US3405903A

US3405903A - Form structure for roof slab and truss

Info

Publication number: US3405903A
Application number: US580926A
Authority: US
Inventors: Jack E Sullivan
Original assignee: FUTURA ROOFS Inc
Current assignee: FUTURA ROOFS Inc
Priority date: 1966-09-21
Filing date: 1966-09-21
Publication date: 1968-10-15
Anticipated expiration: 1985-10-15

Description

Oct. 15, 1968 J. E. SULLIVAN FORM STRUCTURE FOR ROOF SLAB AND TRUSS Filed Sept. 21. 1966 INVENTQR Jack E. Sulhvan 3,405,903 FGRM STRUCTURE FUR RQOF SLAB AND TRUSS Jack E. Suilivan, Margate, Fla, assignor, by mesne assignments, to Future Roofs, Irma, Mai-gate, Fla.

Filed Sept. 21, 1966, Ser. No. 580,926 12 Claims. (Cl. 249-28) ABSTRACT 015 THE DISCL-GSURE A form structure for the pouring of a concrete roof in which spaced parallel beams are extended between spaced building walls at a common level approximating their tops. These beams provide temporary supports on each of which are removably rested double sets of vertical form walls arranged end to end to extend lengthwise of the beam with opposite end portions of the form walls lapping over the tops of the building walls. Spacer means are also removably carried by the beams to fix the positions of the vertical for-m walls, top and bottom. Decking boards are removably carried by certain of the spacer means adjacent the tops of the vertical form walls. All of the form walls, spacer means, and decking boards are interfitted for fixed mutual bracing without extraneous fastening means therefor. The resulting form structure is open only at the tops of each set of double vertical form walls to permit concrete, when poured therethrough, to fill all spaces therebetween and, when spread over the decking boards, to provide thereon a continuous slab which is integral with supporting trusses which are molded between each set of double vertical form walls. These trusses in their end portions overlie the tops of the building walls to be permanently supported thereby. Dismantling of the form structure, when the concrete is set, is accomplished by removal of its components in an order which is the reverse of that followed during erection thereof, the underlying beams being the last to be taken down.

This invention relates to a building roof of monolithic construction, and more particularly to the form structure used in its production. The exemplification herein illustrated and described is designed particularly for saddle roofs having a ridge, such as are commonly found in residences and small buildings.

It is a primary object of this invention to provide an all-concrete roof having the unique advantages of a stable anchorage, long life, low maintenance, low thermal conductivity, and incombustibility; to provide for such a roof a set of production for ms adapted for repeated use with buildings differing widely in size and plan; to utilize form components of minimum number which are adapted for crane-free storage, transportation, assembly, disassembly, and facile handling in general; and to design form components which will readily interfit and support each other when assembled in operative position on the job, all with a minimum of time, effort and appurtenances. The roof structure so provided is supported upon spaced trusses or girders (hereinafter referred to generally as trusses) which rest upon the building Walls, such trusses being provided therethrough with access openings suitable to to receive air ducts, electrical conduits, etc. In a subsequent single operation of pouring, these trusses are joined integrally to each other, and to a top slab of concrete or the like, the latter then becoming a compression member forming a top chord of the truss-roof structure in its entirety.

An all-concrete roof of this general description is adapted for production on erected building walls in the position which it is to permanently occupy, this also be- United States Patent 0 3,405,903 Patented Oct. 15, 1968 ing a primary object of my invention. In practice, the forms and other appurtenances are delivered to the job where they are assembled for subsequent production of a plurality of all-concrete trusses extending in parallelism between opposite building walls to be supported thereby in fixed vertical positions. Concrete in a plastic state is then poured into the forms to occupy all the spaces therewithin and, with continued pouring, to be spread oper a roof decking therebetween thereby in a single pouring operation to provide a continuously extending slab which is integrally joined to all trusses. This operation of pouring the concrete may be performed expeditiously, usually requiring less than half a day altogether. When set, the forms are dismantled and loaded on to trucks to be removed to a central storage place, all without crane service. If and when required for use on another job, the building plans therefor are examined to ascertain the building size, the spaces between walls, etc., and form components suitable for use therewith are then selected for delivery to the site. An experienced crew which later follows will assemble and erect the forms in the correct positions for the subsequent operation of concrete pouring. By this method of procedure, considerable time, effort and cost is saved.

