US 2103859 A
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Description (OCR text may contain errors)
Dec. w. w. MACFARREN 2,103,359
BUILDING. CONSTRUCTION s Sheets-Sheet 1 Filed July 25, 1936 FIG.
Dec. 28, 1937. w.'w; MACFARREN 2,103,359
7 BUILDING CONSTRUCT IDN Filed July 25, 1936 s Sheets-Sheet 2 INVENT OR.
Dec. 28, 1937..
w. w. MACFARREN 3,859
BUILDING CONSTRUCTION Filed July 25, 1936 a Sheets-Sheet s INVENTOR.
I/ I 3 A. R
Patented Dec. 28, 1937 UNITED STATES PATENT TQFFICE Claims.
My invention relates tobullding construction and more particularly to roofs, and is particularly well adapted 'fordwelling houses, bungalows, and other small buildings. Certain features of the construction however, are also adapted for use in large mill and manufacturing buildings, as will appear later. V
Inthe drawings: I
Fig; 1 is a skeleton plan of a rectangular roof frame. according to my invention...
' Fig. 2 is an elevation of the same, including the outside supporting, orwall columns.
Fig. 3.is a floor plan of a circular bungalow.
Fig. 4 is a floor plan of an elliptical bungalow.
Fig. 5 a diagrammatic elevation of a mill building. 1 I Fig. 6 is a diagram of some catenary curves.
Fig. 7 is a diagrammatic cross section on the line I--I of'Fig. 1. p N
Fig. 8 is an enlarged cross section through the outsidewall of any figure. I
Fig. 9 is an elevation of a portion of a corner outside wall column.
Fig. 10 is a cross section of a latticed welded floor beam. r
Fig. 11 is a horizontal cross section of, a corner outside wall column. V f
Fig. 12 is a horizontal cross section of am outside wall column. v a v Fig. 13 is a horizontal cross section of an inside wall column.
Fig. 14 is an elevation of the circular bungalow of Fig. 3.
Fig. 15 is a diagrammatic side elevation of a a stand- 'mill building.
Fig. 16 is a diagrammatic end elevation of the same.
If the house is to have a cellar, thesame may be constructed in any suitable way. If not, the preferred construction isa concrete foundation wall and a concrete floor slab, both to be suitably reinforced and tied together. .On 'top of a the walls there is laid a steel bar or. channel I,
secured to the walls by suitable foundation bolts (not shown).
Referring to Fig. 8, the base channel I is laid back up, and may be levelled and grouted underneath. On top of the channel I there are spaced wall columns 3 which may be secured to the channel I by foot bolts 4, which mayhave their heads spot Welded'to' the underside of the channel.
When the concrete foundation has set, the base channels I may be set in place, levelled, and bolted down. Then, starting at any desired point, a wall column 3 may be set up and bolted to the and holds the upper ends of the wall columns 3 in line. It-consists of an outside member H which 10 I prefer to form of steel pipe of suitable size,an inner member l9 which'rests on the column top channels 6, and for which a rolled angle is a convenient section,'and a number of flat steel latticebars 20 arrangedtobrace'the members l5 l8 and I9 together. The member I is welded to theouter ends of the various channels 8, and the member ID is welded to their inner ends to formatruss.
.Themembers l8 and Mean be made in con- :0 venient lengths and welded end to end. If the truss ll is fabricated in the shop it can be made in about 10 sections for the floor plans of Figs. 1 to'4. and if made in the field it can be made of any convenient lengthsot material.
, When the truss I 'I is welded to the tops of all the wall columns 3, the bases of these columns can then be welded to the base channel I. At this point we have arigid steel structure to the eaves, and with the wall slabs i5 loosely in place.
In the design shown in Figs. 2 and 7 the eight central columns 26 carry "practically the entire weight of the roof if the same is formed by a preferred method to be described later, and these columns and their foundations may be designed accordingly. To show the flexibility of the sys-'- term I have shown in Figs. 3 and 4 other floor plans using the same outer walls and wall columns as shown in Fig. 2.
One of the main features of the present invention is the use of a roof built on the contour of a catenary curve.
According to the books "the'catenary is the curve assumed by a perfectly 'fiexible cord when its ends are fastened at twopoints. the weight of a unit length '0! the cord being constant"-- 1. e. uniform.
Fig. 6 shows three separate catenary curves (approximated by circular arcs) all assumed to be supported from the common points A and B. The uppercurve A C" B is shallow and similar to the curve used in suspension bridges. The lower curve A C B is a deep one similar to that used for suspended coal bunkers. The intermediatecurve A C D B is one suitable for the roofs of small buildings.
