In The Name Of In The Name Of AllahAllah

Mansoura Mansoura University.University.Faculty OfFaculty Of

Engineering.Engineering.Civil Eng . Dept.Civil Eng . Dept.

Report No ( 1)Report No ( 1)

Arch Arch BridgeBridge

ContentsContents11 - -OverviewOverview..

22 - -How do the abutments support an arch bridgeHow do the abutments support an arch bridge.?.?

33 - -Stone Arch BridgeStone Arch Bridge..

44 - -Concrete Arch BridgeConcrete Arch Bridge. .

55 - -Precast Concrete ConstructionPrecast Concrete Construction..

66 - -THE STONE ARCH BRIDGETHE STONE ARCH BRIDGE. .

77 - -THE KEYSTONETHE KEYSTONE. .

88 - -HOW TO BUILD AN ARCHHOW TO BUILD AN ARCH. .

99 - -Skew Arch BridgeSkew Arch Bridge. .

1010 - -THE ENDTHE END..

Arch BridgeArch Bridge

OverviewOverview

Arch bridges are one of the oldest typesArch bridges are one of the oldest types of of bridges and have great natural strength. bridges and have great natural strength. Instead of pushing straight down, the Instead of pushing straight down, the weight of an arch bridge is carried outward weight of an arch bridge is carried outward along the curve of the arch to the supports along the curve of the arch to the supports at each end. These supports, called the at each end. These supports, called the abutments, carry the load and keep the abutments, carry the load and keep the

ends of the bridge from spreading outends of the bridge from spreading out . .

The Romans developed considerable skill in The Romans developed considerable skill in constructing arches and many of their structures remain constructing arches and many of their structures remain intact today. However, they were not able to calculate intact today. However, they were not able to calculate the strength of their-arches although their knowledge of the strength of their-arches although their knowledge of geometry inherited from the Greeks led them to adopt geometry inherited from the Greeks led them to adopt semicircular spans. Their arches were constructedsemicircular spans. Their arches were constructed

of stone made into the form of wedge shaped of stone made into the form of wedge shaped segments, or voussoirs, built up side by side segments, or voussoirs, built up side by side on temporary timber supports until the top on temporary timber supports until the top piece at the crown of the arch is pushed piece at the crown of the arch is pushed hom(keystone). One of the most famous hom(keystone). One of the most famous examples of their handiwork is the Pont du examples of their handiwork is the Pont du Gard aqueduct near Nîmes, France. Built Gard aqueduct near Nîmes, France. Built before the birth of Christ, the bridge is held before the birth of Christ, the bridge is held together by mortar only in its top tier; the together by mortar only in its top tier; the stones in the rest of the structure stay stones in the rest of the structure stay together by the sheer force of their own together by the sheer force of their own

weightweight..

Modem arch bridges are built of concrete. Modem arch bridges are built of concrete. It is an effective way to transfer loads to It is an effective way to transfer loads to the ground where foundation conditions the ground where foundation conditions are adequate to resist horizontal loads. A are adequate to resist horizontal loads. A large nurnber of concrete arch bridges large nurnber of concrete arch bridges have been constructed in the 20th have been constructed in the 20th century in both in-situ reinforced century in both in-situ reinforced

concrete and precast concreteconcrete and precast concrete . .

Today materials like steel and pre-stressed Today materials like steel and pre-stressed concrete have made it possible to build concrete have made it possible to build longer and more elegant arches, including longer and more elegant arches, including a spectacular 1700 foot span in New River a spectacular 1700 foot span in New River Gorge, West Virginia. (More typically, Gorge, West Virginia. (More typically, modern arch bridges span between 200-modern arch bridges span between 200-800 feet.)800 feet.)

A prime consideration in the erection of A prime consideration in the erection of an arch bridge is the method of an arch bridge is the method of supporting the voussoirs during supporting the voussoirs during construction. The cost of staging construction. The cost of staging required to support the arch centering required to support the arch centering during the placing of the voussoirs during the placing of the voussoirs represents a substantial proportion of represents a substantial proportion of the cost of construction. Their design the cost of construction. Their design and construction therefore requires and construction therefore requires

detail investigationdetail investigation . .

How do the abutments support an How do the abutments support an arch bridgearch bridge??

Cut a strip of cardboard that's about one Cut a strip of cardboard that's about one inch by 11 inches. Gently bend the strip inch by 11 inches. Gently bend the strip so that it has a curve. Position the so that it has a curve. Position the cardboard on a table so that it resembles cardboard on a table so that it resembles an arch. Press down on the center of the an arch. Press down on the center of the arch. What happens to the ends of the arch. What happens to the ends of the

cardboardcardboard??

Next, place a stack of books at each end Next, place a stack of books at each end of the arch. Press again. Now what of the arch. Press again. Now what happens? Notice how the stacks of happens? Notice how the stacks of books act as abutments, keeping the books act as abutments, keeping the

ends of the arch from spreading apartends of the arch from spreading apart..

When supporting its own weight and When supporting its own weight and the weight of crossing traffic, every the weight of crossing traffic, every part of the arch is under compression. part of the arch is under compression. For this reason, arch bridges must be For this reason, arch bridges must be made of materials that are strong made of materials that are strong

under compressionunder compression . .

Stone arch bridgeStone arch bridge

Concrete arch bridgeConcrete arch bridge

Constructing an arch bridge can be Constructing an arch bridge can be tricky, since the structure is completely tricky, since the structure is completely unstable until the two spans meet in unstable until the two spans meet in the middle. The method of construction the middle. The method of construction of precast concrete arches is similar to of precast concrete arches is similar to the method of construction used during the method of construction used during

the Roman periodthe Roman period..

