US2128137A - Building structure - Google Patents

Description

Aug. 23, 1938. R. G. GODSON I 2,128,137

BUILDING STRUCTURE Filed Dec. 8, 1934 3 Sheets-Sheet 2 KZZ Ga s 01s;

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fi I I BY Q/TZwL/MJM ATTORNE YS.

R. G. GODSON BUILDING STRUCTURE Filed Dec. 8, 1934' 3 Sheets-Sheet 5 Fla/6.

IN VENTOR,

ATTORNEYS.

Patented Au 23, 1938 UNITED STATES BUILDING STRUCTURE: ReginaldG. Godson, Toronto, Ontario, Canada Application December 8, 1934, Serial No. 758,690

In Canada February 21, 1934 16 Claims.

The present invention relates to new and useful improvements in the design and erection of buildings and other structures, same comprising a geometric load-distribution system for placing loads economically on supporting beams which carry the floors in the aforesaid structures.

In modern structures the cost of the floor-system, beams and columns is an important percentage of the total cost. The cost varies directly with the weight of the structure, which in turn depends on the floor loads and the span of the floor beams; and the span becomes a more important factor as the spacing of the columns increases. Lastly incidental design features etc., such as ties, struts and bracing, add to the cost by providing material that apart from the specified requirements for rigidity, perform no useful work supporting the floor loads of the structures.

The usual types of floor construction, in use today, carry the floor loads directlyonto the supporting beams or marginal girders, Without attempting to place these loads on the supporting beams tobest advantage.

In an ideal design, the floor loads should be transmitted directly to the columns. Failing this, the next best arrangement would be to carry-as much of the floor loads as possible to the ends of the marginal beams or girders, thus reducing the bending moment and subsequent deflection in the beams; resulting in a comparatively light and rigid structure. Moreover, the floor loads should be transmitted to all the floor beams, thus mak-- commonly employed; The present system makes it possible to reduce the cost of building construction by using lighter and shallower beams and lighter slabs, and by decreasing the story heights .50 of buildings. and other structures. It is applicable to any type of construction, same' being. a geometric arrangement of the floor units by means of which the floor loads are carried in ever increasing amounts towardsthe ends of the main 651, or marginal floor beams, instead of distributing them uniformly, overthe entire length of the said beams. This, isaccomplished by placing. a series of secondary beams arranged in circumscribed relation? within the panel, and'a plurality of cone centric groups of beams of smaller extent within the secondary beams, as. will ,be explained herein.

' A comparison of the costs of floor slabs and main supporting beams, designed according to the, present system, with other floor systems. in common. use shows that very'ia'ppreciable savings can be made in the' cost of construction. The actual amount of these savings due to reduced. depths ofslabs. and beams, in masonry walls, partiti'ons plastering, piping, wiring, etc., is also a substantial item in cost of construction. The reduced dead loads. and building heights also effect savings in columns and footings, particularly in structures designed to resist wind forces. I In bridge construction the concentrated wheel loads usually govern the design of the floor beams and stringers, although the slab itself may be reduced by the application of the present geometric load-distribution systemand such reduction in the slab dead loads'results in economy in design of the main trusses and girders of the main structure. Tests of the present systemhave been made and same have proven that the theory involved is substantiatedin practice.

In the accompanying drawings forming part of the present specification, I have illustrated the structural features embodied in my invention, in which:

Figure l is a plan view showing the layout'of a ring floor system, for a typical panel of a building or similar structure, in which is shown a number of boundary or marginal girders, a series of secondary beams arranged in circumscribed relation in the panel, and a plurality of concentric groups of beams of smaller extent, each group having its central'point coincidental with 40 that of one of the secondary beams.

Figures 2 and 3 showplan views'of twomodifications of a triangular floor system fo'r'buildings etc., arranged similarly to the ring floor system of Figure 1. Figure 4 shows a plan layoutof a rectangular floor systemfor buildings etc., having a similar arrangement to those just described. Figure 5 is a-plan view ofv a modification of Figure 4, the. rectangles being formed by'means of joists arranged as illustrated, in the section shown in Figure 6.

Figure 6 is acentral vertical transverse sec-, tion online 6-6 of Figure 5.

Figure 7 shows a plan of a modified form of right-angular floor system, the loads being carried on each joist in turn near the ends thereof, the final or accumulated reactions being placed on the main beams or marginal girders between the columns near their points of support.