Another major objective attained by this invention is the production, in a single concrete pouring operation on the job, of -a plurality of supporting trusses together with a roof slab thereover, all integrally interconnected into a unitary structure. This is accomplished by use of interfitting for-m components and supporting means therefor of such size and weight as to facilitate their handling, erection and subsequent dismantling all by hand and without crane assistance. No fastening elements, such as nails to be driven into or through the fonm components, need be used in the completed form structure. Furthermore, most of such components and appurtenances are relatively flat and free of lateral projections so as to stack more readily and compactly into a storage space or upon a flatbed truck when being transported to or from a job site. As part of the completed form structure, I utilize a ground which is horizontally disposed and so located as to underlie each truss, when poured, whereby optionally to constitute a bottom for the truss. If desired, the ground may be provided with means to remain permanently assembled therewith so as to serve as a supporting medium for a room ceiling subsequently constructed within the building.

These and other objects of the present invention may be successfully embodied in a structure such as is herein described and illustrated in the accompanying drawing in the manner following:

FIGURE 1 is a fragmentary cross-sectional view, taken on line 11 of FIG. 3, showing a freshly poured roof slab and portions of one concrete truss as they appear when only the form structure for the eaves has been dismantled;

FIG. 2 is a similar cross section, but fragmentary and on an enlarged scale to show additionally a portion of the form structure for one of the caves and portions of the completed truss which are exposed by removal of one set of the form walls therefor;

FIG. 3 is a fragmentary transverse sectional view, taken on line 3-3 of FIG. 1;

FIG. 4 is an enlarged detail in section, taken on line 4-4 of FIG. 1;

FIG. 5 is a perspective view of one of the knock-down stands;

FIG. 6 is an elevational view of one of the relatively short wire clips to be used as a top spacer between the two form walls of one of the trusses; and

FIG. 7 which is a similar view shows one of the relaused as a top spacer between tively long wire clips to be confronting form Walls of 'two adjacent trusses.

As herein shown, the present all-concrete roof structure comprises a plurality of parallel trusses, spaced apart at fixed distances, each having an end portion resting upon the top of a building side wall X which may be made up of concrete blocks or the like. When so positioned, each concrete truss will extend over the span between a pair of such walls to provide support for a concrete roof slab S which is integrally united with each truss and with eaves E projecting outwardly beyond the building side walls. The general form of each truss is that of a triangle having a long horizontal base extending between the outer ends of a rafter-like body which rises to the ridge line of the roof. A truss of this description will then conform in size and shape with gables rising from end walls Y of the same building at opposite ends of the ridge line, the tops of these gables then terminating in planes slightly below the under face of the roof slab, when completed (FIG. 3). The terms side and end for the building walls have been chosen primarily for convenience herein, although otherwise not necessarily apt in meaning.

The form structure for such a truss is a major feature of this invention. It comprises a plurality of like structures each carried upon a truss beam B of channel iron or the like, having a length slightly less than the distance separating two opposite side walls X. The flanges of each truss beam extend downwardly to rest upon certain cross rails R which provide support for all the beams thereover, the number of such rails being at least two, and probably more depending upon the length of the trusses to be formed thereover. Each rail is desirably made up of wooden boards, each about 2 by 8 inches in cross section, assembled end to end and staggered in double rows, on opposite sides of a metal plate (or plates), the several boards so arranged being suitably united, as by bolts, to provide a strong sturdy rail. The rail components may be so assembled as to provide an overall length therefor which will present its ends substantially at the opposite end walls Y of the building when supported therein at a level slightly below the gables which rise from such walls. Each rail is rested at spaced intervals along its length upon the heads 10 of adjustable jacks I which are vertically disposed with their feet 11 rested upon the floor F, or other solid base. The jacks are properly adjusted to support the top faces of the beams B, when rested upon the rails, at substantially the level of the tops of the building side walls X whereon the trusses are to be erected.

