Orly airship hangars

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The Orly airship hangars in the French commune of Orly, south of Paris, were two airship hangars designed by Eugène Freyssinet made of parabolic barrel shells formed by staggered reinforced concrete arches . Orly's airship hangars are considered a milestone in the history of concrete construction.

prehistory

Freyssinet had offered the French military various designs of aircraft hangars made of wide reinforced concrete arches as early as 1913, but these were initially not pursued because of the First World War . It was not until the winter of 1915–1916 that they came back and had 8 hangars with a length of 60 m and a span of 46 m built on the Avord airfield east of Bourges , today's Base aérienne 702 Avord . This was followed by 31 somewhat shorter hangars in Istres and in 1919 a hangar in Villacoublay with an area of ​​120 × 45 m without pillars.

History and description

planning

The tender for the airship hangars at Orly airfield provided for two 300 m long hangars through which a sphere with a diameter of 50 meters could be maneuvered continuously. According to Freyssinet's plans, a parabolic arch construction proved to be suitable for this, which, in addition, could offer enough resistance to lateral winds due to its huge dimensions.

In his deliberations, Freyssinet assumed that a double parabolic shell with short vertical spacer bars between the shells would theoretically be the ideal shape from a static point of view, but could not be manufactured at reasonable cost in practice. It would be conceivable to break up the shells into inner and outer strip-shaped belts that alternate and are connected by the webs. The vertical surfaces of the webs would make the formwork more difficult. If narrower straps connected by inclined webs were used, the result would be a shape - similar to the Zoresis iron that was widespread at the time or today's trapezoidal sheet - that could be produced using just two formworks, whereby the formworks could easily be lifted off the hardened concrete. For structural reasons, the outer belt strips had to be stiffened with horizontal steel bars that ran at different heights from one end of the hall to the other.

description

As a result, according to Freyssinet's plans, two halls with a length of 300 m, a width of 91 m and a height of 59.30 m were created. Each hall was subdivided into 40 individual arches made of reinforced concrete, consisting of a profile, which were constantly 7.50 m wide. The profiles had a construction height of 5.40 m at the bottom and 3.00 m at the top of the arch. The inner belt of the profile had a thickness of 34 cm at the base, which decreased to 20 cm at the apex. The thickness of the inclined webs was initially 15.5 cm and was reduced to 9 cm at the top.

Between the individual arches, a 1.24 m wide window was installed in the lower area, from a height of 20 m window strips made of specially reinforced yellow glass were installed to allow light into the hall on the one hand and to protect the airships from strong sunlight on the other . Small reinforced concrete roof turrets were inserted at the apex for ventilation. In order to be able to inspect and maintain the top of the airships, five narrow catwalks were hung inside under the roof, on which gondolas with loads of up to 2 tons could be moved.

Each hall stood on two 1 m thick and 7.50 m wide strip foundations made of reinforced concrete, the upper edge of which was 2 m below the surface of the site. With these foundations, it was possible to comply with the requirement that the soil pressure on the sandy clay soil had to remain below 1.5 kg / cm².

construction

The halls were built between 1922 and 1924 within the contractual construction period of two years by Entreprises Limousin (Procédés Freyssinet) under the direction of their technical director Freyssinet. Large steel gates were not part of the order; they were to be built later on the basis of a separate tender. The administration and operations buildings added later were also not part of the original scope of the order.

Freyssinet endeavored to divide the construction process into series of constant work processes in which as few formwork as possible could be used again and again. For this purpose, he developed devices with which the formwork of the arches could be moved on rails, brought into the correct position, filled with reinforcement and concrete, lifted off after the concrete had set and moved 7.50 m sideways to the position of the next arch. The formwork forms themselves were made from pine planks, which were cleaned and oiled after each use and prepared for the next use.

First of all, the bottom 3 m of the arched profiles were concreted on the foundations - on both sides of a hall and at the same time for both halls. In a second round, the profiles were increased to 17 m. Depending on the weather, the outer formwork was removed after the concrete had hardened from 2 to 5 days. The actual arches were concreted on these 17 m high profiles. The falsework consisted of two arched legs, each weighing 45 t, which were erected on the movable supports, and a 30-tonne middle section that was pulled up from the arched legs and fastened. The entire arch was tensioned, stabilized and adjusted with an ingenious network of cables and straps so that its correct shape was secured during the concreting process. A mixture of 350 kilograms of cement per 1 m³ of sand and gravel was used for the concrete . After the concrete had set, the entire arch could be lowered. Initially, in the cold winter weather, the production of one of these arches above 17 m in height took 12 days, with increasing routine and better weather the cycle sank to five to six days. The arches in both halls were produced in a total of 44 weeks.