Figure 8 shows a plan of a splayed floor systern, in which the end reactions of the floor supporting structural units are split up into two or more reactions; the latter being transmitted to the marginal girders or beams which extend between the columns at points near their points of support.

Figure 9 shows a typical part plan layout of a geometric load-distribution system for a building.

Figure 10 is a plan view of a rectangular panel floor system using the geometric ring load-distribution system.

Figure 11 is a plan layout of a floor panel in which the rings or strips of floor are irregularly spaced with reference to each other.

Figure 12 is a transverse vertical section on line l2l2 of Figure 11 for semi-detached and isolated rings, illustrating graphically the relative strength of the rings shown in said figure.

Figure 13 is a transverse vertical section on line graphic illustration of the relative strength of the rings.

Figure 14 is a plan of a floor panel, showing the arrangement of reinforcing material, located near the top of the slab used for the panel.

Figure 15 is a plan of a floor panel showing the arrangement of reinforcing material located near the bottom of the slab used for the panel.

Figure 16 is a vertical transverse half-section on line l6l6 of Figure 15.

Figure 17 is a vertical transverse half-section on line I1|l of Figure 15.

Figure 18 is a graphical diagram illustrating a triangular loading on a supporting beam.

Figures 1 to 8 illustrate several geometric systems, the fundamental basic principles of which are substantially the same in theory, namely, a geometric arrangement of the floor units which distributes the floor loads on to the supporting floor beams or marginal girders, in proportion to their size. It follows that the larger units being located farthest from the approximate center of the supporting beam, the greatest floor loads will be placed on the supporting beam near its points of support, thus making it possible to have lighter and shallower beams in the structure, as is well understood in the design of beams, in common practice. 7

Assuming each geometric structural floor unit to be of unit width, it may be readily seen that:

(1) The load on each of the rings or circular strips of floor I to 6 inclusive as shown in Figure 1 is proportional to its radius.

(2) The load on each triangular strip of floor l, 8, 9 and In as shown in Figure 2 is proportional to its length,

(3) The load on each rectangular strip of floor ll, I2, I3 and M as shown in Figure 4 is proportional to its length.

Therefore the concentrations on the supporting floor beams, due to the reactions of these floor units increase from zero at the center to a maximum at the outer strips; in other words the beams or'marginal girders, l5, l6 and H are loaded with a continuously increasing load, increasing uniformly from zero or a minimum at the center to a maximum at the outer strips or secondary beams, 6, I0, M respectively. According I3--l3 of Figure 11, showing a similar to data obtainable from any structural handbook, the maximum bending moment in a beam, simply supported, and loaded with a triangular loading, increasing from zero at its center to a maximum at the ends, is only two-thirds of that for a similar beam loaded with a uniform load over its which, according to present methods of design, is

one of the most economical distributions in com mon use. This explanation is based onv universally accepted principles.

In the case of a right angular floor system as shown in Figure 7, the floor units, as illustrated by l8, I9, 20 and 2|, increase in size from the center ofthe panel until the boundary or marginal beams are reached. Each unit transmits its load near the ends of the unit directly supporting it, until the final accumulated reactions are placed on the supporting beams 22, 22 etc., near their points of support. It can be readily seen that the bending moments involved are greatly reduced by reason of the floor loads being concentrated near the ends of the supporting members.

The splayed beam system illustrated in Fig. 8, demonstrates in an elementary manner how the floor loads carried by astructural unit such as 23 can be split up into two or more reactions 24, 25 and placed on the supporting or marginal beams 26, 26 etc., near their points of support, thus reducing the bending moment in the supporting floor beam according to the distance these loads are placed away from the centers of said beams or girders.

Figure 3 is a modification of Figure 2.

Figure 5 is a modified arrangement of Figure 4 in which the rectangles are formed by means of continuous units as illustrated in section in Figure 6. The dotted portions of the floor units illustrated by 21, 28 and 29 do not form part of the geometric system and do not carry the floor 30 or the ceiling 3|.

Consider a case in which the whole floor is constructed of a plurality of concentric rings or strips of suitable material, or of any other geometric shape that can be mathematically analyzed and practically used: let Figure l represent a plan of a floor panel made up of a series of vsuch rings as outlined above, the floor being assumed to be symmetrical about the boundary beams or marginal girders and only half the rings being shown for the sake of convenience. As already explained, any other practical geometric shape would do. However, the ring is selected for this discussion, as it appears to possess certain advantages over other shapes. Assume each ring to carry a strip of floor one foot wide, and the centers of each circular strip to be in exact feet from the center of the beam; that is the annular center of the first ring or strip to be one foot from the center of the main or marginal beams; the annular center of the second ring to be two feet from the center of the main beams and so on.

