foundation
A foundation (from Latin fundus , soil, in Switzerland also foundation ) is part of the general foundation in the construction industry . It consists of elements such as slabs , piles ( pile foundation , see pile foundation ), beams , stones and the like. Nowadays the foundation is mainly made of reinforced concrete .
The foundation attaches a lighter or more delicate structure to a massive beam. Foundations are usually heavier, stiffer and more resistant to vibrations than the components to be fastened to them. They are unintended motion or deformation prevent the connected structure and have safety against heave offering, which they calculated to be. Foundations are the interface between different functional and structural areas. They often meet the functional criteria of both the load-bearing and the fixed structure. Special forms serve to decouple or separate structures (e.g. elastic foundations or active supports ). Foundations can also be parts of a larger structure, which in turn is founded.
Foundation types
A distinction is made between the following types of foundations:
- Single or point foundations are mainly used in large-area buildings, such as halls, that rest on a skeleton of columns.
- Quiver foundations carry individual supports thatare supposed to absorbnot only horizontal loads but also torques .
- Strip foundations are most common in Germany. They take over the loads of the load-bearing walls erected on them, while non-load-bearing interior walls are usually erected directly on the floor slab. Their width is often twice the walls standing on them, the exact dimensions and, if necessary, the reinforcement result from the load-bearing capacity of the subsoil. The foundations are often implemented in concrete strength class C20 / 25 or C25 / 30.
- Raft foundations or sole plates are used when single or strip foundations are not economical because of high building loads. It can be more economical to use a base plate even with low loads, as the workload may be less. The entire floor slab is then used as a foundation slab. A foundation slab is always reinforced on the top and bottom. It often protrudes laterally over the outer edge of the (basement) walls. Before concreting the foundation slab, a thin blinding layer of lean concrete and / or a solid PE film is placed on the bottom of the construction pit so that the reinforcement cannot move during concreting and the concrete does not mix with the subsoil. Lately, foundation slabs made of steel fiber concrete have been increasingly manufactured , especially in residential building . The advantage is the much easier production and also the price advantage compared to conventional reinforced concrete slabs.
- Transom foundations are the abutments of bridges, which transfer not only vertical loads but also horizontal loads from bridge arches into the ground. In construction, the support of the two ends of an arch is usually referred to as a strut , which supports its thrust on the surrounding masonry.
The machine foundation as a special form of the foundation
The machine foundation is a special form of the foundation, i.e. a structure as part of a foundation in the foundation. The purpose of the machine foundation is to carry or accommodate the load-bearing (usually lowest) part of stationary machines, the so-called machine frame. The machine frame - often cast in one piece - carries the individual, movable functional groups of the respective machine. Machine frames have no other task than carrying the functional groups (motor, tool holder, control electronics, etc.); they can make up 70–90% of the total mass of a machine. Their large inertial mass , in combination with a suitable design, results in quiet machine running as well as high torsional rigidity and the necessary accuracy of the machine function.
The machine foundation enables complex geometries to be easily assembled on a surface or in a building . In contrast to foundations in the construction industry , machine foundations allow position changes to a certain extent, albeit to a very limited extent. Most machines are designed in such a way that all essential functional groups are fixed to the foundation and are positively guided in terms of their movement possibilities.
Machine foundations are not to be confused with machine frames! As a constructed structure, the latter are only there to connect mechanical and structural groups of structures. Typical examples of machine frames are:
- cast iron body with slide guide on a lathe ;
- steel column with a cast steel base on a column drilling machine .
A special type of machine foundation is the pressure foundation .
In plant construction, the bearing construction of large, powerful drive machines or generators is called the machine foundation. These are often bedded on feathers; and these rest on the actual foundation.
literature
- Karl Josef Witt (Hrsg.): Grundbau-Taschenbuch ; Part 3: Foundations and geotechnical structures. 7th edition, Ernst, Berlin 2 009, ISBN 978-3-433-01846-0 .
- Shamsher Prakash; Vijay K. Puri: Foundations for machines: analysis and design. Wiley, New York 1988, ISBN 0-471-84686-4 (English)
- Janusz Lipinški: foundations and supporting structures for machines. Bauverlag, Wiesbaden 1972
- E. Rausch: Machine foundations and other dynamically stressed building structures. 3rd, revised. u. exp. Ed., VDI-Verl. [in Komm.], Düsseldorf 1959
- Bernd Thurat: Machine, foundation, subsoil: Determination of the overall behavior under static and dynamic loading, shown using the example of machine tools. VDI-Verl., Düsseldorf 1980
- R. Stiefenhofer: Contribution to the calculation of the influence of the setup on the dynamic behavior of machine tools. Dissertation at the Technical University of Munich in 1977.
- Karl H. Lepper: Influence of the foundation on the vibrations of rotors. Dissertation at the TH Darmstadt 1984.
Web links
Individual evidence
- ↑ Strip foundation . ( Memento of the original from March 25, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. www.gartenhaus.de Internet portal, website accessed on March 25, 2014
