WO1993020290A1

WO1993020290A1 - Foundation arrangement

Info

Publication number: WO1993020290A1
Application number: PCT/FI1993/000131
Authority: WO
Inventors: Casper Ålander; Tarmo Mononen
Original assignee: Dalsbruk Oy Ab
Priority date: 1992-03-30
Filing date: 1993-03-30
Publication date: 1993-10-14
Also published as: DK171184B1; FI92623B; SE507216C2; NO306823B1; SE9403275D0; FI921396A; FI921396A0; DK113694A; DE4391341B4; SE9403275L; NO943615D0; FI92623C; NO943615L; DE4391341T1

Abstract

A foundation arrangement which is made up of a cylindrical single-use shuttering mantle (1) which will remain as the surface of the cast concrete, the mantle being in the main made of corrugated metal sheet, and of a mainly horizontal concrete reinforcement which will remain inside the cast concrete. The longitudinal direction (P) of the corrugations is substantially perpendicular to the axis (A) of the cylindrical shape and the shuttering mantle (1) is substantially without bracing. The concrete reinforcement comprises reinforcement elements in which the ends of adjacently positioned reinforcement bars are interconnected by a transverse bar.

Description

Foundation arrangement

The invention relates to a foundation arrangement which is mad up of a cylindrical single-use shuttering mantle which will remain as the surface of cast concrete, the shuttering mantle being primarily made of corrugated metal sheeting in which the longitudinal direction of the corrugations is substantially perpendicular to the axial line of the cylindrical shape, and of a mainly horizontal reinforcement which will remain inside the cast concrete.

Finnish patent 84 926 describes a single-use, mainly rectangu¬ lar shuttering configuration which is suitable for foundation shuttering. A rectangular foundation is subjected by the cast¬ ing pressure or by pressure caused by backfilling to bending stresses in the shuttering wall, and the structure becomes heavy. Rectangular foundation shuttering also involves a great deal of assembling work owing to its structure. For these reasons such shuttering is expensive and poorly competitive.

Finnish patent 74 096 discloses a groundbearing foundation structure, based on concrete shuttering. Such foundation shut¬ tering is heavy and large in size, and therefore difficult and expensive to transport and to handle on site.

Publications US-2 519 575 and DE-31 21 418 disclose cylindrica foundation shuttering based on a resilient and easily bendable shuttering wall made of metal sheeting. For this purpose there is used in the former publication a corrugated metal sheet which is bent so that the longitudinal direction of the cor¬ rugations will run parallel to the cylinder axis, and in the latter publication a smooth metal sheet. In both cases, bracin bands are required to keep the shuttering wall in the correct shape during casting; this makes the structure complicated and increases the cost. Publication DE-587 344 discloses a driven pile which is made up of a plurality of mantle components placed in succession, with their diameters decreasing step-wise from top to bottom, the components being spiral-shaped and provided with protective and bracing collars. Inside the mantle part there is, during pile- driving, a pile core, which is thereafter removed, whereafter concrete is cast inside the mantle. The result is a long con¬ crete pile. The disclosed structure and procedure are in no way practicable in conventional foundation work in which the foun¬ dation is cast directly on the ground at the bottom of an exca¬ vation or, when necessary, on a driven pile already in the ground, in order to distribute the load further.

So-called spiral-weld piping has also been used for cylindrical foundation shuttering. Since the metal sheet must be thin in order to enable the spiral welds to be made, such shuttering is poorly resistant to the casting pressure and to the pressure of possible backfill. This plus the fact that such shuttering must be transported whole to the construction site limit the usable size to a very small size.

The state-of-the-art reinforcement of a cylindrical groundbear¬ ing foundation is very complicated; two different structures have been applied. First, it is possible to use an arrangement resembling an orthogonal net, in which case the bar components of the reinforcement are of substantially different lengths and, furthermore, the ends of the bars have been bent up in order to achieve sufficient anchoring capacity. Another known system is to use curved bars parallel to the periphery, in which case both the bending radius and the peripheral length change along the bottom of the foundation. These reinforcements are based, among other things, on the idea that there should not be left substantial gaps in the reinforcement but it should be comprehensive. Both of these reinforcement systems are dif¬ ficult to manufacture and cumbersome to install. An object of the invention is therefore a foundation arrange¬ ment in which the shuttering mantle would be very light and simple and would also fit in very small space and be therefore easy to transport and handle, but it would nevertheless with¬ stand the pressure of concrete casting. An object is a arrange ment of this type in which also the reinforcing of the concret would be easy and rapid but would provide good strength. A. further object of the invention is a shuttering mantle of this type, which would also withstand, before the casting of the concrete, the pressure of the outside soil, without specific support structures.

