US3888447A

US3888447A - Scaffolding for supporting fresh concrete floor slabs

Info

Publication number: US3888447A
Application number: US443090A
Authority: US
Inventors: Yakichi Tsushima
Original assignee: Nisshin Tsushima Co Ltd
Current assignee: Nisshin Tsushima Co Ltd
Priority date: 1974-02-15
Filing date: 1974-02-15
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10

Abstract

This invention provides a temporary structure of triangular shape for supporting a concrete floor slab until the concrete in the slab is solidified, wherein the structures are simply suspended between adjacent beams, being positioned above the ground, thereby providing a spacious work space thereunder.

Description

United States Patent Tsushima June 10, 1975 [541 SCAFFOLDING FOR SUPPORTING FRESH 3,035.805 5/1962 Blank 248/354 P CONCRETE FLOOR SLABS 3.l65.288 l/l965 Jackson 1 A 248/235 X 3.I70.2l7 2/l965 Williams 249/2l9 R X (75] Inventor: Yakichl Tsushima. Nagoya. Japan 3.441084 5/1969 Williams 249/219 R X t 3.738.602 6/1973 Arnett 248/235 X [731 Assignees: Nlsshm Tsushlma (50., Ltd., Nagoya. s

c tani & Co" Ltd" Osaka 3.78 .109 l/l974 Letourneur 52/690 X both of Japan; a part interest to FOREIGN PATENTS OR APPLICATIONS each 173,953 2/1905 Germany 249/219 R F 5, Italy 1 R [211 Appl' 443090 Primary Examiner-J. Franklin Foss Attorney. Agent, or FirmBacon & Thomas [52] US. Cl 248/235; 52/691; 249/219 R [51] Int. Cl....... E04g 3/00; E04b 1/18; EO4g 11/50 [57] ABSTRACT [58] Field of Search 248/235; 249/219 209; This invention provides a temporary structure of triangular shape for supportmg a concrete floor slab until the concrete in the slab is solidified, wherein the [56] References Cited structures are simply suspended between ad acent UNITED STATES PATENTS beams, being positioned above the ground. thereby 492.748 2/1893 Pickles 52/692 providing a spacious work space thereunder. 2.168.991 8/1939 Hungcrfortlm. 249/219 R x i 2.613.904 10/1952 Sum 245/354 P 5 Clams, 7 Drawing Flgul'es PATENTEDJUH 10 ms SHEET Flq.

1 SCAFFOLDING FOR SUPPORTING FRESH CONCRETE FLOOR SLABS BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to a scaffolding for supporting forms for concrete floor slabs, to be used in constructing a concrete building. More particularly. the invention relates to a truss-like scaffolding for temporary support of a floor slab until the concrete of the slab is solidified.

Temporary support for forming concrete floor slabs are well known in the art and consist essentially of a strut adjustable in height by an adjusting screw provided in the middle thereof. This type of strut is usually provided in numbers between an individual joist and the floor, and accordingly a great number of struts are necessarily used on one floor. The disadvantages of this known strut are as follows:

I. The strut presupposes that the lower floor is sufficiently solidified. This requires that each floor slab be finished in order from the ground floor to a higher floor. Even in this case. a certain period of time must be interposed before the concrete in the slab becomes solid. Until then, the subsequent procedure cannot be initiated. This tends to prolong the time of construction.

2. The strut is supported between the lower floor and an individual joist by a point-to-point contact, and, therefore, a great number of struts are needed for one floor, thereby resulting in the increased labor and loss of efficiency.

3. When the floor is to be levelled, it is necessary that the individual struts be regulated in height. This tends to cause difficulties and consume time.

4. The room under the slab is filled with a number of, or forest" of struts, so that it cannot be used as a working space.

In conclusion, in using a conventional strut system the time consumed in construction is prolonged, and the procedure is complicated, which all reflect upon the cost of construction.

