Misplaced Pages

#249750

88-450: The Korea Meteorological Administration considers the Han to be frozen over when the 100-meter section of water between the second and fourth posts of the southern span freezes. Pontoon bridges were moored at the site of the modern bridge, but the Han had no fixed crossings until the nearby Hangang Railway Bridge was completed in 1900. Plans for a road bridge did not materialize until 1917, when

176-439: A floating bridge , uses floats or shallow- draft boats to support a continuous deck for pedestrian and vehicle travel. The buoyancy of the supports limits the maximum load that they can carry. Most pontoon bridges are temporary and used in wartime and civil emergencies. There are permanent pontoon bridges in civilian use that can carry highway traffic. Permanent floating bridges are useful for sheltered water crossings if it

264-420: A vacuum with gravity acting on it. Suppose that, when the rock is lowered into the water, it displaces water of weight 3 newtons. The force it then exerts on the string from which it hangs would be 10 newtons minus the 3 newtons of buoyant force: 10 − 3 = 7 newtons. Buoyancy reduces the apparent weight of objects that have sunk completely to the sea-floor. It is generally easier to lift an object through

352-471: A volume integral with the help of the Gauss theorem : where V is the measure of the volume in contact with the fluid, that is the volume of the submerged part of the body, since the fluid doesn't exert force on the part of the body which is outside of it. The magnitude of buoyancy force may be appreciated a bit more from the following argument. Consider any object of arbitrary shape and volume V surrounded by

440-675: A 100-meter-long pontoon bridge during the Battle of Berezina to allow the Grande Armée to escape to safety. During the Peninsular War the British army transported "tin pontoons" that were lightweight and could be quickly turned into a floating bridge. Lt Col Charles Pasley of the Royal School of Military Engineering at Chatham England developed a new form of pontoon which was adopted in 1817 by

528-518: A deck built of balk, which were square, hollow aluminum beams. An Engineer Light Ponton Company consisted of three platoons: two bridge platoons, each equipped with one unit of M3 pneumatic bridge, and a lightly equipped platoon which had one unit of footbridge and equipment for ferrying. The bridge platoons were equipped with the M3 pneumatic bridge, which was constructed of heavy inflatable pneumatic floats and could handle up to 10 short tons (9.1 t); this

616-403: A fluid or liquid, is buoyed up by a force equal to the weight of the fluid displaced by the object. Archimedes' principle allows the buoyancy of any floating object partially or fully immersed in a fluid to be calculated. The downward force on the object is simply its weight. The upward, or buoyant, force on the object is that stated by Archimedes' principle above. Thus, the net force on the object

704-495: A hazardous manner from the swell, from a storm, a flood or a fast moving load. Ice or floating objects ( flotsam ) can accumulate on the pontoons, increasing the drag from river current and potentially damaging the bridge. See below for floating pontoon failures and disasters. In ancient China , the Zhou dynasty Chinese text of the Shi Jing ( Book of Odes ) records that King Wen of Zhou

792-607: A horse across the Bay of Baiae". Caligula's construction of the bridge cost a massive sum of money and added to discontent with his rule. During the Middle Ages, pontoons were used alongside regular boats to span rivers during campaigns, or to link communities which lacked resources to build permanent bridges. The Hun army of Attila built a bridge across the Nišava during the siege of Naissus in 442 to bring heavy siege towers within range of

880-480: A large floating pontoon bridge at Lanzhou (constructed earlier in 1372) as he crossed the Yellow River on this day. He wrote that it was: ... composed of twenty three boats, of great excellence and strength attached together by a long chain of iron as thick as a man's thigh, and this was moored on each side to an iron post as thick as a man's waist extending a distance of ten cubits on the land and planted firmly in

968-795: A large pontoon bridge built across the Yangtze River in 974 in order to secure supply lines during the Song dynasty 's conquest of the Southern Tang . On October 22, 1420, Ghiyasu'd-Din Naqqah , the official diarist of the embassy sent by the Timurid ruler of Persia , Mirza Shahrukh (r. 1404–1447), to the Ming dynasty of China during the reign of the Yongle Emperor (r. 1402–1424), recorded his sight and travel over

