EP0151626B1

EP0151626B1 - Procedure for making foundations for a structure, and intermediate piece for use in the procedure

Info

Publication number: EP0151626B1
Application number: EP19840903066
Authority: EP
Inventors: Kaj Bergman
Original assignee: RAASEPORIN TIILI Oy
Current assignee: RAASEPORIN TIILI Oy
Priority date: 1983-08-12
Filing date: 1984-07-27
Publication date: 1988-09-28
Also published as: WO1985000842A1; FI74096C; FI74096B; DK147585A; DK152442C; DK147585D0; DK152442B; FI832923A0; HUT41465A; EP0151626A1; DE3474327D1; FI832923A

Abstract

Procedure for making foundations for a structure, such as for halls, houses, bridges having their foundations on the ground, using for foundations a concrete ready-made foundation slab appropriate to serve as mould for concrete pouring and which also contains the requisite reinforcements. The invention furthermore concerns a foundation slab element for use in the procedure of the invention which not only is appropriate to serve as mould for concreting and contains the reinforcement required in concreting but also is suitable to be used in conjunction with sleeve and other juncture elements nowadays commonly used in concrete technology. As taught by the invention, on bearing ground (5), or on ground reinforced by piling (4), is applied a foundation slab element (1) prefabricated of reinforced concrete which constitutes a mould in which have been disposed substantially horizontally running steels (2) preferably distance from the bottom level (7) of the walls (6) of the element (1), whereby the foundation slab constitutes both the mould and the reinforcement, on which if desired may be applied a sleeve element known in itself in the art, or equivalent elements. The foundation slab element of the invention comprises a continuous encircling wall (6) and therewithin a substantially horizontally running reinforcement (2) located in the bottom plane of the encircling wall or advantageously at a distance from the bottom level of the encircling wall (6).

Description

The present invention concerns a method for making the foundations for a structure, in accordance to the preamble of claim 1, and the invention further concerns a foundation slab forming element for use in the method in accordance with the preamble of claim 2.
The structural design and shape of the foundation are dependent on the nature of the bearing ground. A structure standing on rock or on sandy soil may have a much simpler foundation than one on clay soil.
It is possible on sandy soil and equivalent to build directly on the carrying soil, that is, to make a foundation resting on the ground. The foundations are nowadays most often made of reinforced concrete. If the bearing ground is at a depth of 2 to 3 metres, the building may be provided with foundations (slabs) sunk by excavation to this depth. If the bearing ground lies even further down, piling must be provided for foundation, the foundation slabs concreted on the site being arranged on their support.
Slab foundations may also be applied in the case of simple bridges where not only the bearing capacity of the ground is concerned but also the safety of the structure against toppling or slipping.
Up to the latest years, the foundation making has taken place on the building site, without any worthwhile standardisation, and the moulds have most often been made of timber, plywood and sheet steel. Insertion of the reinforcements and concreting has then been done on the site. Since mould assembly and reinforcement-laying are heavy and unclean work and the workers moreover are exposed to inclement weather, to rain and cold, difficulties have recently been experienced in recruiting enough skilled labour to do this work.
With a view to solving these problems, the recent trend has been, as far as possible, to adopt the use of elements in the foundation structures, and there have in fact been developed, and used for foundation elements, foundation slabs and pillar foundations, and foundation beams and separate pillar sleeves in supplementing them. However, the use of foundation elements has been comparatively minimal so far, and they have mainly been applied in industrial halls and small houses. The designing has been mostly object- specific, with the consequence that no design solutions have been reached which would be competitive in relation to concreting on site.
The foundation structure then consists either of a separate slab-like foundation element on which a sleeve, pillar or foundation beam element is fitted. Separate pillar foundation elements are also known, of which are available massive types resembling those concreted on site and types of reduced weight, where the pillar sleeve is connected to the foundation slab. It is also known in prior art to fit the pillar sleeve of an element structure together with a slab concreted on site. The element foundation types mentioned above are best suited for foundations on the ground.
When foundation elements with underside slab known in prior art are used, great accuracy of the earth levelling work is required. Usually it is not possible to use the elements known in the art if the ground has necessitated piling to be done, because this often introduces problems which are technologically and economically insurmountable.
A method for making foundations for a structure and a foundation slab forming element for use in this method according to the preamble of claim 1 and the preamble of claim 2, respectively are known from the SU-A-987,034. In the prior art foundation slab forming element the horizontal principal reinforcement members are attachable to the foundation slab forming element. Therefore they do not provide a load transmitting connection between the cast body and the walls of the foundation slab element.
It is the object of the invention to provide a method for making foundations for a structure and a foundation slab forming element for use in this method according to the preamble of claim 1 and to the preamble of claim 2, respectively, in which a prefabricated foundation slab forming element which is easily usable on the building site can be made rigid so that it is resistant to horizontal tensions.
The features which are characteristic of the method are readable in the characteristic features part of claim 1, and the features characteristic of the foundation slab forming element are readable in the characteristic features part of claim 2.
In the following, the method and the foundation slab forming element are described more closely with reference made to the attached drawings to illustrate one design.

