Historical evolution
The ancient period
The first vaults were made with horizontal stones, arranged flying over each other, an arrangement known as "corbel." At Abydos, in the palace of Ozymandias, whose reign dates back to around 2500 BC. C., a vault of this type has been found.[D 1] The same arrangement is found in Thebes "Thebes (Egypt)"), in the temple of Amun-Ra").[D 2] However, the most beautiful vault of this type is probably that of the Treasury of Atreus,[D 3] an impressive tomb of tholos located in Mycenae, in Greece, and built around 1250 BC. It consists of a room semi-subterranean circular with an ogival section cover. With an interior height of and a diameter of ,[7] it was the largest and widest dome in the world for more than a millennium, until the construction of the Baths of Mercury") in Bayas "Bayas (Italy)") and the Pantheon in Rome.[D 2].
Three ancient bridges remain in the Argolis, in the Peloponnese, including the Mycenaean Kazarma Bridge, built according to the technique of false arch vaults or corbel arches, with the help of a stack of roughly hewn stones.
These bridges were probably built around 1300 BC. C., in the Mycenaean period (Bronze Age) and, more specifically, of the Helladic IIIb (approx. 1340/1200 BC), for the road that connected the main cities of Mycenae, Argos "Argos (Greece)") and Tiryns, in the port of Palea Epidauros").
Vaults with convergent joints, that is, those in which the joints are perpendicular to the surface of the intrados, typical of masonry bridges, already existed in fact in several monuments of ancient Egypt. In Nubia, in one of the pyramids of Meroe, there is a true barrel vault composed of regularly paired voussoirs.[D 4] In Gebel Barkal, two porticos that give access to the pyramids are covered, one by a pointed vault and the other by a barrel vault, both executed with voussoirs with converging joints. In the tomb of Amenhotep I, and, therefore, dated about eighteen centuries before Christ,[D 4] you can see an elliptical barrel vault, made of brick.
More recent, in Europe, they can be found on the walls of the Etruscan city of Volterra, dating from the century or century BC. C. The Porta all'Arco takes up the same principle of the construction of an arch.
The Roman period
The recovery of the vault technique, its development and perfection and its use throughout Europe for the construction of bridges are due to the Romans. Such a vast empire meant a reliable road network, practicable in all seasons and equipped with more solid constructions than simple wooden bridges.[8].
It is assumed that the oldest Roman vaulted work is a sewer known as the Cloaca Maxima executed during the reign of Tarquin the Elder, whose construction began about 600 years before Christ.[D 5].
Roman bridges are strong and arched, that is, with semicircular arch-shaped vaults, which rest on thick pylons, with a width approximately equal to half the span of the vault.[9].
The Aemilius Bridge, now the Rotto Bridge, is the oldest stone bridge in Rome.[10] It was built by Marcus Aemilius Lepidus "Marcus Aemilius Lepidus (consul 187 BC)") in 179 BC. C. It was restored several times, the last in 1575 by Gregory "Tympanum (bridge) (not yet written)").[D 6] Only a single arch remains.
One of the first achievements of the Roman road network is the Milvian Bridge,[12] built over the Tiber River by the consul Marcus Aemilius Scaurus in 115 BC. C.. Located about 3 km from Rome, where the Via Flaminia and Via Cassia meet to cross the river, it was the obligatory access to Rome for all travelers coming from the north. Due to its strategic position, the Milvian Bridge was the scene of many battles. There, in the year 312, Emperor Constantine I "Constantine I (Emperor)") defeated his rival Maxentius in a battle that is still known as the Battle of Milvian Bridge.[13]
There are many bridges built in the Italian provinces, all notable for their differences. Among them the bridge of Pont-Saint-Martin&action=edit&redlink=1 "Bridge of Pont-Saint-Martin (Italy) (not yet written)"), built over the Lys between the years 70 to 40 BC. C. at the entrance to the Aosta Valley. The only light bow and arrow was far surpassed for the time. The structure presents two different manufacturing techniques: the lower part is made of gneiss blocks, received dry, while the upper part is a superposition of strata consisting of fragments of gneiss and limestone, interspersed with stone bands.[14][P2 1].
The Fabrizio Bridge is, in turn, the only ancient bridge in Rome, completely preserved. Built in the year 62 BC. C. by the Viarum curator Lucio Fabricio, connects the Tiber Island to the shore of the Champ de Mars, near the Theater of Marcellus, and the Boarium Forum.[15][P2 2].
The Ponte Sant'Angelo is another ancient bridge in Rome that connects the two banks of the Tiber, in front of the Castel Sant'Angelo. It was built in the year 134 during the reign of Emperor Hadrian, who gave it its name Pons Ælius.[16][17][P2 3].
