DE2338618A1 - REINFORCED CONCRETE CEILING PANEL - Google Patents

Description

DIPL.-ING. A. GRÜNECKER kxm Munich 22 DR.-ING. H. KINKELDEY "** ·", tai * n * i) H TeIe-OnJ? 71 GC Λ DR.-ING. W. STOCKMAIR. Ae. E. ic «* inst Ofi ·» «. Expensive ™ Mn. ™ ,. -! <* ■ * .. PATENT LAWYERS Telex OS-TBSOJ

P 68? 1

July 30, 1973

INSULATION MATERIALS & SERVICES FTY. LTD.

428 Burv; ood Road
Hawthorn, Victoria Australia

Reinforced concrete ceiling slab

The invention relates to a reinforced concrete ceiling slab made of Betei and steel reinforcement parts with predetermined Thermal insulation applied to areas of the underside Material.

Ceiling tiles, floor tiles and roof coverings of the mentioned type often need certain fire safety: 5-norms suffice or a certain degree of fire safety

409809/0866

bid for the pall of a fire. 2338618

Fire safety standards or regulations "usually include the specification of a minimum time during which a ceiling tile has certain specified temperatures without breaking must withstand the average temperature on the side of the plate facing away from the fire and that on individual Points on the side facing away from the fire.

Depending on the type of building in which such a panel is to be installed, it must be able to withstand collapse for a period of one hour, two hours, or sometimes three or four hours. It can also be stipulated that the average temperature on the upper side of the plate facing away from the fire ^{may rise by a maximum of about 139 °} C. and the temperature at individual points on the upper side by a maximum of about 180 ^° C. above the initial temperature.

These requirements are met by a wide variety of ceiling and floor tiles, including those from Concrete, which by means of embedded bars or by means of a continuous base on which a concrete floor is cast, forming profiled steel sheets is reinforced.

Such profiled steel sheets are available in different designs common, but which are usually spaced parallel stiffening ribs widen the larger part of the acting on the floor Absorb tensile stress. In a well-known version such a profiled sheet consists of a flat sheet steel band with spaced apart on the top Welded hollow sheet metal ribs with a rectangular or other cross-sectional shape.

409609/0866

In other versions, the steel sheet is in certain Distances to form upwards protruding, dar.it one-piece hollow ribs are required. The ribs usually have upward diverging sides, so that they are obcm wider than below, which creates a secure connection between the profiled sheet and the floor cast on it guaranteed.

In yet another version, the base plumbs out formed individual sheet metal parts arranged next to one another, which on both sides have a vertical web angled transversely at the top. The adjacent bars two adjacent 31eche are close to one another and the angled upper edge of the one Stegs overlaps that of the other.

So that such a floor or ceiling construction Fire safety regulations are sufficient or an armontensible Providing a degree of fire safety, it must be insulated at the bottom to allow heat to flow from one below Raun to the steel reinforcement, which is initially arranged on the underside and absorbs most of the tensile stresses to delay.

For this purpose, the underside of the ceiling or the like. usually covered with a continuous layer of heat insulating material. The shift can from prefabricated panels or sheets or through Spray a suitable material in place and formed.

Common reinforced ceilings are sometimes used on this Insulated in a way, whereby the thickness of the concrete layer underneath the reinforcement is usually sufficient, isolate the reinforcement to some extent. If it is then necessary, further vmmo insulating To attach material to such a ceiling, "the required layer thickness here is rerinfer al'- · that for the

4GS8G9 / Q366

BATH ORIGINAL

Required insulation of a floor cast on profiled sheets, since the latter alone or at least predominantly from the one attached after completion of the floor or ceiling Insulating material is formed.

The ceilings or floors cast on profile sheets are therefore usually less economical than conventionally reinforced plates, since here the costs for dio additional insulation is required. Serve sit down, regardless of whether it is a prefabricated one or one in place and Manufactured insulation is made from the cost of materials and from the cost of attaching it together.

An important object of the invention is to provide improved and more economical designs of fire-proof floors and to create ceilings and roof coverings.

It was found that one sprayed onto the underside of such a plate by means of conventional equipment Insulating layer made of asbestos fiber, for example, even with the least possible The application thickness of the plate is far greater than that normally required by the applicable regulations gives horizontal heat resistance.

A common ceiling construction made of concrete poured onto a sheet metal base with an approximately 12.7 mm thick insulating layer of sprayed asbestos fiber extending over the entire underside, for example, does not collapse even if it is subjected to the temperatures specified in standardized test regulations for four hours. Obviously, the amount of insulation material used is considerably larger than it would be required for a ceiling, which according to the applicable fire safety regulations only needed a safety period of one or two hours.