Each truss beam B, if its length so requires, may consist of several sections arranged end to end with rail supports R provided therefor, as needed. It is comparatively light in weight and may be readily handled by one or two men. Because of its channeled cross-section, it will sustain without sagging a considerable load between its points of spaced support from the cross rails therebelow. A beam width of 6" or so is desirable, enabling it to receive upon its top face a ground G extending for the full distance between the building side walls X. This ground may conveniently consist of a 2" by 4" wooden piece, or several such pieces arranged end to end. When properly positioned, the ground is centrally disposed along the top of the truss beam B so as to leave along its edges unoccupied portions each constituting a ledge having a width of slightly more than 1''. Upon these ledges are rested thebottom edges of vertical form boards which are elongated horizontally and arranged end to end in abutting relation so as to extend through a distance equal to the space between the building side walls X. If produced from plywood which is commonly made in only relatively short lengths, three or more of these vertical form boards are combined into a single set. The horizontal length of each board is a maximum of 8 feet, so that for relatively short spans up to perhaps 24 feet, three boards will sufterminate in a vertical plane approximately the same as that of the inner face of the proximate side wall X. Between the two outer boards 0 is fitted the middle board M havin its bottom edge rested upon the beam ledge with opposite ends upstanding vertically to join with oppositely inclined top edges each of which is in alignment with the hypotenuse of the proximate outer board 0. It will be found convenient to use for these vertical boards M and 0 plywood having a thickness of approximately Two sets of these vertical boards are required for each beam, to be set up along opposite sides of the ground G which then serves to space them uniformly apart along their bottom portions. This same spacing is maintained at the tops of the vertical boards M and O as by means of short stout-wire clips 15 (FIGS. 4 and 6), spaced apart at intervals of two feet or so, each bent to provide two like channels for reception of a top edge portion of each board to which the clip is applied.

The two sets of vertical boards M and 0 provide form walls of the requisite spacing for reception of concrete which may be poured thereinto from the open top which extends continuously for the full length of the truss which is to be formed between them. Special means to prevent spreading of these vertical form walls is also provided, as will hereafter be noted. It is desirable that the truss produced from the form structure under description should also be provided with access openings 0 therethrough, to reduce weight by elimination of concrete where not necessary, and to provide for installation therethrough of conduits, cables, etc., also to enable workmen whose duties so require to move freely between the spaces defined by the several roof-supporting trusses in the completed building. A convenient arrangement of two such openings is on opposite sides of a vertical line intersecting the highest point of the truss where maximum space for this purpose is available. The form of the access openings 0, as herein shown, is triangular with each opening having a vertical side spaced from the other to leave therebetween a vertically extending king post 17. Two triangular cores 18 are provided to assure the forming of such access openings, and for this purpose one of the middle form boards M carries three cleats 19 which are so disposed as to engage inner faces of the triangular core and provide a fixed support therefor when the latter is fitted thereupon. The width of this core is such as to extend the full distance between the confronting faces of the opposing form boards M so that concrete, when poured to fill the space between the erected form walls, will be prevented from entering the triangular spaces defined by the two triangular cores so placed. After the concrete has set, and dismantling of the form structure is under way, these triangular cores may be removed for subsequent use elsewhere.

The vertical form boards M and O are removably secured adjacent the ground G by elongated base spacer boards H each of which is horizontally extended between two adjacent beams B. Plywoodhaving a thickness of about /3" may be used advantageously for these boards. A width of about two feet for each such spacer board is also advantageous, and with the beams B desirably spaced for reception of the base spacer boards therebetween, the longitudinal edge portions of the latter will then rest'upon the unoccupied ledges of the beams and in so doing will engage the vertical form boards M and O to maintain their bottom edge portions engaged with the ground G. Several such base spacer boards, each disposed lengthwise within the space between adjacent form structures on the beams, may be required to provide the necessary bracing between the vertical form boards at points, continuously or otherwise, between opposite ends of the trusses under construc tion. It is not necessary that these base spacer boards be arranged end to end with no gaps therebetween; limited spaces may be left between them, particularly if their combined length be shorter than the span between the building side walls X, or they may be slightly overlapped wherever necessary or convenient if their combined length would otherwise exceed such span.