In Spain and Portugal you can see the most spectacular Roman works, mostly built in the Augustinian era.[P2 4] The Mérida Bridge "Roman Bridge (Mérida)") in Extremadura, is a long bridge, composed of 60 arches that crossed the Guadiana River.[P2 5] The Alcántara Bridge,[18] built on the Tagus River in the years 103 and 104 d. C.,[19] it has six semicircular arches with spans from to , resting on thick square pylons, some of which, those located in the river, reach a height of almost 40 meters above the foundations. Beauty results from the imposing dimensions, the simplicity of the forms and the appearance of solidity.[P2 6]
Two imposing aqueduct bridges from this period, built under Trajan's command between the years 98 and 117, are also notable: the Segovia aqueduct, with 128 arches in length;[P2 7] and the Ferreres aqueduct (Tarragona), with a length that crosses the Francolí valley.[P2 7].
In the 19th century, lowered arch bridges or voussoir bridges appeared. The Limira Bridge,[20] located near Limira in Lycia, a region today in Türkiye, is one of the first representatives in the world. The bridge is long and has 26 segmental arches and two semicircular ones.[21].
In France, the Pont du Gard is a Roman aqueduct bridge on three levels, with a height of at the highest point, located in the commune of Vers-Pont-du-Gard, near Remoulins, in the Gard department. It extends over the Gardon River and was probably built in the first half of the century, ensuring the continuity of the Roman aqueduct that carried water from Uzès to Nîmes and which had a length of .[P2 8].
In Asia, it is almost certain that the Chinese invented the vault before or after the Greeks and that they built vaulted bridges very early, perhaps before the Romans.[P3 1] According to Chinese archaeologists, the oldest bridge would be the Lurenqiao Bridge, built around 282 BC. C., near the ancient palace of Luoyang (Henan province).[22].
The Zhaozhou Bridge,[23] which resembles Western bridges of the 19th century, was built around the year 605.[23] It is the oldest open spandrel and voussoir-vaulted factory bridge in the world.[24] It is also the oldest bridge in China, still in service. It is located in the Zhao district of the city-prefecture of Shijiazhuang, in Hebei province.[25] The span of the arch is .[22][26].
Another notable ancient bridge is the Baodaiqiao Bridge, built over the Grand Canal in Suzhou by Wang Zhongshu, governor of Suzhou under the Tang Dynasty (618-907). With a length of , it has 53 arches, making it the bridge in China with the largest number of arches.[26].
The medieval period
After the fall of the Roman Empire, a period of almost 500 years follows, a little less than half of the millennium, occupied by the Middle Ages, of which not the slightest achievement remains in terms of engineering works.[27] The bridges were at that time built of wood.
Starting in the 19th century, many works of varied and heavy shapes will be built. These works are made up of arches that are often very unequal, whose vaults are slightly lowered, semicircular or pointed arches, since the latter shape allowed the pressure on the supports to be reduced; They rest on thick pylons with very protruding ends, at least upstream. The useful widths between the walls were small and the passage almost always had access ramps with very steep slopes. the Saint-Bénézet bridge,[28] in Avignon, over the Rhône river (1177-1187);[28] the old bridge of Carcassonne,[29] on the Aude river (1180);[29] the Petit-Pont[30] in Paris, over the Seine river (1174-1186);[30] the Valentré bridge,[31] at Cahors, on the river Lot (1231); the Saint-Martial bridge&action=edit&redlink=1 "Saint-Martial Bridge (Limoges) (not yet written)")[32] of Limoges, over the river Vienne (1215);[32][9] the bridge of Entraigues") over the river Lot; and the bridge of the Truyère") (beginning of the century).
From the century onwards, the bridges became more stylized, refining both the thickness of the pylons and the edge of the arches by improving the empirical relationships (see the Devil's Bridge "Devil's Bridge (Martorell)") in Martorell, from 1282). It will be possible to overcome lights around the, until then inconceivable: bridge of San Martín "Bridge of San Martín (Toledo)") that spans the Tagus River in Toledo (Spain), Castelvecchio bridge in Verona (Italy) ( ) and in France, the bridge of Nyons (), the Céret "Devil's Bridge (Céret)") () over the river Tech (1366) and the bridge of Vieille-Brioude over the river Allier (19th century) which had a single light arch, now disappeared, but which was for four centuries the largest existing stone vault.
The Middle Ages were also characterized by the construction of numerous wooden bridges, often crowned by buildings in which shops were set up, which constituted the type of inhabited bridge. One of the most famous is the Ponte Vecchio on the Arno River, in the city of Florence, in Italy. First built in wood, it was rebuilt in stone in 1345 by Taddeo Gaddi or Neri di Fioravante, according to sources, but the famous gallery erected above the shops will not be built until the 2nd century.[P2 9].