It may be easily proven that the reaction of each ring on the supporting beam is proportional to the radius of the ring or strip. In other words, in the geometric load distribution system,

' located around the panel.

the supporting beam is loaded with a triangular continuous loading, increasing uniformly from zero at the center to a maximum at the outer rings.

In actual tests made to demonstrate the present system of construction, reinforced concrete construction was selected as being the best adapted to fully demonstrate the principles of the geometric load-distribution system, because it was considered that if a solid slab would distribute the panel floor loads to the supporting beams, Without suflicient transfer of the load in the shortest direction to cause rupture in the concrete, the behaviour of semi-detached or isolated rings would naturally follow. Steel boundary supporting beams usually placed between the columns, simply supported, were decided upon as best fitted to illustrate the distribution of loads, due to the present system. The tests disclosed that for working loads the distribution of loads to the supporting beams is in substantial conformity with the geometric load-distribution theory described herein.

It can be seen from Figure 9 that the rings of the same radius are made standard throughout the building for any particular floor loading; their detail is exactly similar whether it takes the form of slab reinforcement semi-detached or isolated rings. However it is important to note that in the case of semi-detached or isolated rings the spacing of the rings depends on economical requirements of design; the smaller the rings the greater the space between them according to the requirements of building specifications and codes.

Figure 10 shows a rectangular typical floor panel in which the ratio of the length and the breadth of the panel is in the substantial proportion of two to one. It can be seen that under this system the small beams are fully loaded and the longer beams are only partially loaded as the result of these arrangements, and all the outer rings can be made in tangential contact.

Figure 11 illustrates a typical layout for a semi-detached and isolated ring floor system, consisting of a series of irregularly spaced rings 32, 38, 39, 40 and 4|, as opposed to a solid floor slab. It may be seen that if the outer rings 32, 32 etc., are designed to carry all the load on the central floor area 33, this load will be carried back near the ends of the main supporting beams at points 34, 35 etc., through the reactions of these outer rings, thus reducing the bending moment in the main beams or girders 36, 36 etc., This reduction in bending moments is seen to be greater than in the case of the slab where each ring is assumed to carry a portion of the central floor area 33.

In the case of a solid floor slab, the central floor area 33 Figure l is treated as a suspended span for the purpose of design supported on the four surrounding discs, each disc composed of a series of rings I to 6 inclusive as shown in Figure 1, by means of a rectangular grid 42 or equivalent means as shown in Figure 15.

In the case of the isolated ring design the central floor area 33 is supported by the four outer rings 32, 32 etc., Figure 11, on a circular ring 31, or other equivalent means of support.

Figures 12 and 13 represent graphically the size and stiffness of the rings required for the panel as shown in Figure 11 in which figures the rings 32, 33, 39, M! and El are shown in section.

It will be noted that the tangential rings 32, 32 etc., support each other laterally at points of contact with each other preventing any torque in the rings themselves.

It is important in the discussion We have in hand that the type of construction be such that there is no tendency for the panelfloor loadings to travel to the main beams ormarginal girders in the direction normal thereto. Therefore no members are introduced in the present system whose strength and stiffness are such as to provide the means for carrying such loads in a direction normal to the main beams, or towards their center.

In reinforced concrete construction, therefore, designed according to the present system, no reinforcement is introduced to take care of any moment or shear along lines normal to the main beams, and the torque in the rings is assumed to be distributed throughout the disc comprised of the series of rings I to B inclusive in Figure 1.

Practical tests demonstrated the ring action in the slab and no evidence was found to indicate any torsional shear failure in any part of the slab thus certifying to the correctness of the above assumptions.

In the case of any other type of construction consisting of semi-detached or isolated rings care must be taken not to employ any method or arrangement to prevent tilting of the rings and the accompanying torque, which might constitute a system having considerable strength and stiffness, in a direction normal to the main beams and thus prevent ring action and the desired distribution of loads on to the main supporting beams.

As illustrated in-Figure 9 by rings 44, 45 etc., where the arc of the ring subtends central angles less than 180 degrees, the moments and torques in such segments of rings decrease considerably as the central angle diminishes, thus making additional savings in material possible in the floor over those outlined above.

