US3442058A - Concrete floor construction with duct-forming voids - Google Patents

Description

I of 3 l/v VENTO/PSJ k'ermeih CJl/aslwzd 7 Sheet K. C. NASLUND ET L CONCRETE FLOOR CONSTRUCTION WITH DUCT-FORMING VOID y leonardfl, Bihlan at'ys May 6, 1969 Filed May 31,

3,442,058 CONCRETE FLOOR CONSTRUCTION WITH DUC'I'FORMING VOIDS y 1959 K. c. NASLUND ETAL Sheet Filed May 31,

I N Vf N 70/23 1761/2 CiNaslund & I'd/1. 81' [er dig/.5

1 80710 5 MZMY y 1969 K. c. NASLUND ET AL 3,442,058

CONCRETE FLOOR CONSTRUCTION WITH DUCT-FORMING VOIDS Filed May 31, 1968 Sheet 3 ors Q W T /a6 ("2 I10 16 26 e4 5- 32 26-..- g o I [N Vf/V T023 ksnnczlz 6'.Nasland a by Leonard A. Bz'klcr United States Patent U.S. Cl. 52- 221 32 Claims ABSTRACT OF THE DISCLOSURE A concrete floor construction comprising a reinforced concrete lower slab having hollow preformed cells embedded between a monolithic structure of crisscrossing concrete ribs, said cells being made of concr te, gypsum, vitrified clay or the like, said lower slab having ducts extending between said cells and embedded in said ribs for handling the flow of air, a plurality of preformed blocks or the like covering the upper side of said lower slab, each of said blocks having an upper horizontal rim portion with at least one inverted generally frusto-conical member projecting downwardly therefrom and having a flat horizontal bottom surface engaging the lower slab, each member being hollow and having a central opening therein extending downwardly to the lower slab, said blocks being made of concrete, gypsum, vitrified clay or the like, and an elevated concrete slab extending over and covering said preformed blocks, said elevated slab extending downwardly through said openings in said frusto-conical members and forming 'bonds with the lower slab, said preformed blocks forming air passages between and around said frusto-conical members.

This application is a continuation-in-part of our copending application Ser. No. 514,948, filed Dec. 20, 1965, and now abandoned.

This invention relates to the construction of reinforced concrete floors for buildings and other structures.

One object of the present invention is to provide a new and improved reinforced concrete floor construction which embodies ducts or passages for supplying or returning air in connection with the heating and cooling of the building or other structure.

A further and more specific object is to provide a concrete floor construction comprising a reinforced concrete lower slab. A plurality of preformed blocks are placed on the upper side of the lower slab, so as to cover the lower slab. Each block comprises at least one inverted, generally frusto-conical member engaging the lower slab. Each frusto-conical member is hollow and is formed with a central opening extending downwardly to the lower slab. Moreover, each frusto-conical member has a flat horizontal bottom surface which engages the lower slab. Each preformed block also has an upper horizontal rim portion of rectangular shape, such rim portion being aligned with the rim portions of the adjacent blocks. An elevated concrete slab is poured over the preformed blocks so as to cover the blocks. The elevated slab extends downwardly through the openings in the frusto-conical members so as to form bonds with the lower slab. The preformed blocks provide spaces between and around the frusto-conical members, and are effective to exclude the concrete of the elevated slab from such spaces, whereby the spaces provide passages for air or the like.

Another aspect of the present invention relates to the preformed building block as such, comprising a preformed member having a generally horizontal upper flange portion and a downwardly tapering hollow portion. The hollow portion is formed with a generally axial opening extending in a generally vertical direction. Moreover, the hollow portion has a flat horizontal bottom supporting surface, whereby the block may be supported on a concrete slab or the like.

The building block may have one or more of the downwardly tapering hollow portions projecting downwardly from the upper flange portion.

In another aspect, the present invention comprises a concrete floor construction, including a concrete slab having a plurality of hollow, generally rectangular, preformed cells embedded therein and spaced apart in the slab. A monolithic structure of crisscrossing ribs of concrete is poured between the cells. Each cell comprises upper and lower half-boxes with open ends facing each other and forming a chamber in the cell. Each half-box has a closed end wall, directed upwardly or downwardly, and a plurality of side walls projecting toward the open end of the half-box. At least some of the side walls of the half-boxes are formed with notches at the open ends of the half-boxes. Duct members are closely received in the notches so as to extend 'between the chambers in the adjacent cells, to handle a flow of air between the chambers. The duct members are embedded in the concrete ribs between the cells. This floor construction may be employed by itself, or as the lower slab in the previously described composite floor construction, in which the lower slab supports the preformed blocks and the elevated slab. In the composite floor construction, two sets of air ducts are provided in the upper and lower slabs. Thus one set of ducts may be employed for supplying air, while the other set of ducts is employed for returning the air to the central heating or air conditioning plant.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a fragmentary elevational section showing a composite floor construction to be described as an illustrative embodiment of the present invention.