Theoretically it would be possible to make the insulation more economical by increasing the thickness of the layer

409809/0866

- BAD ORIGINAL

23386TQ

decreased. If the performance of the. However, the equipment used to apply the layer is considerably longer to cover a given area Time required, which increases the cost of putting the insulation back on. From a reduction in the Insulation thickness does not result in any total cost savings, but possibly even an increase in the total cost.

The strength of the normally agc for a plate term "steel used does not undergo any appreciable change in the range between room temperature and about 23P ⁰ C. A loss of tensile strength does not occur until an at higher temperatures, so that the tensile strength at about 5 ^ 0-594 · C only is still about 60% of that existing at room temperature. If the steel is heated further, there is a very rapid reduction in tensile strength, so that the tensile stress supporting the plate disappears and the plate can collapse.

Reinforced concrete slabs of all types usually have one Safety factor, which allows a load that far exceeds the nominal load before it breaks. The invention is based on the resulting knowledge that insulation for part of the reinforcement, which keeps it at a temperature which is considerably below that at which a rapid. Decay the tensile strength occurs, a rather strong heating of other parts of the reinforcement is allowed before the slab collapses .

Bräch ^ for example, a completely insulated plate of a certain type for a period of four to five hours, during which the temperature of the reinforcement reaches about 594 ⁰ C, together, would break an isolated only on specific disc of the same type for a period of two up to three hours together, during which the temperature of the insulated reinforcement rises to about 3 ^ 5 C,

409808/0886

D.ies true despite the fact to that the temperature of the non-insulated steel reinforcement can thereby increase considerably over about 594 · ⁰ C and is attributable to the fact that no longer absorbed by the non-insulated reinforcement at the elevated temperature tensile stresses nor by the isolated parts of the reinforcement.

However, difficulties can arise with regard to the regulations on the permissible temperature rise at the top of the plate. For a given thickness of dense concrete, the rate of temperature rise at the top depends on the water content of the concrete. As long as the concrete still contains V / ater, the temperature increase is quite slow and is only _y faster when the .gesarate V / ater has evaporated.

Practical experiments with a single, mutually spaced strips of insulating material] isolated slab have shown that the concrete to the. Part of the heat supplied to the non-insulated areas isolated areas and there as evaporation is used to evaporate the water. So if the distances between adjacent strips of the Insulation is not too great, that is for the rise the temperature on the surface to that in the test specification given values, the time required for a partially insulated panel is almost as long as for a entirely isolated plate.

It may be found, if necessary, that one is to prevent the breakdown of the panel by sacrificing strength the reinforcement sufficient width and arrangement of the isolated areas ncith is sufficient, the Tomperatur at the Keep top of the plate within the prescribed limits ru. In this case the way out is that Increase the width of the insulating strips, see below, the distances

BAP

between the strips to decrease the thickness of the plate to increase and / or instead of a dense concrete one Use lightweight concrete for the plate. The decision for one or the other measure depends on the profitability the construction as a whole. In any case i.st but the insulated portion of the platoon width considerably smaller than the goramte width of the plate.

In a concrete slab of the type mentioned above of the invention provided that a total of not more than 80% the exposed underside of the plate with the insulating material are covered and that the predetermined areas are chosen so that when the steel reinforcement is heated on the non-insulated areas, significantly impairing their ability to absorb tensile stresses Temperatures due to a fire below the plate can no longer be absorbed by the unprotected reinforcement Tensile stresses are absorbed by the steel reinforcement protected by the insulating material.

The proportion of the isolated areas preferably does not exceed 50% of the total area of the underside of the plate.

While so far the undersides of reinforced concrete ceilings and the like by cladding the entire area iait a substantially uniformly thick layer of insulating material were isolated, the invention provides the application of insulating material only or predominantly on such Make the bottom gate where it is most effective and the creep speed of the steel at a 3rand holds below a value for a certain period of time, in the event of a break in the plate.

In this way, a given fire safety can be achieved with a reduced amount of insulating material, from which both in terms of the material itself and in terms of the time required to apply it result in considerable savings, regardless of whether the insulating

40S802 / 0866

BATH ORIGINAL

material is prefabricated or only on site will be produced.