SECTION 10

#1732837500250

1056-449: A liquid. The force the liquid exerts on an object within the liquid is equal to the weight of the liquid with a volume equal to that of the object. This force is applied in a direction opposite to gravitational force, that is of magnitude: where ρ f is the density of the fluid, V disp is the volume of the displaced body of liquid, and g is the gravitational acceleration at the location in question. If this volume of liquid

1144-573: A long pontoon bridge built 1943 in Hobart , Tasmania was only replaced after 21 years. The fourth Galata Bridge that spans the Golden Horn in Istanbul , Turkey was built in 1912 and operated for 80 years. Provisional and lightweight pontoon bridges are easily damaged. The bridge can be dislodged or inundated when the load limit of the bridge is exceeded. The bridge can be induced to sway or oscillate in

1232-520: A pontoon bridge across the Arno during the siege of Pisa in 1406. The English army of John Talbot, 1st Earl of Shrewsbury crossed the Oise across a pontoon bridge of portable leather vessels in 1441. Ottoman engineers built a pontoon bridge across the Golden Horn during the siege of Constantinople (1453) , using over a thousand barrels. The bridge was strong enough to support carts. The Ottoman Army constructed

1320-617: A pontoon bridge at the Battle of Mohi in 1241 to outflank the Hungarian army. The French army of King Louis IX of France crossed the Charente on multiple pontoon bridges during the Battle of Taillebourg on 21 July 1242. Louis IX had a pontoon bridge built across the Nile to provide unimpeded access to troops and supplies in early March 1250 during the Seventh Crusade . A Florentine army erected

1408-564: A pontoon bridge during the siege of Rhodes (1480) . Venetian pioneers built a floating bridge across the Adige at the Battle of Calliano (1487) . Before the Battle of Worcester , the final battle of the English Civil War , on 30 August 1651, Oliver Cromwell delayed the start of the battle to give time for two pontoon bridges to be constructed, one over the River Severn and the other over

1496-555: A pontoon bridge to cross the Po river prior to the Battle of Montebello (1800) . Napoleon 's Grande Armée made extensive use of pontoon bridges at the battles of Aspern-Essling and Wagram under the supervision of General Henri Gatien Bertrand . General Jean Baptiste Eblé 's engineers erected four pontoon bridges in a single night across the Dnieper during the Battle of Smolensk (1812) . Working in cold water, Eblé's Dutch engineers constructed

1584-463: A series of cross planks called chesses to form the road surface, and the chesses were secured with side guard rails . A floating bridge can be built in a series of sections, starting from an anchored point on the shore. Modern pontoon bridges usually use pre-fabricated floating structures. Most pontoon bridges are designed for temporary use, but bridges across water bodies with a constant water level can remain in place much longer. Hobart Bridge ,

1672-515: Is achieved when these two weights (and thus forces) are equal. The equation to calculate the pressure inside a fluid in equilibrium is: where f is the force density exerted by some outer field on the fluid, and σ is the Cauchy stress tensor . In this case the stress tensor is proportional to the identity tensor: Here δ ij is the Kronecker delta . Using this the above equation becomes: Assuming

1760-408: Is equal to the weight of the fluid displaced by the immersed part of the body(s). Consider a cuboid immersed in a fluid, its top and bottom faces orthogonal to the direction of gravity (assumed constant across the cube's stretch). The fluid will exert a normal force on each face, but only the normal forces on top and bottom will contribute to buoyancy. The pressure difference between the bottom and

1848-407: Is equal to the weight of the fluid displaced by the object, or the density ( ρ ) of the fluid multiplied by the submerged volume (V) times the gravity (g) We can express this relation in the equation: where F a {\displaystyle F_{a}} denotes the buoyant force applied onto the submerged object, ρ {\displaystyle \rho } denotes

SECTION 20

#1732837500250

1936-408: Is not considered economically feasible to suspend a bridge from anchored piers . Such bridges can require a section that is elevated or can be raised or removed to allow waterborne traffic to pass. Pontoon bridges have been in use since ancient times and have been used to great advantage in many battles throughout history, such as the Battle of Garigliano , the Battle of Oudenarde , the crossing of

