US 3757482 A
A sandwich-slab structure has a front concrete plate and a rear concrete plate which are generally coextensive and sandwich a layer of insulating material, e.g., a sheet or plate of foamed synthetic resin, between them. The layer of insulation is traversed by a plurality of connectors or anchors in the form of tubules or sleeves having opposite ends received in the concrete plates and provided with transverse formations for anchoring the sleeve in each concrete plate, preferably by engagement with a reinforcing mat.
Claims available in
Description (OCR text may contain errors)
1 1 Sept. 11,1973
llnited States Patent 1 Haeussler  SANDWICH SLAB CONSTRUCTION AND 1,661,044 2/1928 Lawrence 52/565 1,072,361 9/1913 52/706 X 1,879,319 52/405 X 2,063,309 2,309,147 2,633,439
ANCHOR THEREFOR 9/1932 Kleitz....... 12/1936 Graef..,........
 Inventor: Ernst I-Iaeussler, Grashofstr 47, 43
Essen-Bredeney, Germany Feb. 22, 1971 Wilkinson Konstandt..........
Primary Examiner Alfred C. Perham Att0rneyKarl F. Ross  Appl. No.: 117,673
 Foreign Application Priority Data Feb. 24, 1970 Germany......,,...........
ABSTRACT 68 6 O 56 %08@ 4/246 yz ,y 5 4wwm5 00 M 5 2 3/ 0 7 2 36 5 w w 5 m 0 0 NW 2 NW6 5 m5 m WW2 m0 3 m u u 00 m Mme m m "s8 h n 3 1 1m r d n U IF H UN 5 55  References Cited and provided with transverse formations for anchoring UNITED STATES PATENTS the sleeve in each concrete plate, preferably by engage ment with a reinforcing mat.
3,383,817 5/1968 Gregori.....,..................,........52/309 2,964,821 12/1960 Meehan 52/410 X 6 Claims, 8 Drawing Figures Cd/VCEETF PATENTEDSEPI Hers sum 1 BF .3
3 came/e575- SANDWICH SLAB CONSTRUCTION AND ANCHOR THEREFOR FIELD OF THE INVENTION The present invention relates to a sandwich-slab construction, especially for the prefabricated and semifabricated erection of concrete structures, to a connector or anchor for the members of a sandwich-slab structure and to a system for assembling a sandwich slab; more particularly, the invention relates to an improved assembly of the type wherein a pair of concrete plates are interconnected in spaced relationship and sandwich an insulating layer between them.
BACKGROUND OF THE INVENTION With increasing efforts to reduce the cost of construction, various proposals have been made with respect to composite wall, slab and plate structures. In general, a composite or laminar structure for construction purposes will comprise a number of layers tied together in a more or less rigid manner, each layer contributing some characteristic to the overall properties of the plate. For example, the sandwich or laminar structure may comprise one or more facing members defining an outer surface of the structure to provide an aesthetic appearance or a desired texture, one or more load-supporting members adapted to support the laminar structure or a suitable carrier or frame or adapted to support another structure on the plate, one or more insulating members or layers designed to resist heat transfer between the inner and outer surfaces of the slab, and one or more core or filler members adapted to provide the desired bulk. It will be evident that one or more of these members can be eliminated, depending upon the physical or aesthetic properties desired or additional members, e.g., sound-insulating layers, may be provided if certain qualities are to be enhanced.
While such laminar constructions have found widespread acceptance where the members were constituted of pressed fiber (fiberboard or hard board), metal, synthetic resin or wood have constituted the members, only of late has a composite concrete slab construction of the sandwich type been successful. A sandwich slab of concrete, which may be used for walls, partitions, load-supporting members, floors, ceilings and roofs of buildings, generally comprises a pair of reinforced-contrete plates'flanking a layer of thermal insulation and sound insulation and held together by anchors which traverse the insulating layer and tie the concrete plates together. The concrete plates and the insulating layer are coextensive or substantially coextensive, i.e., have geometrically congruent outlines and are usually rectangular. The sandwich slab may be fabricated at a factory or plant remote from the construction site, may be transported thereto by any convenient conveyers, and may be erected at the site with cranes or the like. In practice, such slabs are generally anchored by bolts, pins, studs, welding or adhesives to a support frame which may be cast from concrete in situ or which may be erected from steel or the like.
The concrete plates constituting the sandwich slab are reinforced, as noted earlier, and may be provided with a lattice-work of reinforcing bars, rod or wire, previously tied, welded or otherwise joined to form a reinforcing mat. The reinforcing members are generally constituted of steel.
The insulating layer may, of course, be of any of the types accepted in concrete-slab construction and is preferably a relatively rigid plate or sheet. A foamed synthetic resin, e.g., cellular polystyrene, is typical for this layer.