FIG. 2 is a fragmentary elevational section similar to FIG. 1 and showing additional features of the floor construction.

FIG. 3 is a fragmentary diagrammatic plan view of the floor construction of FIG. 1.

FIG. 4 is an elevational view, partly in section, of one of the upper preformed blocks for the floor construction.

FIG. 5 is a plan view of the preformed block shown in FIG. 4.

FIG. 6 is a fragmentary enlarged section showing details of a joint between two of the upper preformed blocks.

FIG. 7 is a fragmentary sectional perspective similar to FIG. 6 but showing a modified joint construction.

FIG. 8 is a fragmentary elevational section showing the joint construction of FIG. 6 as incorporated into the finished floor.

FIG. 9 is a fragmentary elevational section showing a modified air terminal unit for use with the floor construction.

FIG. 10 is a fragmentary elevational section showing a baseboard type of air outlet for use with the floor construction.

As already indicated, FIG. 1 illustrates a reinforced concrete floor construction 20 which incorporates complete structural, mechanical and electrical facilities. The floor 20 is incorporated into a building or other structure 22 having columns 24 and walls 26 for supporting the concrete floor.

It will be seen that the concrete floor 20 comprises a poured concrete slab 28 with reinforcing rods, cables 3 or other members 30 embedded therein. The reinforcing members 30 are normally made of steel, but other materials of high tensile strength may be employed.

A plurality of hollow preformed cells 32 are incorporated into the concrete slab 28 to reduce the weight of the slab, while also providing ducts or conduits for carrying air, as well as openings or spaces for electrical and other facilities. The illustrated cells 32 are square, as viewed from the top, but they may be rectangular or some other suitable shape. The cells 32 preferably extend through the slab 28 for the full depth thereof, but the depth of the slab may exceed the height of the cells, in which case the slab will completely cover the cells.

As shown in FIG. 3, the cells 32 are preferably arranged in a regular rectangular pattern, so that the poured concrete slab 28 will have intersecting ribs 34 extending between the cells. The ribs 34 are arranged in a pattern resembling a rectangular grid as viewed from the top. It will be seen that certain of the reinforcing rods or other members 30 are appropriately placed in the ribs 34 so that the rectangular grid formed by the ribs is capable of providing the main structural support for the floor. The grid-like ribs 34 act as beams to support the weight of the floor as well as the load which is placed on the floor, due to use of the building.

Preferably, each of the rectangular cells 32 comprises a pair of preformed blocks or shells 36 which are stacked, one upon the other, during the construction of the floor. Each of the illustrated blocks 36 is in the form of a rectangular tray or half-box, comprising a horizontal wall 38 and a set of four side walls 40. The block is open on the side opposite from the horizontal wall 38. The blocks 36 are preferably made of precast concrete, but may also be made of gypsum, vitrified clay, or other suitable materials.

The blocks 36 are assembled with the lower block in an upright position, to open upwardly, and with the upper block in an inverted position, to open downwardly into the lower block. Thus, the horizontal wall 38 of the lower block forms the bottom wall of the cell 32. The horizontal wall 38 of the upper block forms the top wall of the cell. The side walls 40 of the superimposed blocks are aligned with one another to form the side walls of the cell 32.

In the construction of the concrete slab 28, temporary forms are built to support the slab. The pairs of blocks or half-boxes 36 are placed on the forms in the desired rectangular pattern. The reinforcing members 30 are placed above the forms. Then, concrete is poured into the forms to a depth corresponding to the total depth of the stacked blocks 36. The concrete fills the spaces between the cells 32 so as to form the ribs 34. After the concrete has hardened and cured sufficiently, the temporary forms may be removed. It will be evident that the filler blocks 36 serve as permanent forms which are incorporated into the poured concrete slab 28 to form the cells 32.

