US 3566567 A
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Description (OCR text may contain errors)
March 2, 1971 YOSHIRO WATANABE 3,566,567
CONCRETE LOAD SUPPORTING STRUCTURE 3 Sheets-Sheet 1 Filed July 25, 1969 FIG.
YOSHIRO WATANABE flak 711% ATTORNEYS March 2, 1971 YOSHIRO WATANABE CONCRETE LOAD SUPPORTING STRUCTURE Filed July 25, 1969 '3 Sheets-Sheet a E[ fiik 29 26 2o 20 INVEN'IOR.
YOSHIRO WATANABE BY.
W/ffiflfi ATTORNEYS March 1971 YOSHIRO WATANABE 3,
CONCRETE LOAD SUPPORTING STRUCTURE Filed July 25, 1969 3 Sheets-Sheet 3 INVEN'I'OR.
YOSHIRO WATANABE ATTOR EYS United States Patent US. Cl. 52-250 3 Claims ABSTRACT OF THE DISCLOSURE A concrete load supporting structure of the type which comprises a plurality of relatively slender beams supported on girders, these beams being spaced and held in place by spacer strips whereby the beams are protected from becoming buckled under the influence of a concrete load.
This invention relates to improvements in and relating to a concrete load supporting structure and has particular reference to a structure of the type including open web steel joists.
Conventional concrete load supporting structures relied upon the use of beam materials of suflicient mechanical rigidity to withstand downward pressures of a concrete slab plus weight of concrete applying equipment, and hence such beams were necessarily heavy and costly. Steel beams, if lacking in such mechanical strength, would tend to buckle under the influence of concrete load.
Whereas, it is the primary object of this invention to provide novel, useful concrete supporting bed structures of this character which will eliminate the above noted disadvantages of the conventional structures and which will permit of the use of relatively slender steel beams such as round bars and the like for supporting a concrete load thereon without causing them to buckle or otherwise become deformed.
According to the invention, there is provided a concrete load supporting structure which includes a framework generally consisting of longitudinal and transverse wide-flange girders each having a top and a bottom flange and a web, said girders being criss-crossed at and carried on supporting columns, a plurality of latticed beam members extending in parallel with the transverse girders and arranged in a substantially parallel spaced-apart relation, each of which members consisting of an upper chord, a lower chord and a latticed chord connected therebetween, and having its ends supported on and secured to the longitudinal girders, a plurality of spacer strips arranged in a substantially parallel spaced-apart relation and in parallel with the longitudinal girders, each of which strips spanning over and interlinking two adjacent beam members at points where said latticed chords are hinged to said upper chords of the beam members, whereby a supporting bed in a criss-cross pattern is formed, and corrugated sheets laid over the bed and extending substantially at right angles to and in contact with said spacer strips.
These and other features of the present invention will be better understood from the following description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a plan View partially broken away of the concrete load supporting structure embodying the present invention;
FIG. 2 is a transverse cross-sectional view on an enlarged scale taken on line IIII in FIG. 1 with a concrete slab formed in the base;
FIG. 3 is a longitudinal cross-sectional view on an enlarged scale taken on line III-III in FIG. 1;
FIG. 4 is a frontal view on an enlarged scale of a 3,566,567 Patented Mar. 2, 1971 spacer strip for use in the first embodiment shown in FIGS. 1 through 3;
FIGS. 5 through 7, inclusive, show a second embodiment;
FIG. 5 showing a view corresponding to FIG. 2; FIG. 6 showing a view corresponding to FIG. 3 and FIG. 7 showing a modified spacer strip.
Like numerals refer to like parts throughout the drawings. Reference is first had to FIG. 1 which shows a concrete load supporting structure generally designated at 10 and considered here as a building floor for purposes of illustration. This structure generally includes a steel framework consisting of a pair of opposed longitudinal girders 11 extending in criss-crossed relation with a pair of opposed transverse girders 12. These pairs of girders are supported on supporting columns 13 at as many points of criss-cross as may be required for a particular application.
Each girder 11 is an H-shape steel in common use having a top flange 14, a bottom flange 15 and a web 16 as shown in FIGS. 2, 3, 5 and 6.
Designated generally at 17 are a plurality of open Web steel joists or latticed beam members of a relatively slender steel such as round bars each consisting of an upper chord 18, a lower chord 19 and a latticed chord 20. The latticed chord 20 is hinged for instance by welding as at 21 and 22 to the upper and lower chords 18 and 19, respectively. The respective ends of the upper and lower chords are brought together and secured via suitable plate members 23 to the longitudinal girders 11 by means of welding, so that the latticed beams 17 run in a substantially parallel, spaced-apart relation and substantially in parallel with the transverse girders 12.
Designated at 24 is a spacer strip which in one preferred form assumes the shape shown in FIG. 4 and which has a straight, horizontal portion 25 and inwardly bent, hooked end portions 26. The straight, horizontal portion 25 has a length substantially equal to the spacing or span between adjacent latticed beams 17. Each of these spacer strips 24 spans over and interlinks two adjacent latticed beam members 17, for which purpose the hooked end portions 26 are arranged to hook around the upper hinges 21 of the beam members. As illustrated in FIG. 1, a plurality of spacer strips 24 are arranged in a substantially parallel, spaced-apart relation, and they intersect the latticed beam members 17 thereby forming a concrete load supporting structure in a criss-cross pattern. It will be noted that the terminating groups of spacer strips 24 have one end portions devoid of the hooked portions 26 and bent slightly upward as at 24 in FIG. 3 so that with these end portions secured to the top flanges of the girders 12, the spacer strips 24 lie substantially flush with the top flange surface.