It has hitherto been the practice in the manufacture of such sandwich-slab construction to anchor the reinforcing mat of one concrete plate to the reinforcing mat of the other concrete plate through the insulating layer with, for example, reinforcing rod or wire of M- configuration. Of course, other systems for typing the plates together have been proposed but these, along with the connecting system specifically described, have proved to be unsatisfactory in certain respects. As will be apparent, the concrete slabs are subject to many stresses which not only are extreme, but which may vary over short and long periods of time. For example, from day to night, the slabs are subjected to substantial temperature differentials and variations in temperature and from summer to winter, a major variation in temperature is applied to the slab. The effect of temperature differential will be understood more readily when it is recognized that one concrete plate of the sandwich slab may be exposed predominantly to the outside temperature while the other concrete plate is exposed to the temperatures within the structure. The temperature variations have been found to detrimentally affect the connection between the concrete slabs. Furthermore, the aforementioned systems for tying the concrete slabs together have the disadvantage that the insulating layer, which may be preformed with openings traversed by the tie members, must be prepared with care; the tie members are generally insufiiciently strong to maintain a force-transmitting connection between the concrete plates, etc.
OBJECTS OF THE INVENTION in assembly and mounting than has hitherto been the case.
It is another object of this invention to provide an anchor for connecting concrete plates of a sandwich-slab structure such that the disadvantages enumerated above are obviated.
SUMMARY OF THE INVENTION These objects and others which will become apparent hereinafter, are attained in accordance with the present invention in a system for anchoring a front concrete plate to a rear concrete plate in substantially juxtaposed and coextensive relationship, through an insulating layer interposed between these plates, wherein the anchor comprises an elongated tubule or sleeve provided at opposite extremities received in the respective concrete plates with means engaging them. Such means is preferably located adjacent each edge of the sleeve. According to an important feature of this invention, the tubules or sleeves are tube or pipe sections of a regular cross-section, Le, a cross-section corresponding to that of a conic section or a regular polygon, and preferably which is constant over the entire length of the anchor although it has been found to be advantageous in certain circumstances to provide a constant convergence to the anchor. In the latter case, the anchor sleeve is conical, the conicity assisting in anchoring the concrete plates together.
According to another feature of this invention, the means at each end of the sleeve include arrangements engageable with the reinforcing members of the respective concrete plates and it is preferred to provide lattice-like reinforcements for the latter. In this case, the anchor is dimensioned to extend into an interstice of the reinforcing lattice of each concrete slab and to be provided with laterally outwardly extending formations engageable behind the reinforcing rod or members of the latticework. I
According to a more specific feature of this invention, the anchor sleeves are formed with rows of holes or perforations proximal to their ends while the aforementioned formations receive bars or rods traversing these holes and projecting laterally beyond each anchor to overhang or underlie a reinforcing rod or bar of the lattice. Advantageously, two longitudinally spaced rows of such holes are provided and at least one rod is fitted into each row of holes so that the transverse rods engage on opposite sides of the reinforcing mats. Each row of holes will generally include a number of pairs of diametrically opposite perforations which are aligned to permit the transverse rod to extend through them.
In addition or in the alternative, the means for locking the sleeves within the concrete plates can include tabs or lugs which may be bent outwardly to project laterally.
Still another object of the invention resides in the insertion into the sleeve of a plug of insulating material to prevent thermal losses through these anchors. The plug may be punched from the insulating plate in the formation of the opening through which the: anchor is to extend and the punching may be effected by driving the sleeve into the insulating layer at the time the sleeve is mounted, the plug of insulating material remaining within this sleeve. While the anchor is constituted of metal, preferably steel, and may be cut from a pipe or tube or built up from steel plates or bent from sheet metal, other materials may be used according to the physical properties desired.
The system of the present invention provides a large effective diameter linking the two concrete plates and hence involves a force-transmission which is distributed over a large area by virtue of the large diameter and cross-section of the anchor. The steel sleeves in the concrete have substantially coincident coefficients of thermal expansion and the relatively thin steel sleeve is generally at the same temperature as the concrete so that thermal stresses are minimized. Since the sleeves act as force-transmitting columns, shear stresses of the slab parallel to the concrete plates have little effect and, since the sleeve always extend perpendicular to the concrete plates, the sleeves are tortionally rigid and can take up the necessary stresses when the sandwich slab is rotated in its plane during mounting. It has already been observed that the slabs can be used to form facades, roofs and load-supporting walkways and floors.
DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the following drawing in which:
FIG. 1 is a cross-section perpendicular to the plane of sandwich slab according to the invention, illustrating the anchor assembly in elevation;
FIG. 2 is a view taken in the direction of arrow II and partly broken away;
FIG. 3 is a cross-section taken along the line Ill III of FIG. 1;
FIGS. 4 6 are perspective views illustrating other anchor sleeves according to the invention;
FIG. 7 is a perspective view showing another assembly using an anchor sleeve according to the invention; and
FIG. 8 is a plan view showing the structural member of the present invention.
SPECIFIC DESCRIPTION The sandwich slab construction of the present invention may, as shown diagrammatically in FIG. 8, comprise a rear concrete slab I03 having a mat 106 of reinforcing rod embedded therein and of generally rectangular configuration. The concrete plate 103 is coextensive with a slab or plate of cellular synthetic resin as represented at 102, this insulating layer of foamed polystyrene, for example, being overlain by the upper plate 101 of concrete. The plates are interconnected by anchor sleeves generally represented at 104 at spaced locations, the anchor sleeve 104 being constituted as described in connection with FIGS. 1 7.