The problems described above can be solved and the objects defined above can be achieved with a foundation according to the invention, which is characterized in what is stated in the characterization clause of Claim 1.

It is the most important advantage of the invention that the shuttering structure of the foundation is very simple and inex pensive, and that owing to its small size and light weight it is easy to handle. The shuttering for the foundation is, how¬ ever, so strong that backfilling can be done immediately after the installation of the shuttering, in which case the area of the foundation of the building can be made flat. This makes th casting of the concrete easy, since all the shuttering is ac¬ cessible to, for example, vehicles for concrete feeding. It is surprising that the reinforcement system according to the in¬ vention, leaving unreinforced sectors and segments, provides a high strength in this cylindrical shuttering.

The invention is described below in detail, with reference to the accompanying drawings.

Figure 1 is an axonometric representation of the shuttering mantle of a foundation according to the invention. Figures 2A-2C depict three different corrugation shapes for the shuttering mantle.

Figure 3 depicts the placing of the reinforcement elements according to the invention inside the shuttering.

Figure 4 depicts one application of the shuttering mantle ac¬ cording to the invention.

Figure 1 shows a cylindrical single-use shuttering mantle 1 for the foundation according to the invention, the mantle remaining as the surface of the cast concrete and being made of corru¬ gated metal sheet. In the shuttering mantle 1 the longitudinal direction P of the corrugations is substantially perpendicular to the axis A of the cylindrical shape. This shuttering mantle 1 is assembled from two or more corrugated metal sheet pieces which have been bent into a curved shape. In Figure 1, the cylindrical shuttering mantle has been made of two semi¬ circular corrugated metal sheet pieces 6a and 6b by intercon¬ necting them at their ends by joints 7 transverse to the longi¬ tudinal direction P of the corrugations. As the longitudinal direction P of the corrugations runs parallel to the periphery of the cylindrical shuttering mantle, the result is a mantle structure very rigid in nature, not requiring extra bracing elements. In other words, the shuttering mantle 1 does not re¬ quire bands parallel to the circumference nor beam-like bracing elements parallel to the axis A, since the shape of the corru¬ gations stiffens the structure so that the shape of the periph¬ ery will not change and the cylindrical shape of the shuttering will prevent axial deformation. A mantle made up of two or more components enables, for example, the mantle components to be stacked for transportation and storage, thus improving effi¬ ciency.

According to the invention, the shuttering mantle is formed from corrugated metal sheet pieces, known per se, by bending them in the direction of the corrugations P into curved piece Figure 2A shows a corrugated metal sheet component with tra¬ pezoidal corrugations. Figure 2B shows a corrugated metal she component with curved corrugations, and Figure 2C shows a cor rugated metal sheet component with dovetail-r aped corruga¬ tions, all of them being advantageous for u..? or the j duc- tion of a shuttering mantle according to the vention. If th shuttering mantle is made of two corrugated-. _jet pieces, two pieces are bent into a shape which is slightly longer than a semi-circle, and the pieces are interconnected by overlapping them at their free edges, as shown in Figure 1. In a corre¬ sponding manner, if it is desired to make the shuttering mant of three or four or more pieces of corrugated metal sheet, th are bent into shorter arc segments, which are connected to ea other by overlapping them at their free edges.