The following are exemplary embodiments of the invention described with reference to the drawing. Therein zeipi ;:

1 shows a cross-sectional view of a reinforced concrete floor or ceiling plate in Forin on a base made of sheet metal profiles "known execution poured concrete slab with insulating material attached to individual areas of the underside,

FIG. 2 shows a view corresponding to FIG. 1 with a different arrangement of the insulating material,

Fig. 3 is a cross-sectional view of a reinforced concrete slab with a different type of reinforcement,

Fig. 4- is a view corresponding to the preceding figures with a third version of the reinforcement,

5 is a view corresponding to the preceding figures with a fourth version of the reinforcement,

6 shows a view corresponding to the preceding figures with a fifth form of reinforcement,

7 shows a view corresponding to FIG. 6 with a modified one Arrangement of the insulation material with the same type of reinforcement,

8 shows a view corresponding to the preceding figures with a sixth embodiment of the reinforcement,

9 shows a view corresponding to FIG. 8 with a modified one Arrangement of the insulation material with the same type of reinforcement,

409809/0866

2338619

Fig. 10 is a cross-sectional view of a conventional armored one Concrete slab with a possible arrangement of insulation,

11 is a sectional view of a reinforced concrete slab at a right angle to the cutting line in FIG. 1 to 10,

FIG. 12 shows a view corresponding to FIG. 11 with a hindered view Arrangement of insulation and

Fig. 13 is a view corresponding to the previous one of a modified one Arrangement of the insulation for a continuously reinforced concrete slab.

The reinforced concrete floor or ceiling slab shown in Fig. 1 has a number of reinforcement parts 10 with wide, flat U-profile. On the upright thighs 13 of the U-profiles 10 is angled transversely in each case of the upper hand 12. The edge 12 is used to pre-bind adjacent profiles. For pouring the concrete slab. are the reinforcement parts 10 in a suitable manner Arranged beams of a building and then serve as a base or form in which the concrete 14- is poured. On the underside of the plate is an insulating material 16 in parallel to the reinforcement parts and those between them strips covering lying joints. The insulating material can, as shown in Fig. 1, in the form prefabricated strips or tapes attached or sprayed on as an insulating compound. For isolation suitable materials include sprayed asbestos fiber, sprayed cementitious mixtures, such as a mixture made of Gfps and vermiculite, expandable paints, or even on On-the-spot castable fabrics, pre-formed profiles, pre-fabricated panels, strips and tapes and pre-fabricated Sheets and mats made of materials with insulating properties, with or without the use of binders. Generally any suitable material can be used for this.

409809/0806

ίο. ■

The individual insulating strips 16 are each symmetrical over the joint between "adjacent reinforcement parts" 10 attached and extend on both sides over this. The applicable width of each Strip is depending on the required for the plate, fire safety related to the duration, the Thickness of the plate and the ercite of the individual reinforcement parts different. The one protected by the insulating material The proportion of non-reinforced steel is considerably greater than the part of the underside of the covered by the insulation Plate, as the legs of the profiles that reach into the concrete are also protected.

In practical tests it was found to be considerable less than 50/6 of the panel width with the insulation material need to be covered, un under standardized test conditions a tensile strength of the steel reinforcement that delays the breakage of the plate for two hours or more maintain. When casting a plate with the one shown Type of reinforcement creates such a firm connection between the concrete and the reinforcement that pure arithmetically almost all of the tensile stresses from the legs of the profiles that extend into the concrete and the areas of the flat parts of the base immediately adjacent to them. The insulation strips from the in? ig. 1 thus cover essentially the entire width for recording the required width of the reinforcement parts for the tensile stresses.

Pig. Fig. 2 shows another type of insulating material in one changed arrangement. The insulation is applied here in wider Streifih than in Fig. 1, so that the one Strips 18 over more than the width of one reinforcement part 10 reach away. In the embodiment shown, the insulating strips each extend over two joints of the reinforcement parts and more about the "Both joints, and sufficient insulation for to ensure the legs of the U-profiles. The distances

'· 409809/0866 bad or _1GI nal

233861?

between the edges of adjacent insulating strips are slightly smaller than the width of the individual reinforcement parts shown. Unless there are requirements regarding Allow strength and heat transfer, but the distances can also be greater than 3cin.

In Pig. 2 shows an insulation made of sprayed-on material, but any other type of insulation can be used instead of insulating material can be used.

Fig. 3 shows an embodiment of the reinforcement in a cell structure, with air cells 30, which by connecting two offset steel sheets 32, 3 ^ with ki'cneliertera Profile are formed. With this type of reinforcement, different types of insulation can be achieved use. In Fig. 3, two useful versions of the insulation are shown.

In the first embodiment, the insulating material 36 fills in each case a channel 38 between two adjacent ones Elevations 40 of the reinforcement sheet on the underside of the plate and extends over the undersides of the elevations. Depending on the requirements, one or more channels and can be between the individual isolated strips Surveys remain free.