The base spacer boards provide, in effect, a platform upon which may be rested certain knockdown stands K. These stands are conveniently produced from two duplicate plywood boards and 21, each about 12" by 22" with an open ended slot 22 extending transversely thereof for one half its width at a mid point lengthwise thereof (FIG. 5). Each such board may then be interfitted with the other to lie transversely thereof to occupy a standing position with coplanar top and bottom edges each disposed in the form of a cross. Two or more such stands may be placed at spaced points upon the base spacer boards H with either

board

20 or 21 extended crosswise of the space between two adjacent pairs of form walls M. The purpose of these stands is to furnish spaced supports for one or more intermediate spacer boards I extending horizontally above the base spacer boards at a higher level of a foot or so. The width of the intermediate spacer boards I is the same as that of the base boards H whereby the adjacent form walls M engaged thereby will be exteriorly braced against their spreading outwardly and away from the opposite form walls. The desirability of this additional bracing so provided for the truss form structure is due to the geometry involvedthe height of the vertical form walls at the truss center rising to a maximum point where bracing from the spacer boards H at the base is relatively ineffective. By placing intermediate spacer boards I at a higher elevation to rest upon the stands K, as just noted, this deficiency is overcome with the result that the form boards M are also braced at higher points to furnish adequate backing therefor. In case of truss form structures of very considerable length, the height to which the form walls rise at the center may require that a still further tier of intermediate spacer boards be carried upon other like stands to be rested upon the intermediate spacer boards I just described, this top level of intermediate spacer boards being then disposed in the peak area of the vertical form boards to furnish the bracing there needed.

The top edge portions of the vertical form boards also require bracing to maintain a spacing therebetween the same as assured elsewhere by the ground G and base spacer boards H. For this purpose, I provide some relatively long wire clips 25 of heavy wire or the like (FIGS. 4 and 7), each bent to provide a pair of channels for reception of top portions of the vertical form boards engaged by the clip. The spacing of the two channels of this clip is such as to agree with the spacing for the vertical form boards along their bottom portions by the ground G and the spacer boards H and I. The number of such spacer clips applied to the top edge portions of the vertical form boards should be determined by the need therefor which depends largely upon the combined length of these vertical form walls. A spacing of two feet or so for these clips would be normal.

Between the channels of the wire clips 25, when applied in operative position, are elongated depressed middle portions 26 upon which are rested decking boards D forming part of the form structure. The width of each such board corresponds to the relatively wide space between the confronting faces of the vertical form boards M and O in the two sets thereof when operatively positioned upon adjacent beams B. When fitted in place to rest upon the depressed middle portions of two or more of the long clips 25, the top faces of the decking boards D will lie substantially flush with the inclined tops of the vertical form boards M and O, and slightly above the tops of the gables. They also provide top closures for the wide spaces between each pair of vertical form boards erected upon adjacent truss beams B. Concrete, when poured, is free to enter only into the narrower spaces spanned by the short wire clips 15, but not the wider spaces spanned by the longer wire clips 25 whereon the decking boards D are supported. In consequence, when the narrower spaces are filled to form the several parallel trusses, continued pouring will accumulate concrete on top of the form structure to be concurrently spread around by workmen so as to provide a slab S extending continuously over the entire area defined by the supporting walls X and Y of the building to form thereover an all-concrete roof which is united integrally with the supporting concrete trusses therebelow. When this stage of the operation has been completed, all further work is suspended to permit the concrete to seta period of perhaps a couple of days.