The Marco Polo Bridge is probably the first Chinese bridge known in the West through the stories of the Venetian traveler Marco Polo on his journey to China in the 19th century. It is located about Peking (Peking) and was completed in 1192. With a width of and length, it has 11 arches of different sizes, the largest having a span of .[P3 2].
The Chinese vaulted bridges reach the peak of their splendor in Fujian, with very thin arches. The Xiao Bridge built in 1470 has a clear height of with an arch thickness of only , half of a normal arch.[33] It is still in service and supports current traffic. Another notable bridge from this period is the Gao-po bridge, located in Yongding") and built in 1477. Its span is 20 meters and the arch is only thick, without any type of connecting mortar.[33].
From the Renaissance to the end of the 17th century
In the West, between the 19th century, the architects of famous bridges in Florence, Venice and other Italian cities were inspired by regular forms borrowed from the past, but their tendency to be more artists than builders sometimes led them to abuse the superstructure and other decorations. The two most significant examples are the Ponte Vecchio in Florence and the Rialto Bridge[34] on the Grand Canal in Venice.[35].
The bridge becomes a central element of large urban planning projects. In France, the first renowned architects appear, such as Androuet du Cerceau, to whom we owe the Pont Neuf[36] in Paris, which began in 1578 and was not completed until 1604 due to the religious wars.[37] It facilitates the passage between the Louvre Palace and the Abbey of Saint-Germain-des-Prés, next to the monument erected in honor of Henry IV located at the downstream end of the île de la Cité and is the bridge is the oldest service in Paris. It was at that time the bridge that introduced the carpanel arch, a curve with three or more centers, which never replaced the semicircular curve.
In Central Europe, the Stari Most in Mostar is a bridge built in 1565 by the architect Mimar Hajrudin, a student of the Ottoman architect Sinan. It connects the two parts of this city in Bosnia and Herzegovina, on the Neretva River. The bridge consists of a single steep arch, spanning, width and length. The architecture of this bridge, the mounting of the bridge, the technique used at the time of its construction, is surprising, giving it great solidity. It was such that it has stood for centuries in all conflicts except the last.
The Khaju Bridge, in the city of Isfahan, is an extraordinary bridge in Iran. Built around 1667, it has 18 pointed arch vaults, and supports a () pathway and has shaded covered side corridors. It is also flanked by two central pavilions and watchtowers. Combining architecture and art in wonderful functional harmony, this beautiful bridge also serves as a dam and spillway, as it has gates between its arches.[24].
18th century
Until the century, bridges were built by transposition of time-tested construction techniques, but not as a result of a theoretical approach. The formulas used, derived from observation and practice, were numerous. The thickness of the key "Key (architecture)"), of the kidney, of the pylons or pillars, was simply deduced from the span or opening of the bridge.
Philippe de La Hire in 1695,[M 1] and then in 1712[M 1][38] attempted a first approximation in the calculation of vaults, a calculation that consisted of verifying, a posteriori, that the designed vault had some possibility of being stable, and that the materials that constituted it did not collapse under the loads.[39] He could not obtain sufficient results for practice, but he had the merit of pointing out highlighted two concepts that, a century later, would prove to be very fruitful:[P 1][M 1].
Jean-Rodolphe Perronet, first director of the École nationale des ponts et chaussées[40]) and illustrious builder, determined in 1777 the first rules for calculating the thickness of the vaults and piédroits (foot of the arch). Couplet introduced the notion of lines of center of pressure and the concept of block rotation failure. The works of Charles de Coulomb, published in 1773, introduced a mechanism of ruin by sliding along a joint and resumed, forty-three years later, the mechanism of failure by rotation of blocks.[41] However, until the century these theories did not have practical applications.
Although the bridges of the Middle Ages had been somewhat sufficient until then, they were works that had been repaired several times and had narrow roads that were no longer suitable for the new commercial exchanges. The century will see important activity in the construction of bridges in Europe, especially in France.[42].
An evolution also occurred in this period. During the first half of the century, the bridges were on the back of a donkey or with a very pronounced escarpment and composed of decreasing arches, from the middle of the banks, such as the Jacques-Gabriel bridge in Blois, while from 1750 the slopes will be less pronounced and with arches of equal length (Wilson bridge of Tours&action=edit&redlink=1 "Wilson Bridge (Tours) (not yet written)") crossing the Loire, with a total length of 434 m).
The central region "Centre (France)") of France (Seine and Loire basins) has been particularly privileged. It saw the birth, among other things, of the pont Royal&action=edit&redlink=1 "Pont Royal (Paris) (not yet written)") in Paris, which, although built from 1685 to 1687 by Jules Hardouin-Mansart, announced, by its structure, the great bridges of the following century; the Blois bridge, built between 1716 and 1724 by Jacques V Gabriel") and Robert Pitrou"); and the George-V bridge") over the Loire in Orléans, from 1751 to 1760 by Jean Hupeau") and Robert Soyer") (325 m); the Moulins bridge over the Allier, from 1756 to 1770 by Louis de Règemorte") (301.50 m); the Saumur bridge, from 1756 to 1768, by Jean-Baptiste de Voglie") (276 m); the Neuilly bridge"), from 1766 to 1769; the Concorde Bridge") in Paris, from 1787 to 1791, masterpieces by Perronet").