In order that the hollow cells 32 may serve as air ducts, interconnecting conduits or ducts 42 are provided between the cells. The conduits 42 may be made of sheet metal or other suitable materials. In the illustrated construction, openings 44 are formed in the side walls 40 of the blocks 36 to receive the conduits 42. The illustrated openings 44 are oval in shape but may be of any suitable shape. One half of each of the openings 44 is formed in each of the superimposed blocks 36. The openings are preferably preformed in all four sides of the blocks 36. Any of the openings which are not needed or desired may be closed by suitable panels 46 during the construction of the concrete slab 28. The panels 46 may be made of sheet metal or other suitable material.

The conduits or pipes 42 are installed between the blocks 36 as the blocks are positioned on the temporary forms during the construction of the floor. Thus, all of the conduits 42 are in place before the concrete is poured to complete the slab 28. As shown in FIG. 1, some of the cells 32 may be formed with air openings 48 for admitting or discharging air. Each opening 48 is preferably formed in the lower horizontal wall 38 of the corresponding cell 32. A grill or louver structure 50 may be mounted in or over the opening 48. The opening 48 may be preformed in the corresponding block 36, or may be cut through the horizontal wall of the block.

The hollow cells 32 may also be employed to carry other facilities such as pipes 52 for an automatic sprinkler system. As shown in FIG. 1, the pipes 52 extend through the conduits or ducts 42. Sprinkler heads 54 may be connected to the pipes 52 by means of suitable branch pipes 56. Openings 58 may be drilled or otherwise formed in the lower horizontal walls 38 of the cells 32 to accommodate the sprinkler heads 54.

The lower slab 28 may be employed by itself, in some cases, but it is preferred to employ the slab 28 to support an elevated floor structure 60 which incorporates other mechanical and electrical facilities. As shown in FIG. 1, the elevated floor structure 60 employs preformed blocks 62 which provide hollow spaces or passages 64 within the elevated floor structure. The passages 64 are preferably employed as ducts or conduits to carry air in connection with the heating or cooling of the building. Thus, the concrete floor 20 provides two sets of air passages. One set is formed by the lower cells 32 and the interconnecting ducts 42, while the other set is formed by the passages 64 in the elevated floor structure 60. It is preferred to employ the upper passages 64 to supply air to the rooms of the building, while the lower passages in the cells 32 are employed for the return flow of air. However, this situation could be reversed. During the heating season, warm air is preferably supplied through the upper passages 64 so that the upper floor structure 60 will be heated to provide a radiant heat transfer component for the rooms of the building. The heated air may also be discharged into the rooms of the building. Cool air may be supplied similarly. The preformed blocks 62 are preferably made of precast concrete, but may be made of other suitable materials, such as gypsum, vitrified clay, or the like.

As shown to particular advantage in FIGS. 4 and 5, the illustrated preformed blocks 62 comprise members 66 which are generally frusto-conical in shape but are inverted so that the passages 64 will be formed between the adjacent members. The illustrated frusto-conical members 60 are curved or arching rather than being straight in slope. Each member 66 is hollow and thus is generally in the form of an upwardly flaring tube, resembling the bell of a trumpet or flower of a morning glory. The lower end of each member 60' is circular, but the upper end forms a square or rectangular rim 68.

Each of the illustrated preformed blocks 62 is formed with two of the frusto-conical trumpet-shaped members 66. However, this situation could be varied. Thus, for example, it would be convenient in some cases to form each frusto-conical member 66 as a separate block, or to combine four of the members 66 into a single block.

The upper floor structure 60 is constructed after the lower concrete slab 28 is completed. The preformed fillers or blocks 62 are placed on the slab 28 in the desired pattern. In the illustrated construction, four of the inverted frusto-conical members 66 are placed over each of the cells 32 in the slab 28. Thus, two of the blocks 62 are placed over each cell 32, as will be evident from FIG. 3. The size of the blocks 62 corresponds to the size of the cells 32 plus the width of the concrete ribs 34 between the cells.

The rectangular rims 68 of the upper form blocks 62 are made to provide continuous coverage of the slab 28, except for the upwardly flaring openings 70 in the frusto-conical members 66. Such openings 70 extend all the way through the blocks 62. After the upper form blocks 62 are in place, concrete is poured over the blocks to form a continuous deck or floor surface 72. The concrete fills the openings 70 within the frusto-conical members 66 and comes into contact with the upper side of the lower slab 28 within each of the openings. Thus, bonds are formed between the upper slab or deck 72 and the lower slab 28 within the openings 70 in the blocks 62. In this way, the slabs 28 and 72 are securely joined to form a unitary structure.

