Building Name – Eiffel Tower
Location – Paris, France
Architects – Gustave Eiffel
Engineers – Maurice Koechlin & Emile Nouguier
Contractor – Gustave Eiffel & Cie
Architect – Stephen Suavestre
Year of Start – 28 January 1887
Year of End – 1889
- The Exposition Universelle of 1889, also known as the World’s Fair, was held in Paris celebrating 100 years since the start of French Revolution.
- Paris used this celebration to reconstruct parts of the city surrounding the Bastille. There were attractions, exhibits, 28,000,000 visitors, and most unforgettable of all, the 1063-foot breathtaking iron structure so famously known as the Eiffel Tower.
- The tower is 324 metres (1,063 ft) tall, about the same height as an 81-storey building, and the tallest structure in Paris.
- Its base is square, measuring 125 metres (410 ft) on each side. During its construction, the Eiffel Tower surpassed the Washington Monument to become the tallest man-made structure in the world, a title it held for 41 years until the Chrysler Building in New York City was finished in 1930.
- Due to the addition of a broadcasting aerial at the top of the tower in 1957, it is now taller than the Chrysler Building by 5.2 metres (17 ft). Excluding transmitters, the Eiffel Tower is the second-tallest structure in France after the Millau Viaduct.
- The tower has three levels for visitors, with restaurants on the first and second levels.
- The top level’s upper platform is 276 m (906 ft) above the ground – the highest observation deck accessible to the public in the European Union.
- Tickets can be purchased to ascend by stairs or lift (elevator) to the first and second levels. The climb from ground level to the first level is over 300 steps, as is the climb from the first level to the second. Although there is a staircase to the top level, it is usually only accessible by lift.
- Emile Nouguier and Maurice Koechlin, the two chief engineers in Eiffel’s company, had the idea for a very tall tower in June 1884.
- It was to be designed like a large pylon with four columns of lattice work girders, separated at the base and coming together at the top, and joined to each other by more metal girders at regular intervals.
- The company had by this time mastered perfectly the principle of building bridge supports. The tower project was a bold extension of this principle up to a height of 300 metres – equivalent to the symbolic figure of 1000 feet.
- On September 18 1884 Eiffel registered a patent “for a new configuration allowing the construction of metal supports and pylons capable of exceeding a height of 300 metres.
- In order to make the project more acceptable to public opinion, they commissioned the architect Stephen Sauvestre to work on the project’s appearance.
- For the east and south legs were straightforward, with each leg resting on four 2 m (6.6 ft) concrete slabs, one for each of the principal girders of each leg. The west and north legs, being closer to the river Seine, were more complicated.
- Each slab needed two piles installed by using compressed-air caissons 15 m (49 ft) long and 6 m (20 ft) in diameter driven to a depth of 22 m (72 ft) to support the concrete slabs, which were 6 m (20 ft) thick. Each of these slabs supported a block of limestone with an inclined top to bear a supporting shoe for the ironwork.
- Each shoe was anchored to the stonework by a pair of bolts 10 cm (4 in) in diameter and 7.5 m (25 ft) long. The foundations were completed on 30 June, and the erection of the ironwork began.
- The drawing office produced 1,700 general drawings and 3,629 detailed drawings of the 18,038 different parts needed.
- All the elements were prepared in Eiffel’s factory located at Levallois-Perret on the outskirts of Paris.
- In all, 18,038 pieces were joined together using 2.5 million rivets.
- At first the legs were constructed as cantilevers, but about halfway to the first level, construction was paused in order to create a substantial timber scaffold.
- At this stage, a small “creeper” crane designed to move up the tower was installed in each leg. They made use of the guides for the lifts which were to be fitted in the four legs. The critical stage of joining the legs at the first level was completed by the end of March 1888.
- Hydraulic jacks were fitted to the shoes at the base of each leg, capable of exerting a force of 800 tonnes, and the legs were intentionally constructed at a slightly steeper angle than necessary, being supported by sandboxes on the scaffold.
- Construction involved 300 on-site employees.
- Constructing lifts to reach the first level was relatively straightforward: the legs were wide enough at the bottom and so nearly straight that they could contain a straight track, and a contract was given to the French company Roux, Combaluzier & Lepape for two lifts to be fitted in the east and west legs.
- Installing lifts to the second level was more of a challenge because a straight track was impossible.
- The European branch of Otis Brothers & Company submitted a proposal.
- The car was divided into two superimposed compartments, each holding 25 passengers, with the lift operator occupying an exterior platform on the first level.
- Motive power was provided by an inclined hydraulic ram 12.67 m (41 ft 7 in) long and 96.5 cm (38.0 in) in diameter in the tower leg with a stroke of 10.83 m (35 ft 6 in): this moved a carriage carrying six sheaves.
- Five fixed sheaves were mounted higher up the leg, producing an arrangement similar to a block and tackle but acting in reverse, multiplying the stroke of the piston rather than the force generated.
- The hydraulic pressure in the driving cylinder was produced by a large open reservoir on the second level. After being exhausted from the cylinder, the water was pumped back up to the reservoir by two pumps in the machinery room at the base of the south leg. This reservoir also provided power to the lifts to the first level.
- A pair of 81 m (266 ft) hydraulic rams were mounted on the second level, reaching nearly halfway up to the third level.
- One lift car was mounted on top of these rams: cables ran from the top of this car up to sheaves on the third level and back down to a second car.
- Each car only travelled half the distance between the second and third levels and passengers were required to change lifts halfway by means of a short gangway. The 10-ton cars each held 65 passengers.
- After dark, the tower was lit by hundreds of gas lamps, and a beacon sent out three beams of red, white and blue light.
- Eiffel had a permit for the tower to stand for 20 years but as the tower proved to be valuable for communication purposes, it was allowed to remain after the expiry of the permit.
- Eiffel made use of his apartment at the top of the tower to carry out meteorological observations, and also used the tower to perform experiments on the action of air resistance on falling bodies.