Wedge shaped precast concrete segments Wedge shaped precast concrete segments are used as voussoirs and these are built are used as voussoirs and these are built up side by side on temporary supports. up side by side on temporary supports. There are two basic methods of There are two basic methods of providing the temporary support system: providing the temporary support system: the provision of a supporting system the provision of a supporting system below the bridge and the use of a tower below the bridge and the use of a tower and stay system. Gladesville Bridge in and stay system. Gladesville Bridge in Sidney, Australia was constructed using Sidney, Australia was constructed using

hollow precast concrete segmentshollow precast concrete segments . .

They were placed on falsework They were placed on falsework supported from the ground. The supported from the ground. The false work was designed to false work was designed to accommodate a 80-foot 200-foot accommodate a 80-foot 200-foot navigation channel. A diagrammatic navigation channel. A diagrammatic representation of the construction of representation of the construction of an arch using a tower and a stay an arch using a tower and a stay system is shown in the figure belowsystem is shown in the figure below..

Precast Concrete ConstructionPrecast Concrete ConstructionThe most common form of precast The most common form of precast concrete bridge construction is with the concrete bridge construction is with the use of the conventional precast bridge use of the conventional precast bridge beams. Different types of precast beams. Different types of precast concrete decks and their structural concrete decks and their structural advantages have been dealt with other advantages have been dealt with other speakers on this course. The speakers on this course. The construction of these types does not in construction of these types does not in general require special techniques. general require special techniques. Their construction will therefore not be Their construction will therefore not be

consideredconsidered..

Precast segmental construction is widely Precast segmental construction is widely used for the construction of long bridges used for the construction of long bridges and viaducts with medium to long spans. and viaducts with medium to long spans. In this form of construction, segments In this form of construction, segments are manufactured in a casting yard near are manufactured in a casting yard near the site and then transported to their the site and then transported to their final position for assembly. During the final position for assembly. During the early stages of development of segmental early stages of development of segmental precast construction, the joints between precast construction, the joints between the segments were wet poured grout or the segments were wet poured grout or dry mortar packdry mortar pack. .

These type of joints enabled the These type of joints enabled the segments to be adjusted ensure that segments to be adjusted ensure that the bridge follows the correct the bridge follows the correct alignment. Modem segmental alignment. Modem segmental construction uses the match casting construction uses the match casting technique. In this method the technique. In this method the segments are cast against each other segments are cast against each other in the same relative order they will in the same relative order they will have in the final structure. No have in the final structure. No adjustment is therefore necessary adjustment is therefore necessary between the segments at assembly. between the segments at assembly. The joints are either left dry or The joints are either left dry or

skimmed with a layer of epoxy resinskimmed with a layer of epoxy resin..

Remember ThatRemember That!! !!

Arch bridges are one of the oldest types of Arch bridges are one of the oldest types of bridges and have been arounded for bridges and have been arounded for thousands of years. Arch bridges have thousands of years. Arch bridges have

great natural strengthgreat natural strength..

They were originally built of stone or brick They were originally built of stone or brick but these days are built of reinforced but these days are built of reinforced concrete or steel. The introduction of these concrete or steel. The introduction of these new materials allow arch bridges to be new materials allow arch bridges to be

longer with lower spanslonger with lower spans . .

Instead of pushing straight down, the Instead of pushing straight down, the load of an arch bridge is carried load of an arch bridge is carried outward along the curve of the arch to outward along the curve of the arch to the supports at each end. The weight the supports at each end. The weight is transferred to the supports at either is transferred to the supports at either

endend..

These supports, called the abutments, These supports, called the abutments, carry the load and keep the ends of carry the load and keep the ends of

the bridge from spreading outthe bridge from spreading out..

The load at the top of the key stone The load at the top of the key stone makes each stone on the arch of the makes each stone on the arch of the bridge press on the one next to it. This bridge press on the one next to it. This happens until the push is applied to happens until the push is applied to the end supports or abutments which the end supports or abutments which

are enbedded in the groundare enbedded in the ground. .

The ground around the abutments is The ground around the abutments is squeezed and pushes back on the squeezed and pushes back on the

abutmentsabutments..

THE STONE ARCH BRIDGETHE STONE ARCH BRIDGE

The Arch Bridge is very common. The Arch Bridge is very common. They were built with stone before They were built with stone before iron and steel bridges were iron and steel bridges were introduced. A good example is introduced. A good example is seen in the picture below. The seen in the picture below. The Romans used arch bridges Romans used arch bridges throughout Europe and many of throughout Europe and many of them are still standing today as them are still standing today as

they are very strongthey are very strong . .

THE KEYSTONETHE KEYSTONE The keystone is the most important The keystone is the most important stone in an arch bridge, without stone in an arch bridge, without this stone the arch would collapse. this stone the arch would collapse. The keystone holds the arch The keystone holds the arch

togethertogether . .Draw a stone arch and label the Draw a stone arch and label the keystone. Explain why the keystone. Explain why the Keystone is very importantKeystone is very important..

HOW TO BUILD AN ARCHHOW TO BUILD AN ARCH

Before an arch can be built a wooden Before an arch can be built a wooden frame is built. This allows the stones frame is built. This allows the stones to be put in position. The frame is to be put in position. The frame is removed after the stones are in removed after the stones are in

positionposition..

EXAMPLES OF STONE ARCH EXAMPLES OF STONE ARCH BRIDGESBRIDGES

Skew Arch BridgeSkew Arch Bridge

THE THE ENDEND