SE500785C2 - Beam cladding elements and process for its manufacture - Google Patents

Abstract

The invention relates to a floor element (1) of concrete (2) intended to be prefabricated and which in its inner parts contains spare bodies (6) of considerably lighter material than concrete. The element (1) comprises one in the longitudinal direction, on the upper surface (3) and on the bottom surface (4), equal and upwards directed cumbering determined by a constant cumbering radius (10).

Description

590 785 For elements with longer spans, prestressed reinforcement is used. This preload automatically gives the elements an increase. For longer spans, an increase is also required to compensate for the deflection due to the weight of the elements and the load on the elements. However, the increase through the bias voltage is often quite uncontrolled. This can mean that two elements that are placed next to each other get different elevations. This is especially noticeable when cutting elements and when elements of different lengths are placed next to each other. This often entails time-consuming adjustment work in the form of loading or stamping of elements to get them to the same level before joint casting of the elements can take place.

Another disadvantage of hollow floor slabs is a generally less good dimensional accuracy. This, together with the above-mentioned problem with the elevation, means that relatively thick castings or thick layers of float putty are usually required to achieve the required evenness and surface finish for the floor covering. This detracts from some of the intended advantages of element construction because the pouring or floating putty leveling takes time and large amounts of moisture are added again.

In the same way as with cast-in-place floors, the casting must usually be done after the building has had a roof and walls. The joining of the elements with concrete must, however, be done already in connection with the assembly, as the floors are usually used to stabilize the building. Before the elements are joined, this stabilizing ability is lacking.

An additional disadvantage of the element type is the difficulties of subsequently making larger holes for, for example, shafts and the like. This is because the prestressed reinforcement is then cut and thus the load-bearing capacity is compromised. 590 785 Compared with a traditional cast-in-place floor, it is also difficult to achieve the same toughness and continuity as in the cast-in-place floor. Special joint reinforcement or other devices are usually required to secure the building against progressive landslides.

Recently, data have also emerged which indicate that the elements in certain applications can have a sharp reduction in the transverse force-absorbing ability with reduced safety against shear failure as a result.

The present invention consists of a prefabricated floor slab element of concrete with all the advantages of element construction but without the disadvantages pointed out above for the hollow floor slabs.

In addition, the design and splicing procedure of the element means that the same toughness and continuity can be achieved as with a traditional cast-in-place floor.

The invention is described in more detail with reference to the following drawings, of which Figure 1 Figure 2 Figure 3 elements, Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 8 shows a plan section, cross sections and a longitudinal section of a finished element. shows the principle of casting and shaping, shows the design of the longitudinal joints between two shows the design of the end joint of the element, shows how static interaction can be achieved with a steel beam, shows a division of a long shape into sections, shows examples of how the curve can be achieved, shows examples of the design of the mold sides, shows examples of the design of the end stop and Figure 10 af describes the principle for the manufacture of an element.

With reference to Fig. 1, it is shown how the finished element 1 is built up of concrete 2 with an upper side 3, lower side 4 and two side surfaces 5 and savings bodies 6 of considerably lighter material than concrete molded into the concrete, for example cellular plastic.

The element is not manufactured as a perforated tire in a continuous casting process, but cast according to Fig. 2 up and down in a fixed and upwardly open mold 7. The casting in a solid mold provides a considerably greater dimensional accuracy. The bottom of this mold 8 as well as the upper edges 9 of the long sides have a downwardly directed curvature in the form of a constant radius 10 of the order of 200-300 m. The downwardly directed curvature with a constant radius causes the finished element 1 to have an elevation whose size is a function of the length or span of the element. The elevation as a function of the span at a radius of 250 m is shown in the table.

Span (m) Raise (mm) 4 8 6 18 8 32 12 72 The choice of radius is adjusted so that the reported raise generally corresponds to the calculated deflection at the respective span due to the element's own weight. This means that the elements after assembly become essentially flat. 580 785 The advantage of an overhang in the form of a constant radius is also that the same overhang is always obtained for one and the same element length, regardless of where an element is manufactured in a long element shape. This means that the problems with different level differences between adjacent elements mentioned for the hollow beams do not normally arise even if two adjacent elements would have different lengths.

If in a special case a certain level difference should still occur between two adjacent elements, according to Fig. 3 the longitudinal joint 11 between the elements is designed in such a way that a simple adjustment possibility exists in the form of stirrup bars 12 cast into the longitudinal joint.

By, for example, providing the shackle rods with threads and using a flat steel 13 with holes corresponding to the shackle rods, the elements can easily be adjusted to the same level by means of nuts 14 which are screwed to the shackle rods 12.

Described adjusting device is easy to achieve in the manufacture of current elements by casting in a solid form but impossible or very difficult to achieve in the continuous hollow floor production. The device can also be used to fix the elements to each other before the joint casting takes place. This means that the elements, in contrast to heel decks, function as a stabilizing board even without joint casting. The joint casting can thereby be done at a later stage if desired.

With reference to Fig. 1, Fig. 2 and Fig. 3, it can be mentioned that another very great advantage of the current floor element is that the constant elevation 10 together with a sufficiently smooth upper surface is achieved already in the manufacture of the elements by the upper surface 3 cast downwards, against a smooth mold bottom 8, means that no casting of the elements is required at the construction site. Only the longitudinal joints 11 500 785 between adjacent elements and the joints at the ends of the elements need to be filled with mortar or concrete. This avoids the addition of large amounts of water that a later pouring entails.