It will be noted that in any of these curves, the stresses at the points C, C, or C" are horizontal. In the curve A C D B, if a support be placed at the point C, and one at the point D, the portions A C and D B may be eliminated, and only the portion C D used for the roof in hand. This portion of the curve is the one used for the rafters shown in Fig. '1.
All the points of the catenary curve may be figured mathematically, including the stresses for assumed loads, butthe formula is complex, and for all practical purposes there is an easier method. Considering one side of Fig. 7, the roof has a rise of one half its span.
In Fig. 6 it will be evident that if the points C and D represent the position of the cave and ridge of a proposed roof to a full size scale, a cord may be stretched over them tightly in a substantially straight line as shown dotted. If the tension of the cord is gradually reduced, the cord will assume a variety of curves, each one of them being a true catenary, until a curve such as C E D is reached. However curves much below the curve C D are not suitablefor drainage. The desired curve to please the eye may be thus selected for small roofs in a few minutes.
Now it is also necessary to know the stress in the cord in order to design the rafters or trusses. This may all be calculated by abstruse mathematical formulae but here again a simple method is available. In order to obtain the tension in any given catenary, a chain of known weight per foot may be stretched to the desired curve, and its tension measured by a spring balance or other means, from which the tension due to any uniform load may be easily calculated.
However the loads on a roof are not uniform.
'- The roof must be strong enough to support I in any other type of roof. In the roof of Fig.
7 the snow will probably lie deepest at the lower portion of the curve, and the wind pressure will be greatest at the upper portion of the curve.
In order to provide for these varying conditions I prefer to make use of a pair of catenary tension members one above the other, and connected by bracing one to the other. thus forming a trussed rafter or small roof truss.
In Fig. 7 the upper catenary tension member 21 may pass over a ridge pole or pipe 90, and be welded at each of its ends to one of the pipes IS on either side of the house, and also to the ridge pole 30. The lower catenary tension member 28 may also have its ends welded to the side pipes l8, and its middle portion supported by a pair of ridge poles 3i, and the three ridge poles 30 and 3| may be connected by welded lattice bars to form a triangular truss. This construction is merely illustrative of a variety of suitable details.
The lattice bars 29 may have their ends welded to each other and to the members 21 and 28. The assembly of the members 21, 28, and 29 will be much lighter for an equal span and equal loads than a beam, because the principal or dead load stresses in the members 21 and 28 are normally pure tension, as compared to the flexural stresses in a beam.
Either the members 21 and 28 may be of equal section to divide the load, or the upper member 21 may be designed to carry the full load, and the lower member 28 may be made only strong enough to avoid distortion of the upper member 21 from the catenary curve when the rafter is subjected to uneven loading. As
- long as the loading is uniform and the upper member 21 keeps its true catenary contour the stresses therein are purely tension.
To support the ridge poles 30 and 3|, I provide a series of A frames 32 resting on the eight central columns 26 of Fig. 7, and on the end outside wall columns 3 in line therewith, if 'the roof slopes only to the side walls.
, If the roof slopes both to the ends and sides of the house, I provide additional corner ridge poles 34, 35, 36, and 31 as indicated in Fig. 1, and which are supported at their outer ends by the pipes l3, and at their inner ends by one end of the ridge pole 30. Since this design is for a welded assembly, I prefer to use common steel pipe of suitable sizes for the members I8, 30, 3|, 34, 35, 36, and 31, as affording easy connections for the flat bar members 21 and 28, and being easy to weld to each other.
In order that each rafter may have the catenary form, the members 34, 35, 3B, and 31 must be bent to a curve which will be the intersection of the side catenary roof slope and the end catenary roof slope, which may be duplicate or different curves, and each member 34, 35, 3B, and 31 may be built as a truss similar tothe members 21 and 23.
As the rafters in this case are of different lengths, the construction will naturally be more expensive, and it is for the'builder to determine whether the enhanced appearance is worth the additional expense, Just as with a roof framed of wood.
It is also to be noted that if the full length rafters 40 of Fig. 1, are bent to a true catenary, the shorter rafters may not be a true catenary, but they will be close to one, and this is of no particular importance, as these rafters are trussed, and carry a lesser load than the full length rafters.
The assembled rafters of Fig. 7 may be designated as a whole by the numeral 40, and may be spaced from two to four feet apart depending on the type of sheathing used, and various building codes in cities. As sheathing to span the spaces between the rafters 40, wood, metal, or various composite materials may be used.
