FI63465B - FORM FOER BJAELKLAG - Google Patents

Description

γβί / ^ advertisementPublish, su c-lj \ £ c jöA 1 J * 'UTLÄGG NINGSSKRI FT 63465 CW Patent -nycnnr f, ty 3.0 06 1933 v4B # T / Patent neddelat' /β </enκ.·Λ-β.3 E 04 G 11 AO, (51) Kv.ik. / With the following: a £ Q4 b 5/29, 5/40 FINLAND — FINLAND (21) 7β2ΐ «α • (22) H» k * ml * p4Jvt — Aiwelutlnfsdtf 03.07.78 * * (23) Alkupllvi — OMglntadag 03 = 07.78 (41) Tullut lulkMul —Sllvtt effiMCUg gl + 01 80 «aMsaasaayas (32) (33) (31)« uoHwm »- faglrd a priori» · »(71) SSAB Svenskt Stäl Aktiebolag, S-781 81+ Borlänge, Sweden -Sverige (SE) (72) Sigmund Gräsvik, Borlänge, Sweden-Sverige (SE) (7! +) Berggren Oy Ab (5I +) Award mold - Form för bjälklag

The present invention relates to an arrangement for molding concrete slabs using a hat-profiled steel plate for forming beams and a trapezoidal-profiled building plate for intermediate slabs. Both ends of the building board are flattened partly to provide a tight shape and partly to form a fastener for the board in concrete.

In recent years, the construction industry has in some contexts sought to build houses with large unsupported spaces. The reason for this may be that these large vacant spaces are needed, for example, in large department stores, or that partitions could in the future be moved unhindered at floor levels. One construction method is to form the beam into ribbed tiles. By ribbed tiles is meant here that a plurality of parallel, elongated, box-like beams are cast on the ceiling above the free space in the same connection and on the other hand a slab forming the floor of the layer above is cast above them.

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Of course, the general way in which molds are built from timber can be used in molding. However, this method is both time consuming and expensive, and after tearing the molds, a fairly thorough finishing must be performed to obtain a good structure.

Another and more modern way of shaping is described e.g. in Swedish Patents 320,784 and 381,812. However, the recoverable tear molds described in these have several disadvantages. On the one hand, it is in the nature of the case that the dimensions of the beam are completely dependent on the mold material available and, on the other hand, the distance between the beams adjacent to the beam is very limited for strength reasons. The material used for the molds allows a maximum center spacing of 120 cm between the beams. In addition, the weight of the concrete, reinforcement and molds during casting require a considerable support structure for the molds.

To facilitate the molding and casting of the ribbed plate, the aim is therefore partly to reduce the number of beams by increasing the distance between the beams, partly to make the molds of the beams so rigid that they do not need to be supported in so many places, and partly to reduce the finish.

According to the present invention, molding and concrete casting can be greatly simplified. Hat beams with an opening turned outwards are used as the formwork for the concrete beams included in the ribbed slab, and the trapezoidal steel sheet normally available on the market is used as the mold for the intermediate slabs. The steel plates are positioned so that the direction of the profile is perpendicular to the longitudinal direction of the hat beams. The ends of the steel plates are flattened conically to a length corresponding to the width of the edges of the beam. The trapezoidal profiled sheet is also allowed to remain on the underside of the cast ribbed plate, which reduces the finish.

An example of hat bars is described in Swedish Patent Application No. 71-14893-6. The lateral inclination against the plane of symmetry specified in the description need not be observed here. However, it should preferably be above 0 °, as this will make it easier to remove the hat-beams after casting the ribbed concrete slab.

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The invention will now be described with reference to the figures, embodiments and claims.

Figure 1 shows the rib plate in cross section.

Figure 2 shows a profiled building board which is flattened conically at its ends.

Figure 3 shows a cross section through a flattened head.

Figure 4 shows a building board assembled together with hat-profiled beams.

Figure 5 shows a cross-section of a hat beam according to SE patent application No. 71-14893-6.

By bending the steel plates, molds are made for the underside 7 of the concrete beams. These are formed into hat beams 5 and placed at the desired location on the construction site. The reward is often cast in parts. Suitable lengths are cut from a trapezoidal profiled steel sheet 1 for construction and with a load and length-adjusted profile 2, which are flattened conically at both ends 3. The flattening length corresponds to the width of the horizontal part 8 of the hat beam , the direction of the profile being perpendicular to these. To support the web 7 of the hat beams and to hold the building tiles in place during casting, these can be fastened with bolted joints 10 to the edges of the hat beams. Once the reinforcing steels have been placed in place and the additional molding work has been completed, part of the concrete is cast. The hat beams are removed and used to cast other parts, while the building board 1 is left in place to reduce the finish. The slabs are then held in concrete, partly by means of a direct adhesion between the concrete surface and the slab surface, and partly by means of pockets formed by flattening the ends 4 of the building slab.

Working Example

For the hospital building, the ribbed thickness was dimensioned to be 100 mm (dimension E in Figure 1). The height of the concrete beams, measured from their lower surface to the upper surface of the ribbed slab, was determined to be 456 mm. The maximum span of the ribbed plate was 10.0 m.

The center spacing between the beams was set at 2400 mm. The distance between the supports supporting the beam is 2.0 meters.

The thickness of the trapezoidal profiled building boards was 0.8 mm, including the zinc coating, the profile height was 50 mm, the upper flange width was 63 mm and the lower flange width was 60 mm. The upper flange had a reinforcement groove and the lower flange had two reinforcement grooves.

The calculations have been performed according to the following definitions:

Statens betongkommittä: "Bestämmelser för betongkonstruktioner" and Statens Planverk, godkännanderegler nr 3: "Tunnplätkonstruktioner".

(State Concrete Committee: "Regulations on Concrete Structures" and

State Planning Department, Approval Regulations No. 3: "Sheet Metal Structures").

The following values were obtained for the hat beams:

Reduced axial moment of inertia I = 1596 cm X 3

Reduced cross-sectional resistance Wx = 84.25 cm

Permissible torque with safety factor 1.5 19660 Nm

Permissible support reaction for 100 mm support width 21216 N

The following values were obtained for trapezoidal profiled building boards:

Reduced axial moment of inertia 413 cm / m plate width

Permissible torque with a safety factor of 1.5 3800 Nm / m plate width

Permitted support reaction with 45 mm support width 19820 N / m plate width

Checking trapezoidal profiled building boards for the weight of building concrete and own weight 100 mm thick concrete 2980 N / m ^

Trapezoidal profiled plate weight 90 "

Amount 3070 N / m 2 5 63465

Torque on building boards in the middle of two hatches 2 = 124 3 Nm / m board width

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Support reaction force on building boards = 2763 N / m plate width

Trapezoidal prof Checking the deflection of the treated building board

Deflection —5 * 3/07 * - = o, 48 cm 384-2.1 * 10 ° * 41.3

Allowed 0.60 cm

Checking the hat beam for the weight of the building concrete as well as the own weight Concrete in the beam 1983 N / running meter Concrete in the plate 7368 N / running meter Sum 9351 N / running meter 2

Torque with support 9351 · 2 - = 4 675 Nm

Support reaction force with support

9351 * 2 * 1.1 = 20572 N

Checking the span area of simply prestressed slabs Beam height 456 mm

With a tensile reinforcement cover layer of 30 mm, the effective height is 426 mm. The permissible span is then 10.22 m.