Before the upper concrete slab 72 is poured, electrical conduits or raceways 74 and 76 may be mounted over the blocks 62. The conduit 74 may be used for power wires, while the conduit 76 may be employed for telephone or other signal wires. As shown, the conduits 74 and 76 are preferably located over the frusto-conical members 66. In this way, cross-overs between the conduits may be formed by providing offset or bent portions 78 which dip downwardly into the openings 70 within the frusto-conical members 66.

Provision should be made for all mechanical and electrical facilities, insofar as possible, before the upper concrete slab 72 is poured. Thus, branch conduits 80 may be extended downwardly from the power conduit 76 through the openings 70 in the frusto-conical members '66 to afford electrical connections for lighting fixtures 82 or other electrical units to be mounted on the underside of the lower slab 28. A suitable opening 8-4 may be drilled or otherwise formed through the upper horizontal wall 38 of the corresponding cell -32 to accommodate the branch conduit 80. A flexible conduit 86 is preferably employed between the lower end of the branch conduit 80 and the lighting fixture '82. An opening 88 may be drilled or otherwise formed in the lower horizontal wall 38 to accommodate the flexible conduit 86.

It will be evident that the opening 70 in the frustoconical members 66 of the upper form blocks 62 provide convenient access to the cells 32 of the lower slab 28. Holes may easily be drilled through the upper walls 38 of the cells to accommodate electrical conduits and other facilities, as needed.

The upper slab 72 provides a smoothly finished, continuous floor surface 90. If desired, acoustical plaster or other suitable finishing material 92 may be applied to the underside of the slab 28 to provide an attractive ceiling surface for the rooms below.

It is preferred to supply air to the passages 64 in the elevated floor structure 60 from a central source, such as a blower or fan. The air supplied to the passages 64 is normally heated during the heating season and cooled when air-conditioning is required. During the heating season, the heated air warms the upper slab 72 so that it provides a component of radiant heat transfer.

Various outlet or terminal devices may be employed for discharging the air from the passages 64 into the rooms of the building. One such terminal device 94 is illustrated in FIG. 1. The terminal device 94 is mounted above the upper slab 72 and adjacent one of the Walls 26. An opening 96 is formed in the edge portion of the upper slab 72 to provide for the flow of air from the passages 64 to the terminal device 94. It will be seen that the terminal device 94 comprises a housing 98 having openings 100 therein for discharging the air into the room. The air passes upwardly from the opening 96 and through an induction nozzle 102. into the housing 98, and then out of the housing through the openings 100. A regulating or balancing damper 104 may be provided in the housing 98 below the nozzle 102.

The terminal device 94 also includes a unit 106 for drawing air into the housing 98 from the room through openings 108. Such air is discharged from the housing 98 through the openings 100. The unit 106 is capable of heating or cooling the air drawn from the room. For this purpose, the unit 106 is connected to pipes 110 and 112 through which a heating or cooling fluid may be supplied to the unit 106. Thus, for example, hot water may be supplied to the unit .106 during the heating season, while chilled water may be supplied during the cooling season.

As already indicated, air is returned from the rooms to the interior of the cells 32 through the return air grills or louvers 50. The return air is preferably carried to the central fan or blown by the cells 32 and the interconnecting ducts 42.

Air may also be returned to the cells 32 through openings 114 in the lighting fixtures 82. The air passes upwardly into the overlying cells through openings 116 which are drilled or otherwise formed in the lower walls 38. The air passing through the lighting fixtures 82 is heated to an appreciable extent by the heat of the lamps 118. This heat passes into the cells 32 and thus is recovered by the central ventilating system.

Additional features of the floor construction are shown in FIG. 2. It will be understood that the various features are optional and may be employed as needed.

While the lighting fixture 82 of FIG. 1 is of the fluorescent type, FIG. 2 illustrates an incandescent type lighting fixture 120 which is recessed upwardly into one of the cells 32. An opening 122 is formed in the lower Wall 38 of the cell 32 to accommodate the lighting fixture 120. A flexible electrical conduit 124 is preferably employed to supply power to the fixture 120. Like the flexible conduit 86 of FIG. 1, the flexible conduit 124 is connected to one of the branch conduits 80 which comes down through the opening in one of the frusto-conical members 64. It will be seen that the flexible electrical conduit 124 extends through one of the interconnecting ducts 42 between the cells 32. The ducts 42 make it easy to install electrical fixtures or appliances in any of the cells 32, even after the entire floor has been completed. The fixture may simply be connected to the nearest branch conduit through the ducts 42.