For this purpose I prefer steel as being both light and strong, and because of its stiffness corrugated steel is ideal for the purpose. Such sheets are specifically designed for roofing, to be laid on spaced purllns with their corrugations running down the roof slope. When so placed and lapped they are rain proof. However, for the present invention, the sheets are placed with their corrugations running horizontally, or at right angles to the rafters 40. In such position they span the spaces between the rafters 40 efiiciently, and being flexible parallel to their corrugations, they may be readily bent to the roof curve.
The sheets 38, so laid may be bolted, clipped, or spot welded to the top rafter member 21. Above the sheets 38 I prefer to use a sheet .copper cover 39, which may be fastened to the sheets 38 by small rivets. The combination of the steel corrugated sheathing and the sheet copper cover gives a roof which is light, strong, water, wind, and fire proof, very durable, and of good appearance.
It is obvious however that practically any usual type of roofing materials may be employed; as
. positions are .notsumciently "fire resistant, and
tional in shape, theplans seem to applicant to shingles, tile, slate, or various, composition roofings. Woodshinglesandthe varioustarred com- 4 slate or tile cause needless weight ata point where it does the most damage during an earthquake.
' 'At 14 I show braces from thetop of the out- 7 side' walls to a central pointof certain of the rafters 140. All these bracesmay be or flat steel bars or light 'angleswithwelded connections, and
may be applied wherever needed almost as easily as a wooden brace may'be cut and ,nailed.
The whole oi the housema'y be provided with a ceiling at'the level of the eavesgor certain rooms may be celled at. the rafters. For, the first caseI prefer to'us'e a suspended'ceiling constructed 'as follows: A
Theangle i9 extends entirely aroundjthe house.
The interior partitions may be built to' an equal height and capped'with a flat bar welded to, the
topsof the interior columnslor studs. Upon these members and welded thereto, there may be placed a series of small flat bars, say x 1 in section or evensmaller, andspaced about two feet apart. Instead of fiat bars, the members 43 may be small angles or channels, or the upper and lower members 43 may beany desiredc'omblnation ofiilat bars, angles, or channels. 7
In the design of Fig. l'the'se bars should be set diagonally, or at an angle of 45 degrees with l-he'outer walls, and all the bars should be welded to each other at their various intersections, thus forming a net or mesh similar to wire netting.
the rafters 40.
To support these bars between the partitions I "providevertical tires 4| of fiat steel, say x in section, the upper ends of. these ties being welded to the lower member" of therafters l0, and their lower ends being welded to the upper sides o'f the ceiling bars 43J'There maybe a tie 44 at each intersection or the bars 43, and the ties may be" inclined to meet'the rafters 4!! where necessary. v
If a plasteredceiling is desired, metal lath may be wired, clipped, or welded to the bars 43 to receive the plaster. I prefer however touse some form of wall board or asbestos sheeting, which may be fastened directly to "the under sides of the In certain cases it may be desired, for architectural effect,'to place the ceiling just under It will -benoted that sincethe tensilestresses in the catenary' rafters are practically-horizontal at the eaves, substantially the whole weight of the roof of Figs. 1 and 7 is-carried bythe central inside wall columns 26,-which with their foundations must be designed accordingly.
The rectangular houses 'of Figs. 1, 2, 3, and 4 have iii-panels of 4 ft. each,*or a-wall periphery of 144 linealfeet and the'enelosed gross area with a wall 6 thick is 27.51: 43.5 or 1196sq."it.
The elliptical houseof Fig. 3 may also have 36 panels of 4 ft. and'the same wall peripherary of 144 ft., but the gross enclosed area-here is approximately 1560 sq. ft. passing; that it is not necessary "to use, a true ellipse, as a close approximation may beobtained by the use of four connected circular arcs; which areeasier to layout.
The circular house of Fig. "G'may also have 36.
panels of 4' ft. and a wall peripheryof 1.44 ft., but here the grossenclosed area is 1626 sq. ft.
with 6" walls, or .a gain of 430m. it. in usablearea with the same expense for the enclosing wall.
This isa g'ainof over' 36%.
a While the rooms of Figs. 3 and 4 are unconvenacross the building.
It mayv benoted in show equal utility and convenience, and a distinct efficiency will occur in the rafters becausethey are not parallel. The corrugated sheathing 38, and the copper covering 39 will also be cut' to some waste of material. i
Let us now pass from the details or bungalows features ofQthis'inVentiOn, viz.the c'atenary roof.