The present invention is directed to improvements in the temporary support of forms for a concrete floor slab, and has as one of its objects to provide a device which makes it possible to fabricate concrete floor slabs on each floor at the same time. Another object is to provide a device which, during operation, leaves a sufficient spacious working space thereunder. A further object is to provide a device which can be applied at varying distances between beams. Another object is to provide a device capable of ready assembly and disassembly without the use of special skill and tools. Other objects and advantages will become apparent as the description of the invention proceeds; it should be understood, however, that the detailed description and a specific example are given by way of illustration only, since various changes and modifications within the spirit of the invention will become apparent to those skilled in the art from this detailed description.

The scaffolding of this invention comprises a triangular structure consisting of a main chord and a pair of lower chords; at least one bracing means connected in the joint of said lower chords; and a means for temporarily sustaining said structure between adjacent beams.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the detailed description given hereinafter and the drawings which are presented by way of illustration only, and thus are not limitative of the present invention and wherein:

FIG. 1 is a front view of a scaffolding for supporting a concrete floor slab, according to the present inventron;

FIG. 2 is a perspective exploded view of the parts of the scaffolding illustrated in FIG. 1;

FIG. 3 is a perspective exploded view of the fastening device to be used in the scaffolding illustrated in FIG.

FIG. 4 is a perspective exploded view of the jointing device connecting the two lower chord members;

FIG. 5 is a perspective view of the bracket for sustaining the scaffolding to the side of a beam;

FIG. 6 is a perspective view of the supporting element for the bracket illustrated in FIG. 5', and

FIG. 7 is a schematic view of the scaffolding in actual use for sustaining a form for a concrete floor slab.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As clearly illustrated in FIG. 1, the scaffolding of this invention is constructed in the form of a triangular truss, consisting essentially of a main chord l1 and two lower chords 13, between which there is at least one brace 12 (in the illustration, two bracings are used). Each chord and the braces are respectively connected by means of fastening devices 14a to 14d of the same construction. The main chord 11 is provided with a bracket 15 at opposite ends, which brackets are supported by supporting elements 16 in the manner as described hereinbelow.

Referring to FIG. 2, the main chord 11 is made up of two members, i.e., the left-hand member 17 and the right-hand member 18, each being made of an angle iron, wherein the reference numeral 19 indicates the horizontal side, whereas the reference numeral 20 indicates the vertical side in which apertures 2I are spaced for receiving locking pins 22. The two

members

17 and 18 are also joined by the fastening

devices

14a and 14b where they are overlapped.

As best illustrated in FIG. 3, the fastening devices 14a to 14d are individually made up of a wedge member 23 and a locking pin 22. The pin shank 24 has a pair of grooves 25 obliquely produced in parallel on opposite sides thereof. The wedge member 23 is made of a plate 26 having its central portion 27 defining a sloping surface in which there is provided hole 28 and a lengthwise slot 29, which allows the rims of the slot 29 to fit into the grooves 25 when the wedge member is driven by blows upon the tail portion 230 thereof by a hammer. Thus the locking pin 22 is securely wedged in the lengthwise slot of the wedge member 23.

As is apparent from the foregoing, the left-hand and right-

hand chord members

17 and 18 are partially overlapped with at least one aperture 21 in each member being aligned with each other, wherein the selection of the aperture will be made to determine the desired total length of the main chord 11. Subsequently, the wedge member 23 is placed against the vertical side of the

members

17 or 18, and then the pin shank 24 is passed through the

apertures

21 and 28. When it is sufficiently protruded from the aperture 28 in the wedge member, blows are struck upon the tail portion 23a, e.g., by a hammer. Thus, the pin shank 24 is tensioned and held fast in the lengthwise slot 29, thereby interlocking the left hand and right-hand members I7 and 18 to form a single main chord. The fastening devices 140 to 14d are used in the same manner.

As illustrated in FIG. 2, each brace 12 is made of an angle iron bar, provided with an aperture 30 at its upper end and with a series of apertures 31 at its lower end. Each brace 12 is secured to the main chord l1 and the lower chords 13 by the fastening devices 14b and 14d; in the preferred embodiment illustrated, the braces 12 are secured to chord 11 at points spaced apart about one third the length of chord 11.