The lighting fixture 20 may also function as a return air inlet. Thus, air may enter the fixture through the lower opening 126 therein, and may pass out of the fixture into the cell 32 through louvered openings 128 in th sides of the fixture.

Various terminal devices may be employed to supply air from the passages 64 in the elevated floor 60 to the rooms below the lower floor slab 28. FIG. 2 illustrates such a terminal unit 130, which is in the form of a hollow tubular housing extending through the entire thickness of the lower slab 28 from one of the passages 64. If desired, a variable volume damper 132 may be installed in the terminal device 130, to provide for the regulation of the amount of air supplied to the room below.

A suitable opening 134 is cut or otherwise formed in the lower wall 38 of the cell 32 to accommodate the upper end of the terminal unit 130. The opening 136 may be drilled or cut from below by working through the opening 134. Thus, additional terminal units may easily be installed after the entire floor has been completed.

FIG. 2 also illustrates another terminal unit 138 which is the same as the terminal unit 130, except that a heating device 140 is installed in the terminal unit 138, instead of the blower 132. The heating unit 140 is illustrated as being an electric heater. A flexible electrical conduit 142 is connected between the heater 140 and one of the branch conduits 80. The electric heater 140 may be thermostatically controlled to provide individual regulation of the temperature in the room below.

As illustrated in FIG. 3, the cells 32 may be made smaller in the vicinity of the column 24. Moreover, the cells 32 may be spaced apart more widely in the neighborhood of the columns 24. In this way, the amount of poured concrete is increased in the vicinity of the columns 24, so as to increase the strength of the lower slab 28. In this way, the slab is adequately strong to resist the greater shear stresses which exist around the column.

When the elevated floor structure 60 is being constructed, the preformed blocks 62 may be stabilized by employing devices therebetween for maintaining alignment between the adjacent blocks. FIG. 6 illustrates such an aligning device 144, which comprises a pair of plates 7 or washers 146 adapted to form bridges between the rim portions 68 of the adjacent blocks 62. The washers 146 engage the upper and lower sides of the rim portions 68. A bolt 148 is preferably employed to clamp the washers 146 against the rim portions 68. The bolt 148 extends through the washers 146 and through the joint between the adjacent rim portions 68. Notches 150 may be formed in the rim portions 68 to accommodate the bolt 148. A wing nut 152 is preferably provided on the bolt 148 so that it may readily be tightened against the washers 146.

FIG. 7 illustrates another aligning device 154 which may be substituted for the device of FIG. 6. The aligning device 154 is in the form of a clip which is H-shaped in cross section. Thus, the device 154 has upper and lower flanges 156 with a central web 158 extending therebetween. The flanges or plates 156 engage the upper and lower sides of the adjacent rim portions 68, while the Web 158 passes between the adjacent rim portions. The clip 154 may also be described as being I-shaped in cross section.

FIG. 9 illustrates a terminal device 160 which is similar to the terminal device 94 of FIG. 1, except that the terminal device 160 is adapted particularly for use in sChOOl buildings. Thus, the terminal device 160 employs a housing 162 which extends to a greater height than the housing 98, so that book shelves 164 may be built into the lower portion of the housing 162. The other components of the terminal device 160 are the same as illustrated in FIG. 1 and are given the same reference characters.

FIG. 10 illustrates a baseboard-type of terminal device 166, in the form of a low housing adapted to extend along one wall of the building in place of the baseboard. An opening 168 is formed in the upper slab 72 so that air may pass upwardly through the passages 64 into the terminal device 166. The air passes out of the terminal device 166 through one or more openings 170 therein. Heating or cooling coils may be provided in the housing 166, if desired.

It may be helpful to review the procedure which is employed in constructing the floor of FIG. 1. Temporary forms are erected to support the cells 32, which are placed upon the forms in a regular rectangular pattern. Each cell 32 comprises two of the preformed, pan-shaped blocks or half-boxes 36, stacked edge to edge. The reinforcing rods or members are also mounted over the temporary forms. The interconnecting ducts or conduits 42 are installed between the adjacent cells 32. Any unused openings 44 in the cells are closed by the panels 46. The sprinkler piping 52 and any similar facilities are installed in the ducts 42.