In the second embodiment ^ the insulation 42 is only in the Grooves 38 between the bumps 40 on the underside of the Plate attached. In the drawing, although all the grooves are filled with the insulating material, depending on the to However, other arrangements can also be provided that fulfill the test conditions. For example two adjacent grooves be filled with insulating material, whereupon one groove remains free and then again two gutters are insulated. In other versions, for example, only needs every second or every one third channel to be filled with com insulating material.

409809/0866 B ^ GfitOfNAU

233861?

With this type of reinforcement it is usually appropriate to spraying on the insulating material instead of using prefabricated material. In certain cases, ec is also possible, Pour the insulation material into the gutters before installing the reinforcement for pouring the concrete slab.

Fig. 4 shows a cellular structure of the Reinforcement., There is a flat sheet underlay on one side 46 Welded sheet metal profiles 48 with an overhead U-shape. This in turn creates cavities 50? not however, the grooves 38 in Fig. 3 corresponding Ausnolununp: s on the bottom. The drawing shows the use of prefabricated strips 52 of insulating material, which are attached in approximately their width corresponding mutual spacings, - However, if necessary, a sprayed-on insulating material is used, and the width and spacing of the strips can be changed as desired.

Fig. 5 shows a concrete slab with a different type of Reinforcement. The base on which the concrete slab is poured consists of metal sheets 51 with in certain Ribs 52 formed at intervals and protruding downwards from the underside of the plate. Around the individual ribs 52 around or, as shown in the drawing, around every other rib, or in any other arrangement, which The insulation gives the panel the properties specified by the applicable safety regulations 54 sprayed on.

In Figs. 6 and 7, one is similar to that shown in Fig. 5 Type of reinforcement shown in which the ribs 60 of the base 62 up into the concrete to raise. The insulation 64 is here preferably sprayed on in the manner shown in FIG reaches a short distance into the ribs. However, the ribs do not need to be completely covered with the insulating material

409809/086 *

2338619

to be filled out. Due to the solid material connection between the metal and the Eeton, the Largest part of the tensile stresses purely arithmetically from the ribs and the planes immediately adjacent to them Share the document added. Servant circumstance enables a narrowly defined arrangement of the insulation in the area of the ribs, as shown in FIG. 6 int. In some cases, strips 64 of insulating material can be used each extending over two or more ribs, with the insulation sprayed on or in Form of prefabricated strips can be attached (Fig. 7)

The type of reinforcement shown in FIGS. 8 and 9 is in principle similar to that shown in FIG. 5 and consists of sheets 70 with a crenellated profile, but with only one Plechlage instead of two offset sheets. Optionally, each individual channel 72 or even every second channel can be filled with insulating material 74 (FIG. 8). Depending on the requirements placed on the construction, two or three channels or approximately every third channel can be filled with insulating material . In yet another arrangement, the insulation 76 can each extend over two grooves 72 or over one groove 72 and two elevations adjacent to it (FIG. 9).

The plate shown in FIG. 10 has the conventional structure of a reinforced concrete plate with metal rods 80, 82 arranged in the form of a grid. In such a construction, the main stressed parts of the reinforcement are usually parallel to a pair of longitudinal edges of the slab, while the parts 82 in the main cache extending parallel to the other edges serve to hold the former parts in place.

With such a plate it is not possible to determine the exact Position of the supporting bow miter bars from the bottom to recognize. However, since the heat-insulated steel is one of the

409809/0866

25386TQ

to absorb tensile stress exceeding the calculated nominal load capable, it proves to be sufficient to place the underside of the plate parallel to the supporting one at intervals Reinforcing bars 80 extending strips 84 of insulating material, which each protect some bars, but not all, to insulate. When heated there unprotected Rods are the tensile stresses initially absorbed by them then taken up by the protected bars so that the plate meets the requirements laid down in the regulation to suffice verraag.

Figures 11 and 12 are at right angles to the sectional views 1 to 10 shown sectional views of plates lying on both sides. The plates are on both Ends on an I-beam each. In the embodiment of FIG. 11, the strips 92 of insulation run over the total unsupported length between the straps of the girders.

This arrangement enables considerable savings in labor and material costs for the insulation of the underside of a panel, since the insulation is arranged in strips which cover only part of the entire panel surface.

With such a plate, the bending moments and thus the tensile stresses occurring on the reinforcement near the support points much less than in the middle of the cantilever span. For this reason, the temperature of the Reinforcement near the support points "increase considerably without causing the slab to break.