2024-405: Is replaced by a solid body of exactly the same shape, the force the liquid exerts on it must be exactly the same as above. In other words, the "buoyancy force" on a submerged body is directed in the opposite direction to gravity and is equal in magnitude to The net force on the object must be zero if it is to be a situation of fluid statics such that Archimedes principle is applicable, and is thus

2112-424: Is the difference between the magnitudes of the buoyant force and its weight. If this net force is positive, the object rises; if negative, the object sinks; and if zero, the object is neutrally buoyant—that is, it remains in place without either rising or sinking. In simple words, Archimedes' principle states that, when a body is partially or completely immersed in a fluid, it experiences an apparent loss in weight that

2200-425: Is the mass density of the fluid. Taking the pressure as zero at the surface, where z is zero, the constant will be zero, so the pressure inside the fluid, when it is subject to gravity, is So pressure increases with depth below the surface of a liquid, as z denotes the distance from the surface of the liquid into it. Any object with a non-zero vertical depth will have different pressures on its top and bottom, with

2288-401: Is used for example in describing the measuring principle of a dasymeter and of hydrostatic weighing .) Example: If you drop wood into water, buoyancy will keep it afloat. Example: A helium balloon in a moving car. When increasing speed or driving in a curve, the air moves in the opposite direction to the car's acceleration. However, due to buoyancy, the balloon is pushed "out of the way" by

2376-415: Is very small compared to most solids and liquids. For this reason, the weight of an object in air is approximately the same as its true weight in a vacuum. The buoyancy of air is neglected for most objects during a measurement in air because the error is usually insignificant (typically less than 0.1% except for objects of very low average density such as a balloon or light foam). A simplified explanation for

2464-460: The divisional , corps , or army level. American engineers built three types of floating bridges: M1938 infantry footbridges, M1938 ponton bridges, and M1940 treadway bridges, with numerous subvariants of each. These were designed to carry troops and vehicles of varying weight, using either an inflatable pneumatic ponton or a solid aluminum-alloy ponton bridge. Both types of bridges were supported by pontons (known today as "pontoons") fitted with

2552-490: The American Civil War various forms of pontoon bridges were tried and discarded. Wooden pontoons and India rubber bag pontoons shaped like a torpedo proved impractical until the development of cotton-canvas covered pontoons, which required more maintenance but were lightweight and easier to work with and transport. From 1864 a lightweight design known as Cumberland Pontoons , a folding boat system, were widely used during

2640-570: The Atlanta Campaign to transport soldiers and artillery across rivers in the South . In 1872 at a military review before Queen Victoria , a pontoon bridge was thrown across the River Thames at Windsor, Berkshire , where the river was 250 feet (76 m) wide. The bridge, comprising 15 pontoons held by 14 anchors, was completed in 22 minutes and then used to move five battalions of troops across

2728-646: The European Theater of Operations . The United States was the principal user, with Britain next. In the United States, combat engineers were responsible for bridge deployment and construction. These were formed principally into Engineer Combat Battalions , which had a wide range of duties beyond bridging, and specialized units, including Light Ponton Bridge Companies , Heavy Ponton Bridge Battalions , and Engineer Treadway Bridge Companies ; any of these could be organically attached to infantry units or directly at

Hangang Bridge - Misplaced Pages Continue

2816-599: The River Teme , close to their confluence. This allowed Cromwell to move his troops West of the Severn during the action on 3 September 1651 and was crucial to the victory by his New Model Army . The Spanish Army constructed a pontoon bridge at the Battle of Río Bueno in 1654. However, as the bridge broke apart it all ended in a sound defeat of the Spanish by local Mapuche-Huilliche forces. French general Jean Lannes 's troops built

2904-625: The Sava during the siege of Sirmium in 580 to completely surround the city with their troops and siege works. Emperor Heraclius crossed the Bosporus on horseback on a large pontoon bridge in 638. The army of the Umayyad Caliphate built a pontoon bridge over the Bosporus in 717 during the siege of Constantinople (717–718) . The Carolingian army of Charlemagne constructed a portable pontoon bridge of anchored boats bound together and used it to cross

2992-781: The Seine to seize Les Andelys from the English at the siege of Château Gaillard in 1203. During the Fifth Crusade , the Crusaders built two pontoon bridges across the Nile at the siege of Damietta (1218–1219) , including one supported by 38 boats. On 27 May 1234, Crusader troops crossed the river Ochtum in Germany on a pontoon bridge during the fight against the Stedingers . Imperial Mongol troops constructed

