US696838A - Concrete-arch construction. - Google Patents

Description

No. 696,838. Patented Apr. I, I902.

w. c. PARMLEY.

CONCRETE ARCH CONSTRUCTION.

(Application filed June 4, 1901.)

(No Model.) 3 Sheets-Sheet l.

WITNESSES: MIME/Wok. zm Lu/ By A2121. ATT'ORNEY.

TNE uonqls PETERS c0. we re-Luna, WASHINGTON. a, c

No. 696,838. Patented A' r. I, |902..

w. c. PARMLEY.

CON CRETE ARCH CONSTRUCTION.

(Application filad June 4, 1901.)

(No Model.)

3 Sheets-Sheet 2.

' ATTORNEK rm: nunms PEYERS co, mom-urns wuummom by c.

No. 696,838. Patented Apr. I, I902.

W. C. PARMLEY.

CONCRETE ARCH CONSTRUCTION.

(Application filed June 4, 1901.) (No Model.) 3 Sheets-Sheet 3.

v WITNESSES: MjWI INVENTOR. BY 1 ATTORNEY.

NrTnn STnTns PATENT rrrcn.

\VALTER O. PARMLEY, OF CLEVELAND, OIIIO.

CONCRETE- ARCH CONSTRUCTION.

SPECIFICATION forming part of Letters Patent No. 696,838, dated April 1, 1902.

Application filed June 4, 1901.

To all whom, it may concern:

Be it known that I, WALTER O. PARMLEY, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Concrete-Arch .Ooustruction; aud'I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in the construction of arches, vaults, and sewers, &c., and in particular to such as are constructed in Whole or chiefly of concrete or cement mortar, although also applicable to such constructions When built of masonry or partly of masonry and partly of concrete.

The object of my invention is to gain increased strength in such construction and also to diminish the amount of material used, and thus secure reduced cost of construction combined with increased strength. These objects I accomplish by the method of construction and the arrangement and combination of materials hereinafter described, and illustrated in the accompanying drawings, in which-.-

Figure 1 represents in vertical section an arch strengthened by embedded tensionstrips in the intrados and extrados of the arch, the abutments of which arch may be continued into any desired structure-such, for instance, as a complete circle or oval forming a sewer or analogous tubular structure, as shown in Fig. 2-or may end in pillars or be otherwise suitably supported, as shown in Fig. 3. Fig. 4 is a transverse section similar to Fig. 1, but shows a modified arrangement of the tension-strips, wherein a continuous strip on one side and discontinuous strips on the other side of the arch are employed in the reverse arrangement of that shown in Fig. 3. Figs. 5 and 6 represent vertical sections through cylindrical structures, such as sewers 0r sewer-pipes, exhibiting the arrangement of tension-strips in such constructions. Fig.

7 represents a partial section through the crown of the arch shown in Fig. 1 or Fig. 10, the plane of section being indicated by the broken line a: 00 in Fig. 1 and showing the relative arrangement of the tension-strips in Serial No. 63,090. (No model.)

trated in Figs. 2 and at. Fig. 10 represents,

diagrammatically, the arrangement of tension-strips placed alternately in intrados andeXtrados to meet all possible conditions of load or strain. Fig. 11 represents the arrangement of the tension-bars in such an arch as shown in Fig. 2 or 10 when the point of loading and the strains due to it are known. Fig. 12 represents the combinations of tension-bars in a similar structure in a case Where continuous bars passing through all the tensional regions are alternated with bars in the intrados in a single tensional region only. Fig. 13 represents a sewer or analogous arched structure subjected to vertical load only and having the alternating bars passing through tensional regions in both intrados and extrados, and its upper part shows the arrangement of the barsin a segmental arch whose abutments areindicated in dotted lines.

In all the figures, A indicates bars in the intrados. trados of the arch.