Fig. 2 shows an embodiment in which the strips of insulating material are shorter than the span of the plate, which results in additional savings.

13 is a sectional view corresponding to FIGS. 11 and 12 a continuous plate resting on several carriers. The left-side span 100 is a: a end

409809/0866 BAD ORIGINAL

233861ft

15 -.

the plate, which is to the right over the adjoining Span 102 continues. The bending moments occurring in this type of plate are in the middle of the individual 'spans positive and negative over the intermediate beams. To accommodate the latter, reinforcement bars 104 are provided above the beams, while the former ■ from a reinforcement of the one shown in Figs. 1 to 10 or another suitable way.

The tensile stresses at the lower instruction only occur between the points at which the negative bending moments become positive at the crest span widths 102. In practice, this distance is around 50 to 60% of the total span. In order to meet the fire safety requirements with regard to the duration, the strips of thermal insulation therefore only need ^{to have a length of about 50a 1 of} the span. However, in order to meet the temperature rise requirements at the top of the plate, it may be necessary to make the strips even longer. Otherwise, the various measures mentioned at the beginning can also be taken, such as increasing the panel thickness and / or using lightweight concrete instead of dense concrete.

As can be seen from the above description, enables the invention significantly reduces the cost of fire-proof insulation on a reinforcement pad 1 to 9 cast or similarly reinforced concrete slabs. Careful calculation of the dimensions and the arrangement of the strips of insulating material allows platinum of this type at the same cost or even cheaper produced as concrete slabs with conventional reinforcement of the type shown in Fig. 10. In a slab with such Reinforcement costs can be reduced by taking the thickness of the concrete below the reinforcement, which anyway does not absorb tensile stresses, and insulating material in individual strips ah the bottom of the plate decreases

409809/0866

o * a

2338619

attaches. Contrary to all expectations, it results from an insulation extending only over certain areas of the underside of a plate does not cause excessive acceleration of the temperature rises at the top of the plate.

409809 / 086S

Claims (8)

Patent claims : 'Reinforced concrete ceiling slab made of concrete and stahlernen mierungstcilen with v / arm-insulating material attached to predetermined areas of the underside,' characterized in that a total of no more than QQ ⁰ A of the exposed underside of the plate (14) with the insulating material (16, 18, 36, 52, 54, 64, 74, 76, 84-) covered and that the predetermined areas are selected so that when the steel reinforcement (10, 30, 46, 51 »62, 70, 80) is not heated insulated areas on their ability to absorb tensile stresses, which can significantly impair temperatures due to a fire below the plate, tensile stresses that can no longer be absorbed by the unprotected reinforcement are absorbed by the steel reinforcement protected by the insulating material. 2. Reinforced concrete slab according to claim 1, characterized in that the isolated areas no more than 50% of the total exposed area at the Identify the underside of the plate. 3. Reinforced concrete slab according to claim 1 or 2, characterized in that the insulation in parallel strips of "certain width and in at certain intervals. 4. Reinforced concrete slab according to at least one of claims 1 to 3 * characterized in that that the steel Armierung3teile consists of sheet metal profiles (10, 30, 46, 51, 62, 70), which at the same time serve as a mold base for pouring the concrete (14). 5. Reinforced concrete slab according to claim 4, characterized in that the Bleehprofilc Have inside (38 »72), and that the insulating material (36, 42, 74, 76) is attached in at least some of the backs. 409809/0866 6. Reinforced concrete slab according to claim 5, characterized in that the steel reinforcement parts; from embedded in the poured concrete steel rods (80, 82) that the .thickness of the unkerhalb the Bars lying concrete is less than normal and that the strips of insulating material (84 x) are independent of the position of the reinforcing bars are attached. 7. Reinforced concrete slab according to claim 4, characterized characterized in that the sheet metal profiles individual bands with arranged on both sides, moving upwards in the concrete extending webs (13 »60) and that the strips of insulating material (16, 18, 64) are attached so as to have at least some of the joints between one another Cover adjacent sheet metal profiles. 8. Reinforced concrete slab according to at least one of claims 1 to 7 » characterized in that the insulating material (18 ,? 6, 54, 64, 74, 76, 84) is sprayed on. 9 «Reinforced concrete slab according to at least one of the Claims 1 to 7 »characterized in that the insulating material is in the form of prefabricated strips (16, 52, 64) is attached. 10 · Reinforced concrete slab according to at least one of claims 1 to 9 »characterized in that the strips of insulating material (92) each do not extend all the way to the support (90) on which the slab rests at both ends. 409809/0866