The design of the joints in the short ends 15 of the element is shown in Fig. 4. The joint design means that an exposed reinforcement net 16 which is anchored in the element will be cast around in connection with the joint casting. This enables a continuity with the absorption of support moments and thus increased load-bearing capacity and rigidity of the elements can easily be achieved by inserting reinforcement 17 over the support which is cast together with the reinforcement mesh. This provides an effective anchoring to the elements. In the case of hollow floor slabs, this possibility of continuity over support is lacking.

As shown in Fig. 5, the design of the end joints also enables a very effective static cooperation to be easily obtained if the support consists of a cooperation beam by the elements via the end joints 15 and the reinforcing mesh 16 resp. the loose reinforcement 17 is effectively cast together.

In order for the floor element to have great rigidity and load-bearing capacity even at larger spans, a sufficiently large construction height is required. For the current elements, a constant height of 300 mm has been chosen for the normal case. To prevent the elements from becoming too heavy, light savings bodies 6 (fig. 1) have been inserted in the middle of the elements. This means that the element weight for retained load-bearing capacity and rigidity is only just over half the weight of a homogeneous floor with the same height.

The spare bodies are arranged so that a "beam rust system" is formed (beams both along and across the elements). This gives the element a very high rigidity and in general the high rigidity in relation to the weight compared to an equally heavy homogeneous floor layer provides very good sound insulating 500 Not least the transverse beams 18 contribute to an increased rigidity across the element, which is valuable above all for the step sound insulation.

The longitudinal beams 19 also have a purely static function insofar as they transmit shear forces from the tensile reinforcement at the lower edge to the printed plate at the upper edge.

To transmit these shear forces, a shackle reinforcement or the equivalent of the longitudinal beams is required.

If the element joints (longitudinal and transverse joints) are only cast in later, which has been pointed out is possible, the "grid system" which the joints form can be used for drawing pipes and smaller pipes.

Between the beams of the element where the savings bodies are located, bracing for shafts, etc. can also be done easily without compromising the load-bearing capacity.

A suitable way of manufacturing the elements is in a long mold 40-80 m with a steel mold base on a vibrator table. The length is divided into a number of parts, each part containing the previously mentioned radius of curvature of 200-300 m (Fig. 6). Taking out the curvature of the entire long mold would mean too great a level difference between the low point and the high point. A suitable length of section can be 20-30 m. This means a level difference of 200 and 450 mm respectively.

The curvature can suitably be effected by making the legs 20 supporting the mold bottom 8 of different lengths corresponding to the curvature (Fig. 7).

Normal element width is suitably selected to 1200 mm and height 300 mm. The mold sides can be constituted by bent steel profiles 21 assembled according to Fig. 8. In the mold sides there are holes 22 for casting in the previously mentioned adjusting rods 12. 500 785 The end stop can be constituted by steel profiles 23 according to Fig. 9.

Referring to Fig. 10, the manufacture itself preferably proceeds as follows. Specified dimensions etc should be seen as examples and may vary within certain limits. 5) b) c) d) e) f) In the mold 7, end stops 23 corresponding to the element length are arranged and savings molds 24 are inserted for releasing the reinforcing mesh 16 at the element ends.

Reinforcement nets 16, reinforcement stirrups 25 and stirrup bars 12 for element adjustment are arranged in the mold. Additional saving forms 26 for exposing the reinforcing mesh at the ends are placed on top of the reinforcing mesh 16.

A first approximately 70 mm thick concrete layer 27 is cast in the mold and vibrated.

Cellular plastic block 6 approx. 180x850, x 1500 is laid in the mold on top of the newly cast first concrete layer 27.

Reinforcing mesh 28 is laid on top of the foam blocks 6 and the remaining concrete 28 is cast. The top side (underside of the finished element) is peeled off to the desired smoothness. Heating is possible for faster hardening.

The elements are lifted out of the mold 7 via lifting hooks 30 in the end stop 23.

Claims (8)

PATENT REQUIREMENTS Floor elements (1) of concrete (2), intended for prefabrication, in their parts containing molded-in spare parts (6) of considerably lighter material than concrete, characterized in that the element (1) has a longitudinal, on the upper side (3) and the underside (4) equal in size and upward curvature determined by a constant radius of curvature (10). Floor element (1) according to claim 1, characterized in that the radius of curvature (10) is between 200 and 300 m. Floor element (1) according to one of the preceding claims, characterized in that the upper side (3) of the element is so smooth that no casting or leveling is required, but a floor covering can be laid directly on the elements after the joint has been completed. Floor element (1) according to one of the preceding claims, characterized in that special stirrup bars (12) are cast in the longitudinal joints (11) which, together with a flat steel (13) and nuts (14), enable two adjacent elements to be easily adjusted in height. Floor element (1) according to one of the preceding claims, characterized in that the longitudinal joint design (11) with bracket bars (12), flat steel (13) and nuts (14) ensures that the elements function as a stabilizing disc even before casting the joints. 590 'les' (0 Floor element (1) according to one of the preceding claims, characterized in that the short ends of the element have recesses (15) and an exposed reinforcement mesh (16) which enables the elements to be made to statically cooperate effectively statically with a interaction beam by being inserted in place. loose reinforcement (17) is effectively cast together with the beam and the reinforcing mesh (16). Method for producing floor elements (1) from concrete (2) comprising cast-in spare bodies (6) of considerably lighter material than concrete, characterized in that the element (1) is cast up and down in an upwardly open shape (7) whose bottom (8) and sides (9) have an equal and longitudinally downward curvature determined by a constant radius of curvature (10). Method for producing floor elements (1) according to Claim 8, characterized in that the radius of curvature (10) of the mold (7) is between 200 and 300 m.