3080-402: The density of the fluid, V {\displaystyle V} represents the volume of the displaced fluid and g {\displaystyle g} is the acceleration due to gravity . Thus, among completely submerged objects with equal masses, objects with greater volume have greater buoyancy. Suppose a rock's weight is measured as 10 newtons when suspended by a string in

3168-502: The 1890s. It continued to be spelled in that fashion through World War II, when temporary floating bridges were used extensively throughout the European theatre . U.S. combat engineers commonly pronounced the word "ponton" rather than "pontoon" and U.S. military manuals spelled it using a single 'o'. The U.S. military differentiated between the bridge itself ("ponton") and the floats used to provide buoyancy ("pontoon"). The original word

3256-476: The British Army. Each pontoon was split into two halves, and the two pointed ends could be connected together in locations with tidal flow. Each half was enclosed, reducing the risk of swamping, and the sections bore multiple lashing points. The "Palsey pontoon" lasted until 1836 when it was replaced by the "Blanshard pontoon" which comprised tin cylinders 3 feet wide and 22 feet long, placed 11 feet apart, making

3344-753: The Danube during campaigns against the Avar Khaganate in the 790s. Charlemagne's army built two fortified pontoon bridges across the Elbe in 789 during a campaign against the Slavic Veleti . The German army of Otto the Great employed three pontoon bridges, made from pre-fabricated materials, to rapidly cross the Recknitz river at the Battle on the Raxa in 955 and win decisively against

3432-706: The Greek Mandrocles of Samos once engineered a 2-kilometre (1.2 mi) pontoon bridge that stretched across the Bosporus , linking Asia to Europe, so that Darius could pursue the fleeing Scythians as well as move his army into position in the Balkans to overwhelm Macedon . Other spectacular pontoon bridges were Xerxes' Pontoon Bridges across the Hellespont by Xerxes I in 480 BC to transport his huge army into Europe: and meanwhile other chief-constructors proceeded to make

3520-648: The Rhine during World War II , the Yom Kippur War , Operation Badr , the Iran–Iraq War 's Operation Dawn 8 , and most recently, in the 2022 Russian invasion of Ukraine , after crossings over the Dnipro River had been destroyed. A pontoon bridge is a collection of specialized, shallow draft boats or floats , connected together to cross a river or canal, with a track or deck attached on top. The water buoyancy supports

3608-660: The Slavic Obotrites . Tenth-Century German Ottonian capitularies demanded that royal fiscal estates maintain watertight, river-fordable wagons for purposes of war. The Danish Army of Cnut the Great completed a pontoon bridge across the Helge River during the Battle of Helgeå in 1026. Crusader forces constructed a pontoon bridge across the Orontes to expedite resupply during the siege of Antioch in December 1097. According to

Hangang Bridge - Misplaced Pages Continue

3696-563: The United States used cylinders split into three. In 1862 the Union forces commanded by Major General Ambrose Burnside were stuck on the wrong side of the Rappahannock River at the Battle of Fredericksburg for lack of the arrival of the pontoon train, resulting in severe losses. The report of this disaster resulted in Britain forming and training a Pontoon Troop of Engineers. During

3784-635: The Zhou people invented it and used it whenever they had occasion to do so, but the Qin people, to whom they handed it down, were the first to fasten it securely together (for permanent use). During the Eastern Han dynasty (25–220 AD), the Chinese created a very large pontoon bridge that spanned the width of the Yellow River . There was also the rebellion of Gongsun Shu in 33 AD, where a large pontoon bridge with fortified posts

3872-445: The air and will drift in the same direction as the car's acceleration. When an object is immersed in a liquid, the liquid exerts an upward force, which is known as the buoyant force, that is proportional to the weight of the displaced liquid. The sum force acting on the object, then, is equal to the difference between the weight of the object ('down' force) and the weight of displaced liquid ('up' force). Equilibrium, or neutral buoyancy,