The simplest'form of catenary roof is a metal sheetsuspendedby two of its ends or edges to hang in a catenary curve, and combined with similarsheets to cover a desired area; Such a construction is ,indicated diagrammatically in Figs. 15 and 16, inlwhich such sheets are1sup ported between adjacent rbof trusses 59, Iorming -a flat shallow trough between the trusses "which should be slopedtoward the outer walls of the building for drainage. In sites where there were no winds, such an arrangement might be suitable, without any bracing forthe roof sheets-60. But such'lo'cations are rare.
Now ifat intervalsol three toiive feet, light flat bars 6| are suspendedunder the sheets 60 and in parallel relation thereto, such bars may be connected directly to the sheets Giiby welded lattice bars 62, to stiffen the sheets.
tion could be used with bays of say 20 feeigand using standard or usual columns and roof trusses;
the usual purli ns and corrugated sheet roofing being eliminated, and replacediby the suspended catenaryroof sheets Gland the bracing members 6] and 82.
4 m t 01' this kindwould certainly lighter.
tha'nthe usual construction of purlins and corrugated sheets, as the purlinsare necessarily strong enough toresist fiexure, as are also the. corrugated sheets This is'the prime reason: for corrugating them. I: the other hand the catenary sheets Gil and the brace bars. flare in puretension when under uniform loads. e
A further application" of this'principle for buildings of wide span is indicated i Fl .;17, which will in a sense eliminate roof trusses. In this case th-usualsteel building columns 63 could be used, having a continuousbeam or truss 64 running along their tops. This member would take both. vertical, and horizontal. loads Between each pair of opposite columns 63, ajhorizoritalcompression member, isplaced, to span From the upper surfaces oi the opposite trusses 64, the roof .sheets 66 may be stretched, and between the roof sheets 66 and each of manta. zontal compression members 65', spaced verticalties 61 may be placed. These may either be threaded rods with nuts, or welded ties as previously described. I
This construction formsla truss in which the top member is in tension and the bottom member in compression, being the exact reverse of usual practice. In this case also, the weight of the to a wider consideraionof one-of the principal" In thisway a standard m building construcmembers 65 and 61 is supported by the roof sheets 66, and the tension of the sheets 66 is balanced would not be a true catenary, but could be made to approach this curve to any desired degree by closer spacing of the tie bars 61, or by branching them as indicated at 6!. Such a roof being fairly flat, would not be affected by ordinary winds, and snow loads would be fairly uniform. It is thought that roof spans of 100 feet or more may be practical with this system, and that proper calculations will show a considerable economy in material.
In roofs of the type shown inFlgs. 5, 15 and 16, the most practicable material for the roof sheets 60 and 66 is steel. The sheets could have adjacent edges lapped'and welded. They should be of copper alloy steel, or othernon-corrosive metal. For the cover sheets 39 of Fig. 7' copper sheets are the best, but very likely a copper alloy or brass sheet would be good enough and cheaper.
To summarize, a roof employing the catenary curve, with the sustaining members in pure tension under uniformly distributed loads, may fall under any one of the following five general classes:
-1. The roof may consist of a single sheet of metal or other material, stretched in a catenary curve, and being self supporting under its own tension.
2. The roof may consist of a metal sheet'as above, and having attached spaced catenary braces to take eccentric or non-uniform loads.
3. Instead of the covering sheet being selfsupporting as in 1 and 2, the same may be supported on catenary rafters or tension members, with interposed sheathing, and such rafters may either have sufficient stiffness in themselves, or be braced or trussed, to carry non-uniform loads.
4. The roofcovering sheet may be a composite member such as a concrete slab with steel reinforcing bars, the slab being laid in a catenary curve with the reinforcing bars adapted to take the tensile stresses produced by the weight of the slab. Various other forms of composite roof covering may be used, such as'asbestos sheets containing steel wire mesh. The essential requirement is that the'roof covering be wind and water tight, and that it be laid in a catenary curve or one substantially similar thereto, and that the covering sheet, or its supports possess sufficient strength for safety.
5. The roof of a large building may be subdivided into sections, of which each section is a separate unit partaking of the characteristics of some of the above classifications, or combined with older forms.
Having now set forth my invention in various preferred forms, and in such detail that those skilled in the various related arts may apply it, I claim as my invention:
1. In a building structure, supporting members such as columns or walls, a roof comprising a sheet of material adapted to resist tensile stresses, the said sheet being suspended in the form of a catenary curve, and continuous bracing means extending from one sheet support to the other, to prevent distortion from the said catenary curve.