Practical tests show the ratio of the measured deflection to the calculated deflections on the basis of triangular loading and uniform loading is 41; '73; 100. In other words the actual deflection is only 0.562 of the calculated deflection for a triangular loading; as proportionally represented in Figure 18 and still further reduction factors may be found to'be practical.

In the case of a, solidslab floor, the rings are assumed to be partially restrained at the supports and laterally supported for their entire perimeter by the shear in the slab and no allowance made for torque. These assumptions are fully justified by practical performance as proved in actual tests. The maximum negative moment occurs at the supporting beams on the line 46, 46 etc., Figure 14, and the maximum positive moment occurs at the center of the half rings on the line 41, 51 etc., Figure 15. The points of inflexion are assumed to be for practical purposes on a line 48, l8,'etc., Figures 14 and 15, making an angle of substantially about 45 degrees with the diametral line of the rings, which lies parallel with the boundary beams.

The floor is designed for the maximum posilow, and providing hollow fillers beneath them, as at 12, 13 Fig. 12 of any material to keep the ceiling level. The reinforcement 49, 50 etc., Figures 14 and 17, required to resist the negative moments is located near the top of the rings and extends between the points of inflexion 48, 48 etc., on both sides of the supporting beam as shown in Figure 14. The reinforcement 5|, 52 etc., required to resist the positive bending moments in Figure 15, is located near the bottom of the rings as is shown in said figure. This reinforcement 5|, 52 etc., is shown continuous at 53, 54 etc., in Figures 15 and 1'7 for the entire circle, for practical purposes, but need only extend between the points of infiexion 48, 48 etc., Within any particular panel. Extra compression reinforcement is provided where necessary at 55, 56, 5'! etc., Figure 17 located at the bottom of the slab and extendingbetween the points of inflexion 48, 48 etc., Figure 15, on both sides of the supporting beam as shown in said figure.

The reinforcement shown in Figure 15 by 58, 59 etc., located at the bottom of the floor and normal to the diagonals of the panel is introduced to strengthen these areas of the floor and to tie the discs together.

The reinforcement shown in Figure 14, at 65, 6| etc., located at the top of the floor around the columns, is introduced to strengthen the corner area of the panels, as initial failure tends to occur at the top of the slab near the ends of the beams, and roughly parallel thereto.

Figures 16 and 17 represent graphically the relative strength and stifiness of rings 62 to 61 inclusive for a solid floor.

In the case of semi-detached or isolated rings as shown in Figure 11, the rings are assumed to be partially restrained and designed to resist bending and torsional moments. Tests reveal that the torsion developed is only a small part of that indicated by free torsion equations. However, judgment must be used based on the strength and stiffness of the constructional methods employed.

As before mentioned, Figure 11 shows the layout for a panel constructed of semi-detached or isolated rings and Figures 12 and 13 give a graphical representation of the relative size and stiffness of the rings required.

In the case of a solid floor, the central area 42, Figure 15 is designed exactly the same as an ordinary two-way slab and reinforcement l4, 14 etc., is provided located near the bottom of the slab as shown in Figure 16 or any other suitable means of support may be employed.

In the case of semi-detached or isolated rings, this area 33 Figure 11, may be supported on a curved ring 3'! as shown in Figure 11, or by any other practical method.

In the description of the present system I have shown the outer rings to be tangential in. order to best describe the distribution of loads to the supporting beams, however in some instances it is advantageous to continue the systems farther by providing overlapping or interlocking rings 68, 69 etc., as shown in Figure 10.

These rings would be designed to carry a certain percentage of the floor load depending on the relative stiffness of the rings which overlap or interlock, etc.,

While I have described this structure for floors of buildings, bridges, and other structures, it is readily seen that the present system of construction and design may be readily applied for use in connection with roofs of any kind and particularly in connection with barrel and shell roof construction, similar to those used for skating rinks and other auditoriums. In the latter case the rings will naturally conform to the pitch or curvature of the roof being designed. In the extreme case where these rings are almost vertical they will act as a series of arches distributing the loads almost vertically on the supporting beams or Walls, increasing from a minimum at the center of the system of rings, to a maximum at the rings farthest from the center of the ring system.

From the above description it will be seen that I have provided a system of construction which accomplishes all the advantageous features set out in the preamble of this specification.