After these preparations have been made, the concrete is poured into the forms to form the slab 28, including the ribs 34 between the cells 32. The ribs 34 form a rectangular grid which provides the main structural support for the floor. The concrete is illustrated as being poured to a depth corresponding to the height of the cells 32, so that the poured concrete will be flush with the upper sides of the cells. However, the slab may be poured to a greater depth so as to cover the upper sides of the cells.

After the concrete in the slab 28 has hardened, the upper preformed blocks 62 are placed on the slab. Two of the blocks 62 are located over each cell 32. Inasmuch as each block 62 comprises two of the frusto-conical members 66, there are four of the frusto-conical members over each cell 32. The blocks 62 provide continuous coverage for the slab 28, except for the central openings in the frusto-conical members 66.

The stabilizing devices 144 may be installed between the adjacent form blocks 62, as shown in FIGS. 4, 6 and 8. Alternatively, the stabilizing or aligning devices 154 of FIG. 7 may be employed.

The electrical conduits or raceways 74 and 76 are mounted over the preformed blocks 62. Crossovers may be provided between the conduits by providing the downwardly bent portions 78 which dip into the openings in the frusto-conical members 66.

The branch electrical conduits 80 are extended downwardly from the conduits 74 through the openings 70 in the preformed blocks 62. The necessary openings 84 are drilled or otherwise formed in the upper walls 38 of the cells.

After all the desired electrical and other faciliti s are in place, concrete is poured over the preformed blocks 62 to form the upper slab 72. The concrete fills the openings 70 in the blocks 62 and forms bonds with the upper side of the lower slab 28.

After the floor has been completed, openings may be cut or otherwise formed in the lower wall 38 of the cells 32 to accommodate the lighting fixtures 82 and 120, the return air grills 50, the terminal units and 138, and any other fixtures or facilities which may be desired.

The passages 64 formed by the frusto-conical members 66 of the upper blocks 62 are preferably employed to carry air to be supplied to the rooms of the building. The air supplied to the passages 64 is heated during the heating season. In this way, the floor is heated so that it provides radiant heating. The air is discharged into the rooms by the various types of terminal units 94 (FIG. 1), 130 and 138 (FIG. 2), (FIG. 9), and 166 (FIG. 10). Inasmuch as the passages 64 extend throughout the entire elevated floor structure 60, a terminal unit may be located at any desired point above the floor, at either an exterior or an interior location. When remodelling is necessary, an opening may easily be cut through the upper slab 72 into one of the passages 64.

If it is desired to supply air to the room below, a terminal unit may be installed so as to extend through any of the cells 32. Such terminal units are illustrated in FIG. 2.

The preformed blocks 62 of the elevated floor structure 60 are positioned so that four of the frusto-conical members 66 are located in a regular pattern over each of the cells 32 in the lower slab. Thus, one of the passages 64 in the elevated floor structure 60 is disposed directly over the center of each cell 32. This arrangement is highly advantageous, because one of the terminal devices, of the type illustrated in FIG. 2, may be installed in any cell, with complete assurance that the upper end of the terminal device will have full communication with the passages 64 in the elevated floor structure.

Return air openings may be provided as needed in the lower walls of the cells. The lighting fixtures may also be constructed so as to serve as return air openings.

The passages 64 in the elevated floor structure 60 may be divided into zones or sections, if desired, by inserting panels between the preformed blocks 62 during the construction of the floor. In this way, the temperature or volume of the air supplied to the various zones may be controlled separately.

Similarly, the closure panels 46, as shown in FIG. 1, may be employed to divide the lower slab 28 into zones or sections, so that the flow of air in the various zones may be controlled separately. The panels 46 are adapted to close the openings 44 in the side walls 40 of the cells, as desired.

The floor construction has the advantage of extremely low transmission of sound, due to the provision of the upper and lower superimposed slabs, each of which comprises preformed blocks plus a large mass of poured concrete. Moreover, the fire rating of the floor constructron is high, with no need for additional fireproofing.

The concrete floor construction of the present inventron is applicable to all types of building construction. llowever, it is particularly advantageous for office buildings, other commercial buildings, schools and apartment buildings.

The upper and lower floor slabs are preferably used together, to form a composite floor structure, but they may be used separately, or in connection with other floor slab constructions.

The concrete fioor construction of the present inventron is not subject to corrosion or deterioration due to high humidity, salt air, and other factors which normally result in the rapid corrosion of ordinary steel ducts employed in conventional heating and ventilating systems. Thus, the concrete floor construction is particularly advantageous for use in the tropics, near seacoasts, and in other areas where corrosive atmospheric conditions are prevalent.