The joints 7 of the corrugated metal sheets can be implemente for example, by means of self-drilling screws 8, pop rivets, gluing, seaming, welding, or by some other method suitable fo the purpose. These transverse joints 7 c.n be made advanta¬ geously on the site of installation of t _e foundation, in whi case the transporting of the foundation ; antle is simple, sin the mantle is made up of two or more components. The joints 7 or their pre-shaping can, of course, also be effected in con¬ nection with the forming of the corrugated metal sheet, for e ample, at the factory. In such a case the shuttering mantles may, of course, require somewhat more space in transportation In any case, the transportation of the shuttering mantles is very simple owing to their low weight. On the construction site, the assembling according to the first-mentioned embodi¬ ment is very simple, since extra bracing elements are not needed and the joints 7 can be made by almost any suitable jointing method that can be carried out at any construction site. The foundation arrangement according to the invention also includes concrete reinforcement 2 made up of reinforcement elements 3, each reinforcement element 3 being made up of a plurality of reinforcement bars 4 placed adjacently and prefer¬ ably in parallel, these bars being interconnected at their ends or at a point close to their ends by one of several transverse bars 5. The joints between the parallel reinforcement bars 4 and the transverse bars 5 are preferably made strong by weld¬ ing, in which case the transverse bars at the same time serve as effective anchoring for the main bars 4. For the concrete casting of the foundation, two or more reinforcement elements 3 are placed inside a shuttering mantle 1, transverse in relation to each other, as can be seen in Figure 3. Preferably these reinforcement elements 3 are perpendicular to each other. This structure of the concrete reinforcement effectively distributes loads in the axial direction A over the cross-sectional area of the foundation, and in particular the transverse bars 5 anchor the ends of the reinforcement bars 4. It is clear that even a greater number of reinforcement elements according to the in¬ vention can be placed in the foundation, and in a different manner.

Since the shuttering mantle according to the invention is very strong and rigid to bear both external and internal loads, it is possible, firstly, on the site to act so that the surround¬ ings of the installed foundation shuttering is backfilled with soil up to the level of the final surface, in which case it will be easy to cast the concrete from flat ground. Another structure made possible by the shuttering mantle according to the invention is to place two shuttering mantles I¹ and 1" one inside the other, to place the concrete reinforcement, and to cast the concrete into the annular space 9 between the mantles. In this structure according to the invention, the inside 10 of the inner shuttering mantle 1' can either be left unfilled or be filled afterwards with a less expensive backfill material of a lower quality. This method of use is shown in Figure 4. By means of two shuttering mantles of different diameters it is also possible to implement a precise height of the upper sur¬ face of the foundation regardless of the varying height of th foundation bed. This can be implemented by placing the shutte ing mantle having the greater diameter to bear directly on th ground, regardless of its height, and by placing the shutteri mantle having smaller diameter at the correct height with re¬ spect to its upper surface, whereafter both the space between the shuttering mantles and the inside of the inner shuttering mantle can be cast full of concrete in one casting.

Typically the foundation arrangement according to the inven¬ tion, described above, uses circular cylindrical shuttering mantles, but this is not necessary; it is possible to use shu tering mantles having an oval or some.other shape, according need. Thus the shuttering mantles may also have triangular, square or polygonal cross sections, with rounded angles and a least somewhat outwardly convex sides. A foundation unit or combination, of a suitable shape for each given purpose, can composed of these.

Claims

1. A foundation arrangement which comprises a cylindrical single-use shuttering mantle (1) which will remain as the sur¬ face of the cast concrete, the mantle being made mainly of cor¬ rugated metal sheet in which the longitudinal direction (P) of the corrugations is substantially perpendicular to the axis (A) of the cylindrical shape and of concrete reinforcement (2) which is in the main horizontal and will remain inside the cast concrete, characterized in that the shuttering mantle (1) is substantially without bracing and is made up of two or more corrugated metal sheet pieces (6a, 6b), which are curved in the direction of the corrugations and are interconnected with joints (7), without bracing and transverse to the longitudinal direction (P) of the corrugations, to form a cylindrical shut¬ tering mantle, and that the concrete reinforcement (2) com¬ prises reinforcement elements (3) known per se, each of the elements being made up of a plurality of adjacently located reinforcement bars (4) which are interconnected in the area of their ends by means of a transverse bar or transverse bars (5) .

2. A foundation arrangement according to Claim 1, charac¬ terized in that the said joints have been made by using self- drilling screws (8), pop rivets, by gluing, seaming, welding or by a corresponding method and/or by overlapping the edges of the corrugated metal sheets.

3. A foundation arrangement according to Claim 1, charac¬ terized in that the concrete reinforcement (2) comprises rein¬ forcement elements (3) placed crosswise, preferably perpen¬ dicularly, in relation to each other.

4. A foundation arrangement according to Claim 1, charac¬ terized in that the foundation shuttering comprises two shut¬ tering mantles (!' and 1") of different diameters, placed ap¬ proximately concentrically, the concrete reinforcement (2) being placed and the concrete being cast between (9) the mantles.

5. A foundation arrangement according to Claim 1, charac¬ terized in that the shuttering mantle (1) is, in a section per pendicular to the axis (A), a circle, an oval, a rounded tri¬ angle, square or polygon.