Each lower chord 13 consists of two members. i.e., an upper member 32 and a lower member 33. The two

members

32 and 33 are joined together by an interme diate element 39 interposed therebetween, which has

threads

37 and 38 of opposite hand at its opposite ends. The

threads

37 and 38 are respectively intended to engage with the internal threads 42 of the bolt heads 41. The threaded legs 43 of each bolt 40 are oppositely directed towards the respective

lower chord members

32 and 33, and each bolt 40 is tightened up by companion nuts 44. The intermediate element 39 includes flattened portions 36 in the central shank, which are oriented 90 apart so as to provide a base for a hand tool. When the intermediate element 39 is rotated by the hand tool, the lower chord 13 is subjected to contraction or extension in accordance with the direction of rotation thereof, whereby the main chord as a whole is bent upwardly or downwardly. Each lower chord I3 is joined to the main chord 11 by means of the fastening devices 14c in the same manner as described above, wherein the

apertures

45 and 46 in each chord 11 and 13 are aligned to accept a locking pin, whereas the two lower chords per se are mutually joined by means of the fastening device 14d, with the braces 12 interposed therebetween. In this case, one aperture 46 will be selected from the group of them to determine the desired total length of the lower chord 13.

Referring to FIGS. 2 and 5, the bracket is made of molded plastic, and consists of a box-shaped main body 47 and a tail portion 48 in which an aperture 49 is made by which the bracket may be attached to the main chord 11. In FIG. 5, the upper surface 50 is intended to receive the horizontal side 19 of the main chord l1 and the opposite lower surface 51 is provided with a key 52 located adjacent to the outer edge thereof, which key is dimensioned to fit into the corresponding opening 60 in the mating supporting element 16, which will be described hereinbelow. The brackets 15 are secured to the opposite ends of the main chord 11, with their tail portions 48 being extended alongside of the vertical side of the main chord 11, wherein the braces 12 are additionally secured to the main chord by means of the fastening device 14c as illustrated in FIG. 2.

Referring to FIG. 6, the supporting element 16 is mainly made of a channel post 53, in which there is provided a pivotal plate 54 having a pivot 56. The pivotal plate 54 is normally sustained horizontal by a stop plate 59, which is removably inserted through openings 57 and 58, in order to prevent accidental loss of plate 59, the stop plate may be tied by a string or chain fastened to the body of the channel post 53. The pivotal plate 54 is provided with the opening 60 in the center for accepting the key 52 on the bracket 15 referred to above. Under the openings 57 and 58, there are provided further openings 6] for allowing a rod to pass through, the rod serving as the second stop against the bracket 15, which will be described hereinbelow. The channel post 53 has four apertures 62 at the back thereof to provide for attaching the post 53 to a supporting beam or the like.

The operation of the scaffolding thus described is as follows:

As illustrated in FIG. 7, the supporting elements 16 are initially secured to the inside wall 630 of a veneer formwork 63 covering the beam 65, by means of bolts and nuts. The supporting elements 16 are spaced as desired. The formwork 63 covers the beam 65 from below, and is supported by a standard 69.

As is evident from the foregoing, the scaffolding of this invention is readily adjustable to the distances between the opposing inside walls 630 of the formworks 63. Preferably, the main chord 11 is bent upwardly sufficiently to define an arch, so as to flex to level when a high load is exerted thereupon by the concrete slab 68. This is accomplished by rotating the intermediate element 39 by a spanner. As it is rotated, each brace 12 is raised, thereby pushing the main chord 11 upwards at the respective joints of the bracings. Thus, the upward bending of the main chord is brought about.

An appropriate number of scaffoldings thus prepared are secured in parallel between the adjacent formworks 63a by means of the supporting elements 16, wherein, as described above, the keys 52 on the brackets 15 are respectively fitted into the corresponding openings 60 in the supporting elements 16, thereby ensuring the engagement of the two

members

15 and 16.

After the scaffoldings 10 are suspended in this way, joists 66 are crosswisely placed thereon at desired intervals. Subsequently, the form 67 for floor slab 68 is placed on the joists 66. Finally, concrete is poured into the

formworks

63 and 67. Obviously, the series of steps described above can be simultaneously done on each floor, which is different from the prior art.