The eaves E which extend outwardly from the side walls X are also produced in the same concrete pouring operation. Suitable forms therefor are shown in FIG. 2. Each such form comprises a horizontal base form board 28 carried upon a frame 29 one side of which is afiixed to the outer face of one of the building side walls X. A main support for this base form board is furnished by heads 10 of the adjustable jacks J spaced apart, as needed, the foot 11 of each jack being rested upon the ground outside the building. The heads of these jacks are in engagement with the base board frame 29 so as to maintain it fixedly in a position substantially level with the top face of the ground G. Carried by this frame to upstand therefrom is a peripheral form board 34) which extends along the outer side and ends of the base form board 28 to provide a low border wall which holds within the confines thereof the concrete which is deposited upon the base board form. As a finishing touch, precast concrete moldings 31 are shown as affixed to the eaves along their free edges (FIG. 1).

In the process of erecting the buiding side walls X, means is provided for draining water from the eaves later to be formed. This consists of one or more vertical pipes 35 entombed within the side walls, each pipe at its lower end being outturned at 36 for discharge of water therefrom at a desired level over or under the ground. The drain pipes so provided are extended upwardly initially to a height slightly above the level of the eaves so as to protrude upwardly therefrom when the eaves are later formed. At that time, the protruding pipe end portions may be cut off flush with the eaves to receive and carry away water collecting thereon as it runs off the sloping roof surfaces, or otherwise.

During the stage of form erection, there is also installed provision for reinforcing the concrete roof structure and checking its expansion and contraction in response to changing thermal forces. For this purpose, a single long reinforcing rod 40 is extended horizontally over the ground G of each truss beyond its opposite ends for substantially the full width of the eaves. This rod may be suitably supported between the vertical form boards M and O, as by chairs which upstand from the ground. Other rods 41 having opposite end portions oppositely bent through approximately degrees are also extended vertically to lie within the king post 17 between the two access openings 0. One bent end portion of each rod 41 is then positioned so as to extend over the core 18 of one such opening, its opposite end portion being similarly extended to lie thereunder. Both rods 41 at the point of their lower bends are wired to each other at 42 and to the main reinforcing rod 40 whereby to be firmly secured in place. A plurality of wires 43 arranged coplanarly and in parallelism are also shown as strung across the top of the form structure where they may be carried by chairs to be embedded within the roof slab, when poured. These wires also extend into an eave portion 45 of the slab, the latter being extended outwardly to overhang beyond the gables of the end walls Y. Contraction and expansion 7 of the roof slab, in response to thermal changes, is checked adequately by the presence of these wires when embedded therein. The eave portions 45 are desirably finished by the addition of border moldings 31 thereto, as shown.

After installation of the several rails R, erection of the form structures is then started. The beams B adjacent opposite end walls Y of the building are first placed on the rails in approximately their correct positions. Adding of the grounds and vertical form boards then follows. When the base spacers and decking boards H and D are to be set in place, the supporting beams therefor are slid toward or from the proximate gables, as needed, for final spacing of the trusses to be erected thereon. This capacity for shifting of each beam, together with most of the form structure erected thereon along the supporting rails, assures a correct positioning of all the form structures whereby their spacer componentsthe base, intermediate and decking boards H, I and Dwill firmly engage along their longitudinal edges with the lower, middle and upper portions, respectively, of the vertical form walls provided by the boards M and O. Spreading of these walls in response to pressure from fluid concrete internally thereof is thereby effectively prevented. With continued erection of the form structures proceeding from one gable wall Y toward the other, or from opposite gable walls toward each other, an intermediate point is finally reached for location of the last truss beam. The space remaining for its accommodation will, in all probability, be different from that elsewhere provided for the other truss beams and form structures carried thereby. To meet this condition, the spacing components, viz., the boards H, I and D, should be of the requisite width for their correct fitting into the spaces between the vertical form walls rising from this last truss beam and those adjacent thereto on one or both sides thereof, as needed. This may involve trimming down of boards of the usual width, or use of wider boards where extra width is needed. Except for this one intermediate point, the spacing of the several truss form structures Will be uniform from end to end of the building.