Fig. 1 presents a slab-and-sleeve foundation, applied on ground with piling.
Fig. 2 shows a slab foundation applied on the ground.
Fig. 3 is an axonometric presentation of a slab mould element.

A foundation slab forming element may be manufactured in a plant, by conventional technique, in which case for reinforcement may be used conventional reinforcing steels and the "bottom reinforcement", the principal reinforcement members 2 consist of substantially horizontally placed single steels, which may be disposed e.g. crossing each other, to constitute a net-like structure. It is also possible to use ready- made steels with net configuration or equivalent which meet the requirements imposed on the foundations of structures. The dimensions of the principal reinforcement 2 and the spacing of bars can be freely chosen, considering the stresses that will have to be borne.
An encircling wall 6 of the foundation slab element 1 may be shaped to have desired thickness, as may the size and shape of the foundation slab element 1, to account for the loads which will be imposed on the ultimate structure. The foundation slab element may have the cross section not only of a square but equally it may have a round, elliptic, rectangular or triangular cross section. The principal reinforcement 2 may be Icoated in the bottom plane 7 of the walls 6, but it is to greatest advantage to place it higher than the bottom level of the walls, and substantially horizontally. The principal reinforcement 2 is anchored in the walls 6 of the concrete mould.
The foundation slab element 1 can be transported from the works to the desired site, where it is applied on the ground 5, which may be piled 4 if necessary, in which case the foundation slab is applied in conventional manner upon cut-off piles 4. If desired, to the foundation slab forming element 1 may be fitted a sleeve 3 known in itself in the art, or other fixing elements, such as adhesion steels, formed steels, bolts, etc.; whereupon the slab mould is filled with concrete and the construction work may proceed in normal manner.
The foundation slab element may be used in such cases where it was heretofore only possible to use foundation slabs concreted on site.
The foundation slab element 1 may be manufactured in series production in a plant and, moreover, type foundation slab elements 1 can be achieved with the result that it is possible to achieve conventional structures recurring in element prefabrication, whereby it becomes possible when selecting foundation slab elements 1 for a given construction job to select the element which is most appropriate for the particular loads involved, e.g. with the aid of tables.
The circumstance that types can be established will cause the manufacturing costs to go down, . and elements can be manufactured on stock and they can be transported to the building site at the most proper time. Moreover, the foundation slab element 1 is light, with the result that its transport and installation are easy and the transport and mounting costs are reduced from what they were for conventional foundation slab elements.
The foundation slab element 1 constitutes the mould as well as the reinforcement and it reduces the work to be done on the building site, thereby facilitating and speeding up the construction work, and it requires less professional skill than before on the part of the builder, and it reduces the building costs.
Furthermore, alterations during the construction phase are faster, easier and less expensive than before.

Claims

1. A method for making foundations for a structure, wherein on the ground (5) which is bearing or reinforced by piling (4) or otherwise, there is applied a foundation slab forming element (1), prefabricated of concrete, constituting a mould, said mould having substantially horizontal principal reinforcement members (2) extending across the interior space thereof, and by casting fixing means for a pillar, beam or a sleeve element (3) is embedded in the foundation slab forming element (1), whereby the construction after having been joined by casting functions as a continuous footing, characterized in that the horizontal principal reinforcement members (2) are anchored at their ends in the side walls of the foundation slab forming element (1) during manufacture, whereby the foundation slab forming element (1) constitutes both a mould and a horizontal principal reinforcement, the reinforcement prividing load transmission between the cast concrete and the walls of the element.

2. A foundation slab forming element for use in the method of claim 1, comprising a continuous encircling concrete wall (6) and extending across the interior space of the encircling wall substantially horizontal principal reinforcement members (2), characterized in that the principal reinforcement members (2) are anchored by casting in the encircling wall (6) during the manufacture of the foundation slab forming element.

3. The foundation slab forming element according to claim 2, characterized in that the principal reinforcement members (2) are in the form of a mesh reinforcement or single steels.