Referring now to FIG. I, in which the anchor assembly is shown in greater detail, it will be apparent that the reinforced concrete plate 1, the insulating layer 2 of foamed synthetic resin, and the rear reinforced plate 3 constitute a sandwich slab. The concrete plates 1 and 3 are anchored together by tubules or sleeves 4 provided at respective extremities with means for locking the sleeve to the respective concrete plates. In the embodiment illustrated in FIGS. 1 3, the lower concrete plate 3 is provided with a lattice work or mat 6' of reinforcing rod, the rod running parallel to the plane of the paper being represented at while the rods 6b run perpendicular tothe plane of the paper. The rods 60' and 6b, therefore, define a lattice work in an interstice of which the sleeve 4 is seated. The mat has an effective thickness V (FIG. 1).
The means 5 at each end of the sleeve 4 may include rows 50 and Sb of perforations which are angularly staggered and are spaced axially by a distance U V, each hole being paired with a diametrically opposite hole so that rods 7 may be passed through the holes and project laterally to engage the rods of the mats 6. The rods 7 may be lengths of reinforcing rod and project to a distance W X where X is the spacing of a rod of the mat from the tube 4. It has been found to the advantageous to have the projecting portions of the rods 7 approximate the diameter D of the tube. In practice, 0.5 D S W 5 1.5 D. The rods 7 have diameters D" which are slightly less than the diameters d of the holes 50 and 5b. A similar anchorage of the tube 4 to the upper concrete plate is provided. The sleeve 4 may have a thickness S (FIG. 3) which is less than D and a minor fraction of the diameter D of the tube, this diameter corresponding approximately to the thickness T or T of the concrete plates. In general, insulating layer 2 will have a thickness R ranging between 0.3Tand 1.5 T. The interior of the sleeve 4 is provided with a plug 8 of the foamed synthetic resin constituting the layer 2 and punched out when the tube 4 is driven into the insulat ing layer. To facilitate the punching of this plug, an edge of the tube can be chamfered.
In FIGS. 4 7, other tube structures have been illustrated and it will be understood that, in each case, the structure may be used interchangeably with the tube 4 and in the system illustrated in FIG. 8. In FIG. 4, for example, the cylindrical tube 204 is provided with formations generally represented at 205 at opposite extremities for anchoring to the concrete plates. These formations include the ports 205a and 205b as described in connection with tube 4, and crenelated extremities having tongues 2050 which may be bent outwardly as shown in dot-dash lines to engage the concrete or, as described in connection with FIG. 7, to lodge behind the mats. In the system of FIG. 5, the tube 304 has a rectangular cross-section (square) and the rows 305a and 3051) of holes permit two or more rods 307 to extend in each direction as part of the anchor means represented generally at 305. The tube 404 illustrated in FIG. 6 is of conical configuration and likewise has means 405 in the form of rows of holes for anchoring the tube in the concrete slab. In FIG. 7, there is shown a modification wherein outwardly bent tabs 505b to lie on the other side of each concrete mat. The hexagonal tube 504 of FIG. 7 is bent from sheet metal and the ends are joined at 5040.
The improvement described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the invention except as limited by the appended claims.
What is claimed is:
l. A sandwich slab comprising a pair of spaced generally parallel concrete plates, a layer of insulation sandwiched vbetween said plates; at least one tubular anchor extending through said layer of insulation and lodged at opposite extremities in said concrete plates, said tubular anchor being provided at least at one extremity lodged in a respective plate with means positively anchoring the plate thereto, said means including at least two pairs of opposing holes formed in said tubular anchor and a respective rod traversing the holes of each of said pairs and projecting transversely from the tubular anchor into the concrete of the respective plates, the pairs of holes and rods being relatively staggered angularly; and a latticework of reinforcing bars in the plate interengaging with said rods.
2. A sandwich slab comprising a pair of spaced generally parallel concrete plates, a layer of insulation sandwiched between said plates, and at least one tubular anchor extending through said layer of insulation and lodged at opposite extremities in said concrete plates, said tubular anchor being provided at each extremity lodged in a respective plate with means positively anchoring the plate thereto, said means including holes formed in said tubular anchor and a rod traversing said holes and projecting transversely from the tubular anchor into the concrete of the respective plates, each of said plates having a respective lattice-work of reinforcing bars, said rod engaging said bars, said tubular anchor being provided at each extremity with a pair of axially spaced rows of such holes and the holes of the rows of each pair being staggered angularly with respect to the holes of the other row of the respective pair, at least one such rod traversing the holes of each row and said rods lying on opposite sides of the respective latticework.
3. The slab defined in claim 2 wherein said tubular anchor has the configuration of a conic section.
4. The slab defined in claim 3 wherein said tubular anchor is conical.
5. The slab defined in claim 2 wherein said tubular anchor has a cross-section corresponding to a regular polygon.
6. The slab defined in claim 2, further comprising a plug of thermal insulation received in said tubular anchor.