19th century
At the beginning of the century, architects and engineers had acquired extensive experience in the construction of stone and wooden bridges. In 1810, Louis-Charles Boistard") shows, after many tests, that the breakage of arches is produced by the rotation of four blocks.[43] Henri Navier, in his lectures at the École des Ponts et Chaussées (1825), introduced the concept of elasticity of materials and defined the "rule of the central third", a limit in which the line of pressure centers of the vault must be limited.[41].
These results allowed E. Mery to publish in 1840 a method of verifying vaults that was used throughout the century and still sometimes today. [l'intrados et l'extrados form deux limits dont la courbe des pressions ne doit never sortir et lorsque cela arrive, l'équilibre est impossible]. This method is described in the Construction de ponts course by Croisette-Desnoyers, in 1885, and in what remains of the masterful work consecrating the end of the construction of factory bridges, the Grandes voûtes [Grandes voûtes], by Paul Séjourné, published in 1913.[45].
In 1867, Durand-Claye improved this method, but his proposal was not successful, since it required laborious calculations.[44][M 3].
In the field of materials, progress will come from the binders used in the manufacture of mortars used in the arch voussoirs. The Frenchman Louis Vicat discovered in 1817 the principle of the hydraulicity of lime, which concerns the proportion of clay and the firing temperature, and published his work without having a patent. In 1824, the British Joseph Aspdin applied for a patent for the manufacture of a quick-setting hydraulic lime that he commercially called Portland cement. But the great advance came in 1840 with the discovery, also by Vicat, of the principles of slow hydraulic cements (now known as Portland cements). The mortars used to receive the voussoirs would be a significant progress in terms of the resistance of the vaults.
Regarding the construction technique, Paul Séjourné updated the taste for the construction of the arch using successive rollers, a technique already used by the Romans and in the Middle Ages, but fallen into disuse, and the use of radiating forms and rolled forms, by steel cable stays. This allowed a saving of between 20 and 70% of the wood used and reduced construction time.[46] Furthermore, inspired by the past, he systematically highlighted the vaults with archivolts, highlighting the elegance of their form.[47].
In 1870, Jules Dupuit was the first to propose articulating the arches, which made it easier to make the materials work since the stresses that required them were better known.[48].
The development of railways in the 19th century led to the appearance of large factory viaducts. In fact, the design of the railway tracks could not be adapted to the relief of the crossed regions due to the low admissible slopes, less than 10 mm per meter at the beginning, and the large radii of curvature necessary for the stability of the vehicles. The importance of the slopes was limited by the lack of grip of the locomotives, their low power and the insufficiency of their braking means.[P 2].
20th century
An important innovation will come from the conception of the vault. To allow for greater spans, the increase in pressure due to modern mortars and the reduction in thickness had reached its limits. Paul Séjourné had the idea of unfolding the vault into two parallel arches. Although this principle of duplication had already been used in the past in small vaults such as the Pont du Gard or the Pont Saint-Bénézet, it is up to Paul Séjourné to understand its full importance in terms of the performance of materials and economy and to carry out the first, thanks to the coupling with a reinforced concrete deck, one of the greatest works of the century: the Adoldo Bridge) in Luxembourg (1899-1903). light made until the moment of its inauguration.[49] The principle will be repeated several times in several countries, especially in the United States, but also in France with the very delicate bridge of the Catalans") in Toulouse (1904-1907).[50].
The Plauen Bridge"), in Plauen, over the Weisse River"), surpassed it in 1905 with a span of .[51] This work is the last factory vaulted bridge built in the West. With the unfolding of the arch, Paul Séjourné paved the way for the construction of large arch bridges in reinforced concrete. The advent of new steel construction techniques, such as suspension bridges, prestressed concrete bridges, or cable-stayed bridges, suddenly sounded the end of factory bridge construction in the West.
While in the West the technique was definitively abandoned in favor of standard reinforced concrete bridges, for small spans, and other types for large spans, in China many factory bridges were built in the century, particularly in the 1960s and 1970s. Thus, in the province of Fujian, 1,152 bridges of this type were built in two decades, 60% of all bridges built during that period.[52].
At the same time the records of the great lights were surpassed. In 1965, the threshold of 100 m was crossed with the Hongdu Bridge, in Guangxi Province. factory bridge was reached in July 2000 with the Dähne Bridge on the Jin-Jiao Highway in Shanxi Province, with a length of .[56][57].