Flat ceiling

The flat ceiling is a component and describes a beam-less blanket that are usually classified as in-situ concrete - or as a floor slab is carried out.

Flat ceiling

With this support system, the ceiling slab does not transfer its loads into the supports via joists, but is supported at points by supports and any walls. Nowadays the flat ceilings are usually made of reinforced concrete or, in the case of larger spans of around 9 m, of prestressed concrete . The advantages are in particular the simple formwork and manufacture, lower construction height than the beam ceiling, smooth ceiling soffits and, in office buildings, the free routing of the installations and flexibility in the room layout. Disadvantages are the higher floor weight compared to the girder floor, the greater sensitivity to deformation and the more difficult dimensioning of the required reinforcement due to the biaxial load transfer . In particular, the introduction of forces at the prop head must be carefully planned and implemented in order to avoid punching through .

Punching shear reinforcement in a slab reinforcement with an underlying column

If hollow bodies are built into the ceiling as spacers between the load-bearing reinforcement in order to reduce weight, the result is a reduction in the dead weight of 25 to 35 percent compared to the full cross-section, which enables larger spans.

Mushroom ceiling in the Giesshübel warehouse in Zurich

Mushroom blanket

The first blankets without batten were mushroom blankets. With these, the supports below the ceiling are widened in the shape of a mushroom hat. As a result, the load transfer from the slab to the column is better due to a more even distribution of the stresses in the slab. The first mushroom ceilings were built in 1906 by CAP Turner in Minneapolis in the USA, in Europe the Swiss Robert Maillart created the first lumber-free ceilings in 1910 in the warehouse of Mangili Lagerhausgesellschaft AG on Giesshübelstrasse in Zurich.

Slim floor ceiling

With slim-floor flat ceilings, the load is transferred from the ceiling to the supports by steel or composite steel girders installed flush with the ceiling, whereby the ceilings can consist of in-situ concrete or precast concrete parts ( element ceiling ). This ceiling system was developed in Scandinavia and is widely used there.

literature

Gotthard Franz, Kurt Schäfer: Construction theory of reinforced concrete. Volume II: Structures, Part A: Typical Structures . Springer-Verlag Berlin, ISBN 3-540-16861-3 .
Society for civil engineering (ed.): Robert Maillart - concrete virtuoso . 3. Edition. vdf Hochschulverlag AG at the ETH Zurich, Zurich 2007, ISBN 978-3-7281-3104-1 .

Individual evidence

↑ A brief history of the mushroom cover can be found in: Karl-Eugen Kurrer : The History of the Theory of Structures. Searching for Equilibrium . Ernst & Sohn , Berlin 2018, pp. 709–712, ISBN 978-3-433-03229-9
↑ Maillart Robert: On the development of the ceiling in Switzerland and America . In: Schweizerische Bauzeitung . tape 87/88 , no. 21 , 1928, pp. 263-265 , doi : 10.5169 / seals-40893 .

[1] A brief history of the mushroom cover can be found in: Karl-Eugen Kurrer : The History of the Theory of Structures. Searching for Equilibrium . Ernst & Sohn , Berlin 2018, pp. 709–712, ISBN 978-3-433-03229-9

[2] Maillart Robert: On the development of the ceiling in Switzerland and America . In: Schweizerische Bauzeitung . tape 87/88 , no. 21 , 1928, pp. 263-265 , doi : 10.5169 / seals-40893 .