When the concrete is sufficiently solidified, the

formworks

63 and 67 are removed in the following manner:

The scaffoldings 10 are removed, except those located at opposite extreme ends of the joists 66. In this case, the stop plates 59 in the supporting elements 16 are respectively taken away, e.g., by hitting same by a hammer, thereby allowing the pivotal plate 54 to rotate downwards around the pivot 56. No more support for the brackets 15 is provided by the supporting elements 16, whereby the individual scaffolding 10 as a whole is readily removed from the supporting elements 16. In the case of the remaining scaffoldings, however, a different procedure is followed: initially, a suitable rod or bar is temporarily held through the openings 61. Then the stop plates 54 are taken away in the same manner as above. But the rod functions as a second stop for the bracket 15, thereby retaining the scaffoldings and the joists 66 slightly spaced from the underface of the concrete floor slab 68. In this situation, the remaining scaffoldings and the joists 66 become ready for removal.

When the scaffolding 10 is set free from the high tension given by the concrete slab, the main chord 11 restores to its original state of arch shape. Accordingly, when constructing a high concrete building, the scaffoldings can be successively used as they are, from one floor to another, without the need for renewed adjustment particularly of the main chord. which has already been preset on a lower floor.

The scaffolding can be readily disassembled into portable pieces by reversing the assembly procedures described above,

When the total length of the main chord 11 is to be changed, the intermediate elements 39 are initially loosened to relax each joint among the chord members and the bracings. Then the

fastening devices

14a, 14b and 14d, and the bolts 40 are removed, thereby allowing the left-hand and right hand chord members to shift for adjustment. After adjustment is thus made, the loosened members are tightened, and the removed members are joined again in the manner as described above.

According to the present invention, it will be appreciated that the time for construction is immensely reduced by virtue of simultaneous fabrication of floor slabs on each floor, and in addition, the preparatory procedures are largely simplified in forming individual concrete floor slabs, thereby resulting in reduced labor cost.

What is claimed is:

1. A scaffolding for temporary support ofa fresh concrete floor slab, comprising means defining a main chord member disposed substantially horizontally and a pair of lower chord members detachably joined together at adjacent ends, the free ends of said lower chord members being respectively detachably joined to said main chord member to define a triangular structure, and at least one bracing member detachably fastened at the joint between lower chord members, the free end of said bracing being detachably joined to said main chord member, said main chord member and the lower chord members each respectively consisting of two separate members which are overlappingly joined together so as to form a single chord, the two members of each lower chord being overlappingly joined together with an intermediate element interposed therebetween, said intermediate element including opposedly wound threads at opposite ends, each member being connected to said intermediate element through a screw means such that when said intermediate element is rotated said chord members are relatively moved to change the lengths of said lower chord members.

2. A scaffolding as claimed in claim 1, wherein each of the separate chord members includes a series of openings spaced lengthwise thereof, two openings selected from each group in overlapping members being aligned so as to allow a locking means to pass through.

3. A scaffolding as claimed in claim 1, wherein two braces are used, each being joined to said main chord at points spaced apart about one-third of the length of said main chord member.

4. A scaffolding as claimed in claim 1, wherein the joints between the main chord member, the lower chord members and the bracing are each secured by a fastening means comprising a wedge means for a locking means, said wedge means being adapted to be driven by percussion blows so as to fasten said locking means.

5. A scaffolding as claimed in claim 1, wherein the triangular structure is supported between adjacent beams by means of a supporting unit, which comprises a bracket secured to said main chord member and a supporting element secured to the beam side, said bracket being detachably supported by said supporting element.

Claims

1. A scaffolding for temporary support of a fresh concrete floor slab, comprising means defining a main chord member disposed substantialLy horizontally and a pair of lower chord members detachably joined together at adjacent ends, the free ends of said lower chord members being respectively detachably joined to said main chord member to define a triangular structure, and at least one bracing member detachably fastened at the joint between lower chord members, the free end of said bracing being detachably joined to said main chord member, said main chord member and the lower chord members each respectively consisting of two separate members which are overlappingly joined together so as to form a single chord, the two members of each lower chord being overlappingly joined together with an intermediate element interposed therebetween, said intermediate element including opposedly wound threads at opposite ends, each member being connected to said intermediate element through a screw means such that when said intermediate element is rotated said chord members are relatively moved to change the lengths of said lower chord members.