I claim:

1. An arrangement of floor panel construction, comprising a number of marginal girders connected to each other to form the outline of a panel, a. plurality of panel beams each supported on a marginal girder, and arranged to deliver panel load concentrations thereto, which increase from a minimum at a point intermediate the ends of the girder to a maximum nearer the ends. of the same.

2. An arrangement of floor panel construction, comprising a number of marginal girders connected to each other toform the outline of a panel, a plurality of panel beams each supported on a marginal girder at a plurality of points, and arranged to deliver the maximum panel load concentrations near the ends of said girder.

3. An arrangement of floor panel construction, comprising a number of supporting columns, a number of marginal girders carried by said columns, a series of secondary beams arranged in circumscribed relation about the panel, each being partially in said panel and partially in an adjacent panel and carried on one of the marginal girders, and a plurality of concentric groups of beams of smaller extent, which extend in both of said above described panels, each group having its central point coincidental with that of one of the secondary beams, such arrangement of panel beams being adapted to deliver load concentrations on. each of the marginal girders, which increase from a minimum near the center of each group of panel beams, to a maximum at points where the loads from the secondary beams are delivered to the marginal girders.

4. An arrangement of floor panel construction, comprising a number of marginal girders connected to each other to form the outline of a panel, a series of secondary beams arranged in circumscribed relation in the panel, each mounted on one of the marginal girders, and a plurality of concentric groups of beams of smaller extent, each having its central point coincidental with that of one of the secondary beams, such arrangement of interior panel beams being adapted to deliver panel load concentrations on each of the marginal girders, which increase from a minimum near the center of each group of panel beams to a maximum at the points Where the loads from the secondary beams are delivered to the marginal girders.

5. An arrangement of floor panel construction comprising a main girder, a series of secondary beams, each having its central point on the approximate longitudinal center line of said girder, and a plurality of concentric groups of beams of smaller extent, each having its central point coincidental with that of one of the sec- Jond'ary beams, such arrangement of secondary beams and beams of smaller extent being adapted to deliver load concentrations on the main girder, which increase from a minimum near the center of each groupof beams toamaXimum at points where the loads from the secondary beams are delivered to the marginal girders.

6. An arrangement of floor panel construction, comprising a number of supporting collumns, a number of marginal girders carried by said columns, a' series of secondary beams arranged in circumscribed relation in the panel, each mounted on one of the marginal girders, and having its central point intermediate the ends: of said girder, and a plurality of concentric groups of beams of smaller extent, each having its central point coincidental with that of one of the secondary beams, such arrangement of interior panel beams being adapted to deliver panel load concentrations on each of the marginal girders, which increase from a minimum near the center of each group of panel beams to a maximum at the points where the loads from the secondary beams are delivered to the marginal girders.

7. An arrangement of floor panel construction for delivering floor panel concentrations to the boundary beams at points adjacent the ends. of said beams, comprising a number of connected boundary beams forming apanel therebetween, a series of rectangularly arranged floor panel beams ultimately supported by the boundary beams, each beam of which beginning at the approximate center of the panel delivers its load reactions near the ends of its adjacent and successive panel beams in turn, until the accumulated load reactions of all the interior panel beams are delivered on the boundary beams in the manner specified.

8. An arrangement of floor panel construction, comprising a number of supporting columns, a number of marginal girders carried by said columns, a series of arc-shaped secondary beams arranged in circumscribed relation in the panel, each mounted on one of the marginal girders, and with its central point near the approximate center of said girder, and a plurality of concentric groups of arc-shaped beams of smaller extent, each having its central point coincidental with that of one of the secondary beams, such arrangement of interior panel beams being adapted to deliver pan-e1 load concentrations on each of the marginal girders, which increase from a. minimum near the center of each group of panel beams, to a maximum near the ends of said girders.

9. An arrangement of floor panel construction, comprising a number of supporting columns, a number of marginal girders carried by said columns, a series of angular-shaped secondary beams arranged in circumscribed relation in the panel, each mounted on one of the marginal girders and with its central point near the approximate center of said girder, and a plurality of concentric groups of angular-shaped beams of smaller extent, each having its central point coincidental with that of one of the secondary beams, such arrangement of interior panel beams being adapted to deliver panel load concentrations on each of the marginal girders, which increase from a minimum near the center of each group of panel beams, to a maximum near the ends of said girders.