Dismantling of the form structure is the final step. This operation proceeds expeditiously when performed by experienced workmen. The first step is to remove the base spacer boards H by tilting one side of one of them upwardly to free the other side for dislodgement from the ledge on its supporting beam B. With removal of the several base spacer boards, also the knock-down stands thereon and the intermediate spacer boards I which are then freed for withdrawal, the vertical form walls may be dislodged by pulling their bottom edges outwardly for disengagement from the beam ledges. The form boards Mand may then be withdrawn, and in so doing disengage their upper end portions from the channels of the wire clips which remain embedded within the concrete. The decking boards D too are then ready for removal; if necessary, the supporting wire clips therefor may be cut to facilitate their withdrawal. Finally, the supporting beams B are removed, leaving only the grounds G to be pulled off the bottom faces of the newly-formed trusses. If it be planned to have these grounds remain permanently attached to the trusses, then at the time of form erection nails 33 should be driven through these grounds with their upper end portions toed to protrude slantingly beyond their top faces, thereby to provide spiky means for anchoring the grounds to the concrete, when poured.

It will be noted that all components of the truss forms, when erected, will interfit and remain immovably in place free of fastening means therefor. This contributes to ease and speed of erection and subsequent dismantling, and also longer serviceable life. In addition, all spacer and decking boards are interchangeable and free of projecting elements so as to facilitate their handling and stacking.

These boards, also those used for the form walls, may

be used over and over again, many of them for trusses varying widely in length whereby to reduce to a minimum the number of special sizes and shapes required for operations in general. This is a feature of advantage applying to the rails, beams and grounds as well.

The roof structure of this invention embodies the novel feature of a concrete slab integrally joined to a plurality of supporting trusses also of concrete, the slab constituting a compression member which serves as a top chord for the structure in its entirety. The inclined top portions of the trusses are also compression members, and the fact that the slab supported integrally thereon is likewise under compression is a factor of importance. This is because of the resistance contributed by the trusses to the development in the slab of fractures 0r cracks in response to changing thermal conditions. A prolonged serviceable life, free of maintenance and repair work, is thereby promoted. It will be noted further that at their end portions, where the slab and trusses meet to rest their combined weight upon the building walls, thereby becoming subject to vertical compression forces, the concrete is materially thickened to provide an increased margin of safety. The desirability of this is emphasized by the eaves which extend outwardly beyond the building walls for a distance of perhaps two feet, all without any support therefor other than that inherent in the strength of the concrete itself plus the reinforcements added thereto. Repeated experience in the building of allconcrete roof structures, as herein disclosed, has demonstrated the various points of merit therefor, as herein specified, to be abundantly present whereby to assure thereto long life and little or no maintenance expense.

I claim:

1. A form structure for trusses to be erected between spaced walls of a building, comprising a beam extended for nearly the full distance between such spaced walls and supported from below at spaced points lengthwise thereof at an elevation approximating the wall tops, double sets of form components vertically erected upon the beam to provide a pair of spaced form walls extending lengthwise thereof to span the distance between the building walls, the bottom edges of the form Walls being rested upon the beam inwardly of its longitudinal edges, spacer means carried by the beam between the foam walls to engage therewith interiorly thereof adjacent their base portions to there maintain them apart a fixed distance from each other, other spacer means removably rested on the beam also engaged with the form walls exteriorly thereof along their bottom edge portions to maintain them in engagement with the base spacer means therebetween, and still other spacer means removably carried by the form walls at separated points adjacent their tops and extending therebetween to engage therewith for holding the form walls apart from each other a fixed distance the same as the spacing between the form walls along their bottom edge portions, a substantially continuous open top being thereby provided between the form walls for reception of concrete, when poured in a plastic state, which is free to spread between the form walls to till the space therebetween from end to end thereby to provide a truss with opposite end portions permanently supported upon the spaced building walls and therebetween temporarily by the beam.

2. A truss form structure as specified in claim 1 wherein the spacer means removably carried by the form walls at separated points adjacent their tops consist in each case of a wire clip bent to provide a pair of spaced channels adapted to receive and frictionally engage the top edge portion of one pair of the form walls.

3. A truss form structure as specified in claim 1 wherein the beam is relatively wide and the spacer means between the bottom edge portions of the form walls is a relative narrow ground loosely rested on the beam to lie inwardly of its opposite sides whereby to provide ledge portions therealong, the ground being extended along the beam for the full distance spanning the spaced building walls, and the spacer means engaging with the form walls exteriorly thereof along their bottom edge portions being rested upon a ledge portion of the beam.