3960-401: The area of the bottom surface. Similarly, the downward force on the cube is the pressure on the top surface integrated over its area. The surface is at constant depth, so the pressure is constant. Therefore, the integral of the pressure over the area of the horizontal top surface of the cube is the hydrostatic pressure at that depth multiplied by the area of the top surface. As this is a cube,

4048-484: The armored division. Stream-crossing equipment included utility powerboats, pneumatic floats, and two units of steel treadway bridge equipment, each of which allowed the engineers to build a floating bridge about 540 feet (160 m) in length. The United States Army Corps of Engineers designed a self-contained bridge transportation and erection system. The Brockway model B666 6 short tons (5.4 t) 6x6 truck chassis (also built under license by Corbitt and White )

4136-489: The boats, limiting the maximum load to the total and point buoyancy of the pontoons or boats. The supporting boats or floats can be open or closed, temporary or permanent in installation, and made of rubber, metal, wood, or concrete. The decking may be temporary or permanent, and constructed out of wood, modular metal, or asphalt or concrete over a metal frame. The spelling "ponton" in English dates from at least 1870. The use continued in references found in U.S. patents during

4224-449: The boats, singing as they walked, to give the armada a spectacular farewell. The late Roman writer Vegetius , in his work De Re Militari , wrote: But the most commodious invention is that of the small boats hollowed out of one piece of timber and very light both by their make and the quality of the wood. The army always has a number of these boats upon carriages, together with a sufficient quantity of planks and iron nails. Thus with

4312-411: The bridge they laid them above the stretched ropes, and having set them thus in order they again fastened them above. When this was done, they carried on brushwood, and having set the brushwood also in place, they carried on to it earth; and when they had stamped down the earth firmly, they built a barrier along on each side, so that the baggage-animals and horses might not be frightened by looking out over

4400-795: The bridge to be weighted down more heavily than the other parts. The roadway across the pontoons should be relatively light, so as not to limit the carrying capacity of the pontoons. The connection of the bridge to shore requires the design of approaches that are not too steep, protect the bank from erosion and provide for movements of the bridge during (tidal) changes of the water level. Floating bridges were historically constructed using wood. Pontoons were formed by simply lashing several barrels together, by rafts of timbers, or by using boats. Each bridge section consisted of one or more pontoons, which were maneuvered into position and then anchored underwater or on land. The pontoons were linked together using wooden stringers called balks . The balks were covered by

4488-592: The bridges; and thus they made them: They put together fifty-oared galleys and triremes, three hundred and sixty to be under the bridge towards the Euxine Sea, and three hundred and fourteen to be under the other, the vessels lying in the direction of the stream of the Hellespont (though crosswise in respect to the Pontus), to support the tension of the ropes. They placed them together thus, and let down very large anchors, those on

SECTION 50

#1732837500250

4576-409: The buoyant force is equal to the weight of the displaced fluid. The weight of the displaced fluid is directly proportional to the volume of the displaced fluid (if the surrounding fluid is of uniform density). The weight of the object in the fluid is reduced, because of the force acting on it, which is called upthrust. In simple terms, the principle states that the buoyant force (F b ) on an object

4664-565: The chronicles, the earliest floating bridge across the Dnieper was built in 1115. It was located near Vyshhorod , Kiev . Bohemian troops under the command of Frederick I, Holy Roman Emperor crossed the Adige in 1157 on a pontoon bridge built in advance by the people of Verona on orders of the German Emperor. The French Royal Army of King Philip II of France constructed a pontoon bridge across

4752-500: The city. Sassanid forces crossed the Euphrates on a quickly built pontoon bridge during the siege of Kallinikos in 542. The Ostrogothic Kingdom constructed a fortified bridge across the Tiber during the siege of Rome in 545 to block Byzantine general Belisarius ' relief flotillas to the city. The Avar Khaganate forced Syriac-Roman engineers to construct two pontoon bridges across

4840-661: The first secure and permanent ones (and linked with iron chains) in China came first during the Qin dynasty (221–207 BC). The later Song dynasty (960–1279 AD) Chinese statesman Cao Cheng once wrote of early pontoon bridges in China (spelling of Chinese in Wade-Giles format): The Chhun Chhiu Hou Chuan says that in the 58th year of the Zhou King Nan (257 BC), there was invented in the Qin State

