffic it will
carry. Many early bridge builders favored the arch bridge because of its great
strength. Instead of pushing straight down on the bridge's deck, the weight of
both traffic and the bridge is transferred outward along the curves of the arch
to the large supports at each end. These supports, called abutments, carry
the weight and keep the ends of the arch from spreading out.
Ancient Romans, who are still known today for their engineering feats,
built the structure shown on page 6 around 2,000 years ago. Located in
what is today southern France, the stone structure is both a bridge and an
aqueduct. This section over the Gard (GAHR) River is known by its French
name, Pont du Gard, which means "Bridge over the Gard."
The Pont du Gard has 3 levels, each with a series of arches.
A channel on the top level carried water to the city of NTmes (NEEM).
A road ran along the top of the lowest level.
The Pont du Gard is what remains of a structure that was
originally much longer. The ancient aqueduct stretched from
Nimes to a water source about 30 miles away.
7
The Gard River valley is wider at the top than at the bottom, so the
middle level of the Pont du Gard is longer than the bottom level, and the top
level is longer than the middle level. The bottom level is about 510 feet long
and has 6 large arches. The middle level is about 870 feet long and has
11 large arches. The top level has 35 small arches, each about 16 feet wide.
Each of the 36 pillars on the top level is about 9.5 feet wide. What is the total
length of the top level?
First, multiply 16 feet by 35 to Find Next, multiply 9.5 feet by 3G to find
the length of all the arches. the length of all the pillars.
16 feet per arch 9.5 feet per pillar
+ 35 arches + 36 pillars
80 570
+ 48 + 285
560 feet 342.0 feet
Finally, add these 2 products to find the length of the upper level
560 feet {length of arches}
+ 342 feet {length of pillars}
902 feet {total length}
The total length of the upper leve
Altogether, the Pont du Gard is about 160 feet high. It is built of
limestone blocks, some of which weigh as much as 4,000 pounds. The
blocks were cut so precisely and fit together so tightly that no cement was
needed to hold the stones in place.
8
•
The aqueduct carried enough water to provide each of the 440,000 people
in Nimes with about 100 gallons of water each day. How many gallons of
wafer did the aqueduct carry to Nimes every day? To find the answer,
multiply fhe number of people by the number of gallons per person.
9