Designated at 27 is a corrugated steel sheet or the like which is laid over the supporting structure 10 and extends substantially at right angles to and in contact with the spacer strips 24. Over this corrugated steel sheet is cast a concrete slab containing therein reinforcing [bars (not illustrated) The concrete load supporting structure thus constructed according to the invention features the provision of spacer strips 24 which serves two-fold purposes. Firstly, the spacer strip arrangement restricts lateral movement of the latticed beams 17 which are made of less costly round bars and prevents the latter from buckling or otherwise becoming deformed when a concrete slab 28 is cast over the supporting structure. Secondly, since the spacer strips 24 are disposed in contact with the corrugated sheet 27 over which a concrete is cast, they transfer the load of concrete for concentration at the stronger part of the latticed beam structure, which lies at the upper hinges 21 of the beams, thereby avoiding direct load distribution through the relatively weak mid-portions of the upper chords 18 which lie between the hinges 21. It is in this connection important to locate and hook the spacer strips 24 at the upper hinges 21 of the latticed beams 17, for which purpose they may be provided if necessary with stopper means 29 as shown in FIG. 4 to prevent lateral movement of the upper chords 18.
Reference to FIGS. 5, 6 and 7, inclusive, shows the second embodiment of this invention which is analogous in basic concept to the first embodiment hereinabove described. The second embodiment offers the advantage that thickness of a concrete slab for a given design requirement may be substantially reduced and at the same time, height of the resulting floor slab as a whole above the base course may be considerably lowered. This advantage accrues from the following concrete supporting structure.
The upper chord 18 of each latticed beam member 17 is provided with an upgrade slope 30 extending along the latticed chord 20, so that with the ends of the beam 17 secured on the longitudinal girders 11, the main horizontal portion of the beam 17 lies below the level of the top flange 14 of the girder 11. These beam members 17 are held in position in a manner similar to the first embodiment by means of a plurality of spacer strips 24 each having a straight, horizontal portion 25, upright arms 31 and hook-like ends 32 as shown in FIG. 7. With each spacer strip 24 spanned over two adjacent beam members 17 and its ends 32 hooked around the hinges 21 of the beam members 17, the horizontal portion 25 of the strip 24 on which the corrugated sheet 27 is laid becomes situated below the level of the top flanges of the girders. The terminating groups of spacer strips 24 have their respective flat ends supported on and secured to ledges 3 3 projecting from the webs 16 of the transverse girders 12 as seen in FIG. 6. Similar ledges 33' are formed on 'the webs of the longitudinal girders 11 for supporting thereon the ends of the corrugated sheets 27 arranged substantially at right angles to the spacer strips 24 as seen in FIG. 5. As a concrete slab is cast over the corrugated sheets, the arms 31 and hook portions 32 of the spacer strips are embedded in the concrete layer so that these portions of the strips lend themselves to the effect of a combined beam with the latticed beam members 17 and thus augment the load supporting capabilities of the resulting concrete floor.
As is obvious to those skilled in the art, substantial portions of the latticed Ebeam members 17 as used in the first embodiment illustrated specifically in FIG. 2 may be removed after the concrete slab is cured and hardened.
It will be understood that the present invention is not limited to the precise form and arrangements of the concrete load supporting structure, but many modifications and changes may be made therein without departing from the scope of the appended claims.
What is claimed is:
1. In a concrete load supporting structure which includes a framework generally consisting of longitudinal and transverse wide-flange girders each having a top and a bottom flange and a web, said girders being crisscrossed at and carried on supporting columns, a plurality of latticed beam members extending in parallel with the transverse girders and arranged in a substantially parallel spaced-apart relation, each of which members 'consisting of an upper chord, a lower chord and a latticed chord connected therebetween, and having its ends supported on and secured to the longitudinal girders, a plurality of spacer strips arranged in a substantially parallel spaced-apart relation and in parallel with the longitudinal girders, each of which strips spanning over and interlinking two adjacent beam members at points where said latticed chords are hinged to said upper chords of the beam members, whereby a supporting bed in a criss-cross pattern is formed, and corrugated sheets laid over the bed and extending substantially at right angles to and in contact with said spacer strips.
2. The structure according to claim a1 wherein said spacer strips are arranged substantially flush with the top flanges of the girders.
3. The structure according to claim 1 wherein said spacer strips are arranged below the level of the top flanges of the girders and partly embedded in the concrete slab.
References Cited UNITED STATES PATENTS 471,772 3/1892 Orr 52-326X 644,914 3 1900 Himmelwright 52--326 1,804,132 5/1931 Tashjian 52335X 1,982,343 11/1934 Kane 52--252 2,055,701 9/1936 Palmer 52335X 2,191,828 2/1940 Bruehlman 52326 FOREIGN PATENTS 990,646 6/1951 France 52-326 ALFRED C. PERHAM, Primary Examiner US. Cl. X.R.