4928-615: The floating bridge (fou chhiao) with which to cross rivers. But the Ta Ming ode in the Shih Ching (Book of Odes) says (of King Wen) that he 'joined boats and made of them a bridge' over the River Wei . Sun Yen comments that this shows that the boats were arranged in a row, like the beams (of a house) with boards laid (transversely) across them, which is just the same as the pontoon bridge of today. Tu Yu also thought this. ... Cheng Khang Chheng says that

5016-409: The floor of the fluid or rises to the surface and settles, Archimedes principle can be applied alone. For a floating object, only the submerged volume displaces water. For a sunken object, the entire volume displaces water, and there will be an additional force of reaction from the solid floor. In order for Archimedes' principle to be used alone, the object in question must be in equilibrium (the sum of

5104-407: The forces on the object must be zero), therefore; and therefore showing that the depth to which a floating object will sink, and the volume of fluid it will displace, is independent of the gravitational field regardless of geographic location. It can be the case that forces other than just buoyancy and gravity come into play. This is the case if the object is restrained or if the object sinks to

5192-433: The ground, the boats being fastened to this chain by means of big hooks. There were placed big wooden planks over the boats so firmly and evenly that all the animals were made to pass over it without difficulty. The Greek writer Herodotus in his Histories , records several pontoon bridges. Emperor Caligula built a 2-mile (3.2 km) bridge at Baiae in 37 AD. For Emperor Darius I The Great of Persia (522–485 BC),

5280-417: The help of cables to lash the boats together, a bridge is instantly constructed, which for the time has the solidity of a bridge of stone. The emperor Caligula is said to have ridden a horse across a pontoon bridge stretching two miles between Baiae and Puteoli while wearing the armour of Alexander the Great to mock a soothsayer who had claimed he had "no more chance of becoming emperor than of riding

5368-472: The integration of the pressure over the contact area may be stated as follows: Consider a cube immersed in a fluid with the upper surface horizontal. The sides are identical in area, and have the same depth distribution, therefore they also have the same pressure distribution, and consequently the same total force resulting from hydrostatic pressure, exerted perpendicular to the plane of the surface of each side. There are two pairs of opposing sides, therefore

SECTION 60

#1732837500250

5456-480: The narrower, lighter jeeps and trucks drove across the bridge with one wheel in the steel treadway and the other on the plywood. An Engineer Treadway Bridge Company consisted of company headquarters and two bridge platoons. It was an organic unit of the armored force, and normally was attached to an Armored Engineer Battalion. Each bridge platoon transported one unit of steel treadway bridge equipage for construction of ferries and bridges in river-crossing operations of

5544-467: The one side towards the Pontus because of the winds which blow from within outwards, and on the other side, towards the West and the Egean, because of the South-East and South Winds. They left also an opening for a passage through, so that any who wished might be able to sail into the Pontus with small vessels, and also from the Pontus outwards. Having thus done, they proceeded to stretch tight the ropes, straining them with wooden windlasses, not now appointing

5632-511: The original and cut it into two halves, was still in use with the British Army in 1924. The First World War saw developments on "trestles" to form the link between a river bank and the pontoon bridge. Some infantry bridges in WW1 used any material available, including petrol cans as flotation devices. The Kapok Assault Bridge for infantry was developed for the British Army, using kapok fibre -filled canvas float and timber foot walks. America created their own version. Folding Boat Equipment

5720-447: The original footbridge ( indogyo ) opened. It was damaged by a flood in July 1925. In October 1935 a second span was constructed, and tram tracks added. Shortly after the outbreak of the Korean War , South Korean troops bombed the bridge in an attempt to slow invading forces, as it was the river's solitary road crossing. The Hangang Bridge bombing killed between 500 and 1,000 people, mostly civilian refugees, who had not been informed of

5808-410: The outer force field is conservative, that is it can be written as the negative gradient of some scalar valued function: Then: Therefore, the shape of the open surface of a fluid equals the equipotential plane of the applied outer conservative force field. Let the z -axis point downward. In this case the field is gravity, so Φ = − ρ f gz where g is the gravitational acceleration, ρ f