The halls were destroyed by American air forces during World War II in 1944.

literature

  • The hangars à dirigeables à l'Aéro-port d'Orly. In: L'Aéronautique. N ° 45, Paris, February 1923, pp. 74-78 ( digitized on BnF Gallica).
  • Eugène Freyssinet: Hangars à dirigeables en ciment armé en construction à l'aéroport de Villeneuve-Orly (Seine-et-Oise).
    In: Le Génie Civil. ,
    • N ° 2145 of September 22, 1923, pp. 265-273. ( Digitized on BnF Gallica)
    • N ° 2146 of September 29, 1923, pp. 291-297. ( Digitized on BnF Gallica)
    • N ° 2147 of October 6, 1923, pp. 313-319. ( Digitized on BnF Gallica)
  • PEM: Airship hangars made of reinforced concrete in Villeneuve-Orly. In: Schweizerische Bauzeitung . Half volume 82, No. 12, September 22, 1923, p. 154 f. ( Digitized on ETH - e-periodica)
  • Eugène Freyssinet: Les hangars à dirigeables de l'aeroport d'Orly. In: Bulletin Technique de la Suisse Romande. N ° 22, November 2, 1929, pp. 255-257. (after a lecture at an event of the Société suisse des ingénieurs et des architectes in Lausanne from October 8th to 12th 1929) ( digitized on ETH - e-periodica)
  • Günter Günschel: Great designers. Volume 1: Freyssinet - Maillart - Dischinger - Finsterwalder. (= Bauwelt Foundations. ISSN  0522-5094 , Volume 17). Ullstein, Berlin 1966, pp. 49-51, pp. 57-65.

Web links

Individual evidence

  1. ↑ a b Entry No. IA00089815 in the Base Mérimée of the French Ministry of Culture (French)
  2. ^ Eugène Freyssinet: Hangars à dirigeables en ciment armé ... In: Le Génie Civil, 1923, p. 266.
  3. ↑ Le hangar "Freyssinet" in Avord; on hangars d'aérodromes
  4. ↑ The coordinates were taken from: Page Paris- (Villeneuve-Orly) In: Internationalesflugandbuch: Flug-Atlas 1931. edited by Digitale Luftfahrt-Bibliothek
  5. ^ A b Eugène Freyssinet: Les hangars à dirigeables de l'aeroport d'Orly. In: Bulletin Technique de la Suisse Romande. N ° 22, November 2, 1929, pp. 255-257 ( digitized from ETH - e-periodica).
  6. ↑ a b c Les hangars à dirigeables à l'Aéro-port d'Orly. In: L'Aéronautique , N ° 45, Paris, February 1923, p. 74.
  7. ^ Advertisement by the Société Anonyme des Entreprises Limousin (procédés Freyssinet). In: L'Aéronautique N ° 68, Paris, January 1925, (digital p. 13/91)
  8. ↑ Freyssinet later stated external dimensions of 300 × 92 × 58 m ( Les hangars à dirigeables de l'aeroport d'Orly. In: Bulletin Technique de la Suisse Romande. N ° 22, November 2, 1929, p. 255)
  9. ↑ In the article Airship halls made of reinforced concrete in Villeneuve-Orly in Schweizerische Bauzeitung , September 1923, a length of 300 m, a span of 91 m and a clearance height of 59 m are given.
  10. ↑ a b c d Eugène Freyssinet: Hangars à dirigeables en ciment armé ... In: Le Génie Civil, 1923.
  11. ↑ In Freyssinet's detailed article from 1923 as well as in the one from 1929 there is constant mention of béton armé (reinforced concrete), but nowhere of béton précontraint (prestressed concrete). When later authors write Orly of prestressed concrete in connection with the airship hangar , it springs from their imagination, but has nothing to do with reality.
  12. ↑ Freyssinet wrote in his 1929 article in the Bulletin Technique de la Suisse Romande that he had built the halls in 1923-24 . The article in L'Aéronautique of February 1923 shows in its photos that the state of construction is so advanced that the formal start of construction must have taken place in 1922.

Coordinates: 48 ° 43 ′ 29 "  N , 2 ° 22 ′ 44"  E