10. An arrangement of floor panel construction, comprising a number of supporting columns, a. number of ,marginal girders carried by said columns,- a series of U-shaped secondary beams arranged in circumscribed relation in the panel, each mounted on one of the marginal girders, and with its centrallpoint'near the approximate center of said girder, and a plurality of concentric groups of U-shaped beams of smaller extent, each having its central point coincidental with that of one of the secondary beams, such arrangement of interior panel beams being adapted to deliver panel load concentrations on each of the marginal girders, which increase from a minimum near. the center of each group of panel beams, to a' maximum' near the ends of said girders. 1

11. An arrangement of floor panel construction, comprising a number of supporting columns, a number of marginal girders carried by said columns, a series of secondary beams arranged in circumscribed relation in the panel, each mounted on one of the marginal girders, and with its central point near. the approximate cen ter of said girder, and a plurality of concentric groups of beams of smaller extent, each having its central point coincidental with that of one of the secondary beams, reinforcing members in each of the panel beams near the top surface thereof, for carrying the negative bending moments of such beams where they cross the marginal girders, and reinforcing members in each of the panel beams near the bottom thereof for carrying the positive bending moments in said beams, such arrangement of interior panel beams being adapted to deliver panel load concentrations on each of the marginal girders which increase from a minimum near the center of each group of. panel beams, to a maximum near the ends of said girders.

12. An. arrangement of floor panel construction, comprising a number of supporting columns, a number of marginal girders carried by said columns, a series of secondary beams arranged in circumscribed relation in the panel, each mounted on one of the marginal girders, and with its central point near the approximate center of said girder, and a plurality of concentric groups of beams of smaller extent, each having its central point coincidental with that of one secondary beam, reinforcing members in. each of the panel beams near the top surface thereof for carrying the negative bending moments of such beams where they cross the marginal girders, said members extending substantially between the adjacent points of contraflexure in adjacent building panels, and reinforcing members in each of the panel beams near the bottom thereof for carrying the positive bending moments in said beams, such members extending substantially between the points of co-ntrafiexure within adjacent building panels, such arrangement of interior panel beams being adapted to deliver panel load concentrations on each of the marginal girders, which increase from a minimum near the center of each group of panel beams, to a maximum near the ends of said girders.

13. An arrangement of floor panel construction, comprising a number of supporting columns, a. number of marginal girderscarried by said columns, a series of secondary beams arranged in circumscribed relation in the panel, each mounted on one of the marginal girders, and with its central point near the approximate center of said girder, and a plurality of concentric groups of beams of smaller extent,

each having its central point coincidental with that of one of the secondary beams, reinforcing members in each of the panel beams near the top surface thereof for carrying the negative bending moments of such beams where they cross the marginal girders, said members extending substantially between the adjacent points of contraflexure in adjacent building panels, and reinforcing members in each of the panel beams near the bottom thereof for carrying the positive bending moments in said beams, some of such members extending substantially between the points of contraflexure within adjacent panels and others of which extend throughout the full length of the panel beams, such arrangement of interior panel beams being adapted to deliver panel load concentrations on each of the marginal girders, which increase from a minimum near the center of each group of panel beams, to a maximum near the ends of said girders.

14. In a floor panel construction having a number of marginal girders forming the outline of the panel, an arrangement for delivering floor panel load concentrations to the marginal girders which increase from a minimum at a point intermediate the length of each girder to a maximum towards the ends of same, comprising means which are geometric shaped in plan view for transmitting to said girder loads due to panel loading in such a manner that the maximum bending moment created in each of the marginal girders is less than if the panel load were delivered to the said girders so as to create a uniform loading on each girder.

15. An arrangement of floor beam construction for delivering load concentrations to a girder which increase from a minimum at a point intermediate the length of the girder to a maximum towards the ends of same, comprising a plurality of beams which are geometric shaped in plan view, mounted substantially in an axial manner and solely on the said girder, so that the load concentrations occur on the girder in the order specified.

16. An arrangement of floor panel construction for delivering floor panel concentrations to the boundary beams at points adjacent the ends of said beams, comprising a number of connected boundary beams forming a panel therebetween, a series of rectangula-rly arranged floor panel beams, ultimately supported on the boundary beams, each interior panel beam beginning at the approximate center of the panel being arranged to receive a plurality of unequal load reaction concentrations from its adjacent panel beams, near the ends thereof, until the accumulated load reactions from all the interior panel beams are delivered to the boundary beams in the form of concentrations in the manner specified.

REGINALD G. GODSON.

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