5896-440: The plans to destroy the bridge. The bridge was not fully restored until 1954. In 1982 additional lanes were added, and it was renamed Hangang Bridge. [REDACTED] Media related to Hangang Bridge at Wikimedia Commons This article about a specific bridge or group of bridges in South Korea is a stub . You can help Misplaced Pages by expanding it . Pontoon bridge A pontoon bridge (or ponton bridge), also known as

5984-814: The pontoon very buoyant. The pontoon was tested with the Palsey pontoon on the Medway. An alternative proposed by Charles Pasley comprised two copper canoes, each 2 foot 8 inches wide and 22 foot long and coming in two sections which were fastened side by side to make a double canoe raft. Copper was used in preference to fast-corroding tin. Lashed at 10 foot centres, these were good for cavalry, infantry and light guns; lashed at 5 foot centres, heavy cannon could cross. The canoes could also be lashed together to form rafts. One cart pulled by two horse carried two half canoes and stores. A comparison of pontoons used by each nations army shows that almost all were open boats coming in one, two or even three pieces, mainly wood, some with canvas and rubber protection. Belgium used an iron boat;

6072-418: The pressure on the bottom being greater. This difference in pressure causes the upward buoyancy force. The buoyancy force exerted on a body can now be calculated easily, since the internal pressure of the fluid is known. The force exerted on the body can be calculated by integrating the stress tensor over the surface of the body which is in contact with the fluid: The surface integral can be transformed into

6160-502: The railroad was abandoned in 1961, when it was removed. The British Blanshard Pontoon stayed in British use until the late 1870s, when it was replaced by the " Blood Pontoon". The Blood Pontoon returned to the open boat system, which enabled use as boats when not needed as pontoons. Side carrying handles helped transportation. The new pontoon proved strong enough to support loaded elephants and siege guns as well as military traction engines . The British Blood Pontoon MkII, which took

6248-416: The resultant horizontal forces balance in both orthogonal directions, and the resultant force is zero. The upward force on the cube is the pressure on the bottom surface integrated over its area. The surface is at constant depth, so the pressure is constant. Therefore, the integral of the pressure over the area of the horizontal bottom surface of the cube is the hydrostatic pressure at that depth multiplied by

6336-548: The river. It was removed in 34 minutes the next day. At Prairie du Chien, Wisconsin , the Pile-Pontoon Railroad Bridge was constructed in 1874 over the Mississippi River to carry a railroad track connecting that city with Marquette, Iowa . Because the river level could vary by as much as 22 feet, the track was laid on an adjustable platform above the pontoons. This unique structure remained in use until

6424-594: The sea. According to John Hale's Lords of the Sea , to celebrate the onset of the Sicilian Expedition (415 - 413 B.C.), the Athenian general, Nicias , paid builders to engineer an extraordinary pontoon bridge composed of gilded and tapestried ships for a festival that drew Athenians and Ionians across the sea to the sanctuary of Apollo on Delos . On the occasion when Nicias was a sponsor, young Athenians paraded across

6512-409: The solid floor. An object which tends to float requires a tension restraint force T in order to remain fully submerged. An object which tends to sink will eventually have a normal force of constraint N exerted upon it by the solid floor. The constraint force can be tension in a spring scale measuring its weight in the fluid, and is how apparent weight is defined. If the object would otherwise float,

6600-494: The sum of the buoyancy force and the object's weight If the buoyancy of an (unrestrained and unpowered) object exceeds its weight, it tends to rise. An object whose weight exceeds its buoyancy tends to sink. Calculation of the upwards force on a submerged object during its accelerating period cannot be done by the Archimedes principle alone; it is necessary to consider dynamics of an object involving buoyancy. Once it fully sinks to

6688-643: The tension to restrain it fully submerged is: When a sinking object settles on the solid floor, it experiences a normal force of: Another possible formula for calculating buoyancy of an object is by finding the apparent weight of that particular object in the air (calculated in Newtons), and apparent weight of that object in the water (in Newtons). To find the force of buoyancy acting on the object when in air, using this particular information, this formula applies: The final result would be measured in Newtons. Air's density

6776-426: The top and bottom surfaces are identical in shape and area, and the pressure difference between the top and bottom of the cube is directly proportional to the depth difference, and the resultant force difference is exactly equal to the weight of the fluid that would occupy the volume of the cube in its absence. This means that the resultant upward force on the cube is equal to the weight of the fluid that would fit into