The supply and return air passages in the upper and lower slabs are large in effective cross section so that they afford ample carrying capacity for the flow of air. Thus, the power requirement for circulating the air is minimized. Accordingly, the cost of operating the circulating fans is low. Moreover, the air moves at low velocity so that a minimum of noise is produced by the ventilating system.

The floor construction of the present invention is particularly advantageous for the construction. of buildings in cold weather, because the passages in the floor may be employed immediately as heating ducts to provide temporary heat in the building. There is no need to wait for the installation of separate heating ducts.

It will be evident that the floor construction of the present invention provides all of the necessary structural, mechanical and electrical facilities which will be needed in the building. Such facilities are provided at extremely low cost, and in a manner which greatly facilitates the construction of the floor.

We claim:

1. A concrete floor construction, comprising the combination of a reinforced concrete lower slab,

a plurality of preformed blocks covering the upper side of said lower slab,

each of said blocks comprising at least one inverted generally frusto-conical member engaging the upper side of said slab,

each of said frusto-conical members being hollow and having a central opening therein extending downwardly to the upper side of said slab,

each of said frusto-conical members having a flat horizontal bottom surface engaging said slab for supporting the corresponding block,

each of said preformed blocks having an upper horizontal rim portion of rectangular shape,

said rim portion being aligned edge-to-edge with the rim portions of the adjacent preformed blocks,

and an elevated concrete slab extending over and covering said preformed blocks,

said elevated slab extending downwardly through said openings in said frusto-conical members and forming bonds with said lower slab,

said preformed blocks having spaces between and around said frusto-conical members and being effective to exclude the elevated concrete slab from said spaces whereby said spaces provide passages for air or the like.

2. A concrete floor construction according to claim 1,

in which each of said preformed blocks comprises only one of said frusto-conical members.

3. A concrete floor construction according to claim 1,

in which each of said preformed blocks comprises a pair of said inverted frusto-conical members.

4. A concrete floor construction according to claim 1,

in which electrical conduits are embedded in said upper elevated concrete slab above said preformed blocks, and in which at least two of said conduits cross each other,

one of such crossing conduits having a downwardly olfset portion which dips downwardly into one of said openings in said inverted frusto-conical members at the cross-over point with the other crossing conduit.

5. A concrete floor construction according to claim 1,

comprising a terminal device disposed above said elevated concrete slab and having an outlet opening for discharging air or the like,

said elevated slab having a connecting opening extending upwardly therein from said passages in said elevated slab for connecting said passages to said terminal device.

6. A concrete floor construction according to claim 1,

including a plurality of aligning devices connected between the rim portions of the adjacent preformed blocks for aligning and stabilizing said blocks.

7. A concrete floor construction according to claim 1,

in which a plurality of aligning devices are connected between said rim portions of the adjacent preformed blocks for maintaining said rim portions in alignment,

each of said aligning devices comprising upper and lower washers engaging the upper and lower sides of, said rim portions,

and a bolt extending through said washers and be tween said rim portions for clamping said washers against said rim portions.

8. A concrete floor construction according to claim 1,

in which said lower slab comprises a plurality of hollow preformed cells embedded therein,

said cells being spaced apart in said lower slab with concrete supporting ribs disposed between said cells,

each of said cells having an upper wall flush with the upper side of said lower slab,

said bottom surfaces of said inverted frusto-conical members being supported directly on said upper walls of said cells,

said bonds with said elevated slab being formed with said upper walls of said cells.

9. A concrete floor construction according to claim 8,

comprising a main electrical conduit embedded in said elevated slab above said preformed blocks,

a branch electrical conduit connected to said main conduit .and extending downwardly through one of said openings in said inverted frusto-conical members and through said upper wall of one of said cells into the corresponding cell,

and an electrical device mounted on said cell and connected to said branch electrical conduit,

said upper wall of said cell being formed with an opening to accommodate said branch electrical conduit.

10. A concrete floor construction according to claim 8,

comprising a terminal conduit extending through said lower slab from one of said passages in said elevvated slab,

said terminal conduit extending through one of said cells,

said upper wall of the corresponding cell being formed with an opening to accommodate said terminal conduit.

11. A concrete floor construction according to claim 10,

in which said cell has a lower wall formed with another opening to accommodate the lower portion of said terminal conduit.