4. A truss form structure as specified in claim 3 wherein spikey means upstands from the ground top face for anchorage in the concrete truss to be poured thereover whereby to secure the ground fixedly thereto.

5. A truss form structure as specified in claim 1 wherein a frame fitted in place between the form walls to extend through the space therebetween is adapted to serve as a core for providing a transverse opening through the concrete truss when molded therearound, and means carried by one form wall removably supporting the core in a fixed position adapted to freely release the core therefrom when the truss form structure is dismantled.

6. A truss form structure as specified in claim 3 combined with other like structures arranged in parallelism in spaced relation to provide means for molding a plurality of concrete trusses, and wherein the spacer means engageing with the form walls exteriorly thereof along their bottom edge portions is an elongated horizontal board having its longitudinal edge portions rested upon the ledge portions of adjacent beams supporting like truss form structures and in engagement with bottom edge portions of one of each of the form walls carried thereby.

7. A truss form structure as specified in claim 6 wherein the spacer means removably carried by the form walls adjacent their tops extends also between one form wall of each of two adjacent pairs thereof to close the space therebetween whereby concrete, when poured into the spaces between each pair of form walls, will be prevented from entering into the adjacent spaces exteriorly thereof.

8. A truss form structure as specified in claim 6 wherein a plurality of spaced-apart wire clips bent to provide spaced channels are fitted over the top edge portions of one form wall comprised in each of two adjacent pairs thereof to engage therewith and fixedly maintain the same in vertical positions, the wire clips between the engaged form walls being offset into a portion of lower elevation, and wherein spacer means in the form of an elongated board is removably fitted between one form wall of each of two adjacent pairs thereof and fixedly rested upon the offset portions of the wire clips to engage along its opposite longitudinal edges with the form walls adjacent thereto at a point close to the top edges thereof to brace the form walls against outward spreading when concrete is poured into the spaces therebetween while preventing entrance of concrete into the spaces between adjacent pairs of form walls.

9. A truss form structure as specified in claim 6 wherein the supporting means for the beams comprises a system of horizontal rails whereon each of the beams is rested with capacity for sliding movements thereupon toward and from each other to positions where the beam ledge portions are spaced apart the requisite distance for accommodating therebetween the horizontal spacer boards with their opposite longitudinal edge portions resting upon the ledge portions of the beams and in engagement with the vertical form walls of each of the two pairs thereof adjacent thereto.

10. A truss form structure as specified in claim 6 wherein a stand is rested upon the elongated horizontal board to upstand between two pairs of adjacent form walls, and a horizontal spaced board is rested upon the stand to extend the full distance between the two pairs of adjacent form walls for engagement with one wall of each externally thereof along a horizontal line at an elevation relatively close to the tops of such walls.

11. A truss form structure as specified in claim 10 wherein the stand comprises two duplicate boards formed with open ended slots permitting one board to be interfitted with the other to remain joined at right angles thereto in an upright position, but separable therefrom in response to sliding movement of one relative to the other in a direction parallel to the slots therein.

12. A truss form structure as specified in claim 5 wherein two like cores provide for two transverse openings through the truss, one on each side of a king post therebetween extending vertically to join with base and top portions of the truss, when completed, reinforcing means is extended horizontally between the form walls above the base spacer means therebetween for substantially the full length thereof, and other reinforcing means is extended vertically to lie within the king post and connect at its lower end with the horizontally extending reinforcing means at a mid point lengthwise thereof.

References Cited UNITED STATES PATENTS 1,221,567 3/1917 Moncure 24926 X 1,332,617 3/1920 Dodge 24927 1,538,496 5/1925 Wells 24927 1,864,043 6/1932 Gruber 24932 2,318,058 5/1943 Colburn 25131 3,064,392 11/1962 Avril 24927 X FOREIGN PATENTS 141,329 5/1951 Australia.

I. SPENCER OVERI-IOLSER, Primary Examiner.

J. S. BROWN, Assistant Examiner.