6864-417: The top face is directly proportional to the height (difference in depth of submersion). Multiplying the pressure difference by the area of a face gives a net force on the cuboid—the buoyancy—equaling in size the weight of the fluid displaced by the cuboid. By summing up sufficiently many arbitrarily small cuboids this reasoning may be extended to irregular shapes, and so, whatever the shape of the submerged body,

6952-403: The two kinds of rope to be used apart from one another, but assigning to each bridge two ropes of white flax and four of the papyrus ropes. The thickness and beauty of make was the same for both, but the flaxen ropes were heavier in proportion, and of this rope a cubit weighed one talent. When the passage was bridged over, they sawed up logs of wood, and making them equal in length to the breadth of

7040-413: The upward buoyant force that is exerted on a body immersed in a fluid , whether fully or partially, is equal to the weight of the fluid that the body displaces . Archimedes' principle is a law of physics fundamental to fluid mechanics . It was formulated by Archimedes of Syracuse . In On Floating Bodies , Archimedes suggested that (c. 246 BC): Any object, totally or partially immersed in

7128-399: The water than it is to pull it out of the water. For a fully submerged object, Archimedes' principle can be reformulated as follows: then inserted into the quotient of weights, which has been expanded by the mutual volume yields the formula below. The density of the immersed object relative to the density of the fluid can easily be calculated without measuring any volume is (This formula

7216-426: Was an organic unit of army and higher echelons. The M1940 could carry up to 25 short tons (23 t). The M1 Treadway Bridge could support up to 20 short tons (18 t). The roadway, made of steel, could carry up to 50 short tons (45 t), while the center section made of 4 inches (100 mm) thick plywood could carry up to 30 short tons (27 t). The wider, heavier tanks used the outside steel treadway while

7304-656: Was constructed across the Yangtze River , eventually broken through with ramming ships by official Han troops under Commander Cen Peng. During the late Eastern Han into the Three Kingdoms period, during the Battle of Chibi in 208 AD, the Prime Minister Cao Cao once linked the majority of his fleet together with iron chains, which proved to be a fatal mistake once he was thwarted with a fire attack by Sun Quan 's fleet. The armies of Emperor Taizu of Song had

7392-505: Was derived from Old French ponton , from Latin ponto ("ferryboat"), from pons ("bridge"). When designing a pontoon bridge, the civil engineer must take into consideration Archimedes' principle : Each pontoon can support a load equal to the mass of the water that it displaces . This load includes the mass of the bridge and the pontoon itself. If the maximum load of a bridge section is exceeded, one or more pontoons become submerged. Flexible connections have to allow for one section of

7480-566: Was developed in 1928 and went through several versions until it was used in WW2 to complement the Bailey Pontoon . It had a continuous canvas hinge and could fold flat for storage and transportation. When assembled it could carry 15 men and with two boats and some additional toppings it could transport a 3-ton truck. Further upgrades during WW2 resulted in it moving to a Class 9 bridge. Pontoon bridges were used extensively during World War II, mainly in

7568-417: Was suitable for all normal infantry division loads without reinforcement, greater with. A Heavy Ponton Bridge Battalion was provided with equipage required to provide stream crossing for heavy military vehicles that could not be supported by a light ponton bridge. The Battalion had two lettered companies of two bridge platoons each. Each platoon was equipped with one unit of heavy ponton equipage. The battalion

7656-489: Was the first to create a pontoon bridge in the 11th century BC. However, the historian Joseph Needham has pointed out that in all likely scenarios, the temporary pontoon bridge was invented during the 9th or 8th century BC in China, as this part was perhaps a later addition to the book (considering how the book had been edited up until the Han dynasty , 202 BC – 220 AD). Although earlier temporary pontoon bridges had been made in China,

7744-490: Was used to transport both the bridge's steel and rubber components. A single Brockway truck could carry material for 30 feet (9.1 m) of bridge, including two pontons, two steel saddles that were attached to the pontons, and four treadway sections. Each treadway was 15 feet (4.6 m) long with high guardrails on either side of the 2 feet (0.61 m) wide track. Archimedes%27 principle Archimedes' principle (also spelled Archimedes's principle ) states that

#249750