2. In a building structure, supporting members such as columns or'walls, roof trusses supported thereby, a roof comprising a sheet of ma-- terial adapted to resist tensile stresses, the said sheet being suspended in sections between adjacent roof trusses in the form of a catenary curve,
and a continuous lattice for bracing the said roof sheet against distortion from the said curve.
3. In a building structure, two lines of parallel building columns, a truss extending along the tops of the said columns and adapted to resist both horizontal and vertical stresses, roof sheets adapted to resist tensile stresses stretched across the building and secured to the said trusses, compression members extending across the building below the said roof sheets and between opposite building columns, and tie rods connecting the said roof sheets and the said compression members to support the latter.
4. In a building structure, supporting members such as columns or walls, rafters spanning the said supports, each of the said rafters comprising a pair of tension members spaced apart. vertically, and curved to the contour of a catenary, bracing members connecting the said catenary tension members to obtain rigidity, and a roof covering supported directly on the said rafters.
5. A steel frame for a building structure, comprising in combination outside wall columns, a ridge pole, catenary rafters supported by the above two elements, the said rafters each being composed of two flat bars in substantially parallel relation and connected by lattice bars, and corrugated steel sheathing secured to the said rafters with its corrugations set horizontally to support a weatherproof covering.
6. A steel frame for a building structure, comprising in combination outside wall columns set in a continuous curve, inside wall columns in supporting relation to the roof, a continuous truss supported by the said outside wall columns, and adapted to resist both horizontal and vertical stresses, and a roof carried by said inside wall columnsand by said truss and which in vertical section has the contour of a catenary curve, and in which the supporting members thereof are in pure tension under uniform loads due to their catenary contour.
7. In a building structure, roof supporting members, transverse roof trusses supported thereby, a roof sloping both ways from a ridge extending lengthwise of the structure toward the sides thereof, the said roof comprising sheet material adapted to resist tensile stresses, and hung in sections secured to adjacent roof trusses, each section being hung in the form of a catenary curve extending from one roof truss to the next, the upper surfaces of the said roof sections forming wide shallow troughs extending across one half the width of the structure and the said sheet material being curved in one direction only.
8. In a building structure, supporting members, a horizontal truss or plate extending along the tops of certain of the said members, a ridge pole supported by certain of said members, catenaryrafters spanning from the said ridge pole to the said plate, a roof covering over the said rafters and supported thereby, a series of criss-cross bracing bars extending horizontally to cover the area enclosed by the said plate, and secured to the said plate to brace it against the pull of the catenary rafters, and tie bars connecting the said rafters and the said cross bars to support the latter.
9. A fabricated steel rafter for building structures, comprising in combination an upper member in the form of a flat bar, and which is bent to form a catenary curve, a lower member also in the form of a flat bar, and bent to a catenary curve substantially parallel to the curve of the upper member, and flat lattice bars connecting the said upper and lower members to obtain rigidity.
10. A fabricated steel rafter for building structures, comprising in combination an upper member in the form of a flat bar, and which is bent to form a catenary curve, alower member also in the form of a flat bar, and bent to a catenary curve substantially parallel to the curve of the upper member, and flat lattice bars having their ends welded respectively to the said upper and lower members, and with their respective edges adjacent to the edgesof the said upper and lower members.
11. A fabricated steel rafter for building structures, comprising in combination an upper member in the form of a flat bar, and which is bent to form a catenary curve, a lower member also in the form of a flat bar, the same being bent to a catenary curve substantially parallel with the curve of the upper member, and flat lattice bars connecting the said upper and lower members to form a rigid structure, the said upper member being proportioned to support all uniform loads, and the said lower member being proportioned to take such eccentric loads as may reasonably be expected to be placed on the roof.
12. A fabricated steel rafter for building structures, comprising a non-flexible bar having upper and lower flanges and a central portion connecting the said flanges, the same being bent to of a triangle, lattice bars connecting each of the said members with two of the others, sup ports for the said ridge pole, and catenary rafters extending from the said ridge pole to an eave of the roof.
14. In a building structure, roof supporting members,
roof covering comprising sheet material adapted to resist tensile stresses, and hung on the said rafters in parallel catenary shaped troughs extending from rafter to rafter, to cover the space below the rafters.
15. In a building structure, roof supporting members, a ridge pole, straight parallel rafters extending from said ride pole to an eave of the roof, and being sloped for drainage, and a roof covering comprising sheet material adapted to resist tensile stresses, and hung on the said rafters in parallel catenary shaped troughs extending from rafter to rafter, to cover the space below the rafters.
WALTER W. MACFARREN.
I straight parallel rafters supported thereby, and being sloped for drainage, and a