12. A concrete floor construction according to claim 8,

in which a plurality of ducts are connected between the adjacent cells and are embedded in said lower slab for the passage of air or the like through said cells.

13. A concrete floor construction according to claim 12,

in which at least one of said cells is formed with a bottom wall having an opening extending therethrough for the passage of air or the like.

14. A concrete floor construction according to claim 8,

in which four of said inverted frusto-conical members of said preformed blocks are positioned over each of said cells in said lower slab.

15. A concrete floor construction according to claim 1,

in which said concrete lower slab comprises a plurality of hollow generally rectangular preformed cells embedded in said lower slab,

said cells being spaced apart in said? lower slab,

said lower slab comprising a monolithric structure of crisscrossing ribs of concrete disposed between said cells,

each of said cells comprising upper and lower halfboxes with open ends facing each other and forming a chamber in said cells, each of said half-boxes having a closed end wall and a plurality of side walls projecting therefrom toward the open end of said half-boxes, at least some of said side walls of said half-boxes being formed with notches at the open ends of said halfboxes, and duct members closely received in said notches and extending between said chambers in adjacent cells to handle a flow of air between said chambers, said duct members being embedded in said concrete ribs between said cells. 16. A concrete floor construction according to claim 1, in which said preformed blocks are made of precast concrete. 17. A concrete floor construction according to claim 1, in which said preformed blocks are made of gypsum. 18. A building block, comprising a preformed member having a generally horizontal upper flange portion and a downwardly tapering hollow portion projecting downwardly therefrom, said hollow portion having a generally axial opening extending therethrough generally in a vertical direction, said hollow portion having a lower end portion with a flat horizontal bottom supporting surface thereon. 19. A building block according to claim 18, in which said hollow portion is generally of an inverted frusto-conical shape. 20. A building block according to claim 18, in which said outwardly projecting generally horizontal flange portion is of substantially rectangular shape. 21. A building block according to claim 18, in which said hollow portion is of an inverted frustoconical shape, and in which said outwardly projecting generally horizontal flange portion is of generally rectangular shape. 22. A building block according to claim 18, made of precast concrete.

23. A building block according to claim 18, made of gypsum.

24. A building block according to claim 18, made of vitrified clay.

25. A building block, comprising a preformed member having a generally horizontal upper flange portion with a pair of downwardly tapering portions projecting downwardly therefrom, each of said downwardly tapering portions being hollow and having an axial opening extending therethrough generally in a vertical direction, each of said downwardly tapering portions having a flat horizontal bottom supporting surface thereon. 26. A block according to claim 25,

in which each of said downwardly tapering portions is of a generally inverted frusto-conical shape.

27. A block according to claim 25,

in which said flange portion is generally rectangular in shape.

28. A concrete floor construction,

comprising a concrete slab having a plurality of hollow generally rectangular preformed cells embedded therein,

said cells being spaced apart in said slab,

said slab comprising a monolithic structure of crisscrossing ribs of concrete disposed between said cells,

each of said cells comprising upper and lower halfboxes with open ends facing each other and forming a chamber in said cell,

each of said half-boxes having a closed end wall and a plurality of side walls projecting therefrom toward the open end of said half-box,

at least some of said side walls of said half-boxes being formed with notches at the open ends of said half-boxes,

and duct members closely received in said notches and extending between said chambers in the adjacent cells to handle a flow of air between said chambers,

said duct members being embedded in said concrete ribs between said cells.

29. A concrete floor construction according to claim 28,

in which said duct members are oval in cross section,

and said notches are of corresponding semioval shape.

30. A concrete floor construction according to claim 28,

in which said cells are made of precast concrete.

31. A concrete floor construction according to claim 28,

in which said cells are made of gypsum.

32. A concrete floor construction according to claim 28,

in which said cells are made of vitrified clay.

References Cited UNITED STATES PATENTS 1,995,393 3/1935 Manske 52344 2,089,893 8/1937 Greulich 52-221 2,107,523 2/1938 Coe 52-380 2,294,554 9/1942 Henderson 52-221 2,729,429 1/ 1956 Goemann 49 2,741,117 4/1956 Hoseason 52-221 2,811,850 11/1957 Clary 52--220 FOREIGN PATENTS 26,664 1954 Finland.

1,245,853 1960 France.

996,805 6/ 1965 Great Britain.

FRANK L. ABBOTT, Primary Examiner.

PRICE C. FAW, IR., Assistant Examiner.

US. Cl. X.R.

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