In the construction of concrete arches, &c., strengthened by metallic embedded strips the important consideration is to obtain the maximum strength of construction to resist compressive or crushing strains with the smallest amount of material. I am aware that it has before been proposed to strengthen concrete arches by metallic strips, bars, or similar materials embedded in or near the intrados or extra-dos of the arch; but in such cases the arrangement of the embedded bars has not been such as to secure the greatest strength for the amount of material used in the arch. In an arch such, for instance, as that shown in Fig. 3 or i a weight or crushing force applied upon the crown of the arch at the point indicated by m produces at that point a compression of the materials forming the eX'trados of the arch and correspondingly induces a tensile strain upon the materials forming the intrados of the arch at the point marked 0. To resist this tensile strain tending to separate the materials forming the intrados of the arch at the point marked 0, I locate in the B indicates bars located in the exmaterial at that pointby embedding therein as the constructionproceeds metal bars, rods, strips, or plates, which bars, 850., may be plain or corrugated, angled, or formed of any desired shape, and which by the tensile strength of the metal strongly reinforce the arch and enable it to withstand loads and strains tending to exert such tensile strain upon the intrados. The most economical use of materials to secure a given strength is obtained by placing the embedded tension-strips so as to pass through the points of. tension and so far beyond the same as to secure firm anchoragein the parts subject to compression and generally relying upon the concrete chiefly or wholly to sustain the compressive strains. In order to accomplish this end, it is necessary to know approximately the location of such points of tension and compression in the proposed structure and to adjust the embedded strips or bars in such relation to the entire mass of the arch as will effect/the above object. To do this of course necessitates a knowledge of the strains to which the structure when completed will be subjected, and where in any given structure the direction of greatest pressure or strain which it will have to resist is uncertain the preferable arrangement of the embedded strips or bars will be such as to meet all the emergencies to which the structure may be subjected, and in any such case it will be desirable to provide for resistance to tensile strains which maybe exerted in different 10- cations. In an arch the tensional strain induced at o in the intrados by load applied on the crown of the arch at m in the transmission of the load strains to the abutments is transmitted to the extrados at the haunch, as at 0, and again to the intrados at or near the springing-line, as at 0 and the compression strains in like manner suffer an opposite reversal and appear at m m An embedded bar, rod, or strip extends its strengthening effect upon the concrete throughout an annular area surrounding such rod or bar. Hence when embedded near the surface of the concrete mass its effective area of strengthening effect is substantially semicircular and extends to a distance from such rod depending in great measure upon the cross-section area of the rod or bar. Thus when bars are embedded in an arch vertically above each other the areas of effective strengthening due to the two bars are separated by a lateral wedge of material on each side of a pair of bars to which such effect does notextend. Tosecurethenecessarystrengthening effect in a broad arch with bars so disposed requires, therefore, the placing of the pairs of bars near together, thus making the cost of the structure large. In contradistinction to this I prefer to place the bars in such constructions as require the use of tension bars in both intrados and extrados in such a manner that those in the intrados alternate in vertical disposition with those in the exin pairs one vertically over the other. In this manner the tension on the arch is: effectively resisted by the metal bars whether the force or pressure tending to crush thearch is greater in the vertical or horizontal direction, and by the alternate arrangement of the tension-bars each bar becomes the strengthening nucleus of the greatest mass of surrounding concrete, and thus affords the best means of transferring the tensile strains in the metal bars through the compressive strength of the concrete to the abutments or to the anchorage.

Another disposition of the tension-bars in cases where the load or strains to be supported is known is shown in Figs. 2, 5, S, &c., in which a-single bar, rod, or plate is so disposed as to pass through all the point of tension in an arch subjected to load, producing vertical pressure, and thus passing alternately near the intrados and eXtrados and through or near the neutral points between the areas of compression and tension. Each bar th us performs all the useful functions of two bars one vertically above the other. The disposition ofthe tension bar or strip in a substantially circular structure-such, for instance, as a sewer or pipe-is shown in Fig. 5, which represents the position of the rod or bar when the load or crushing strain is applied from above. In case the strain or crushing force were to be applied laterally the disposition of the tensionbar would be such as would be represented by Fig. 5 if it were rotated ninety degrees, the tension-bar then being at the top of the extrados and at the inner part of the sides. Obviously by alternating the tension-bars which thus pass through the tension-points of both intrados and eXtrados in the manner indicated in Figs. 7, 10, and 13 all the benefits of that arrangement and those due to the peculiar disposition of the bars with regard to the tensional regions are secured in the single structure.

The benefits of the construction above described and illustrated in Figs. 2, 8, 10, and 13 may be obtained in great degree by locating a tension-bar at the tensional regions only in the intrados or extrados, extending so far beyond each such region as to afford a sufficiently firm anchorage in the concrete and to place a continuous bar extending through the opposite side of the arch, as shown in Figs. 3, 4, 6, and 9. In such construction the bars in opposite regions-that is, in intrados and extradosmay be placed in the same or different vertical planes, as preferred.

Figs. 4, 9, 850;, show the metal bars as arranged to sustain the tension in continuous or groined arches. The tension is a maxiportions. or alternately with the continuous bars mum at the points marked 0 0. In the case of groined arches the tension-bars may pass along the line of the groin or transversely with the axes of the arches. In certain cases it is desirable to place one line of continuous metal bats along the intrados and place discontinuous bars along the extrados at those points only where tension occurs, allowing said bars to extend far enough into the concrete on either side to form sufficient anchorage. This arrangement is shown in Figsu3 and 6, where a continuous bar is shown at A and discontinuous bars at B B. In other cases this order might need to be reversed in the manner-shown in Figs. 4 and 9.

Other cases occur in which by disposing the bars as shown in Fig. 2a portion of the intrados on either side of the crown of the arch may not be sufficiently supported without placing the bars nearer together than is required for the adequate support of the other In such cases by introducing near shorter tension-bars in the intrados, as shown in Fig. 12, extending along the intrados and sufficiently on either side of the region of maximum tension to afford proper anchorage the required strength is obtained without usingmore than the minimum amount of material. i

In still other cases where it is desirable to retain the disposition of bars shownin Fig. 2 it may be desirable in view of the uncertainty which may exist as to the pressure and the support which the arch will receive at the haunch, owing to change of conditions-such as unequal settling of theground, &c.to supplement the bars shown in Fig.2 with bars passing through the intrados at the crownand then passing gradually through the arch, as shown in Fig.5, and along the extrados in the regions of tension near the springingline. Such an arrangement is shown in Fig. 13. Another modification may be effected by combining in alternate arrangement, as shown in Fig. 7, the bars A of Figs. 1, 3, and 6 with the bars shown in Fig. 5, resulting in the arrangement shown in Fig.

11 or the upper part of Fig. 13. These forms are chiefly useful in embedded arches or v arches of low rise.

In the claims I use the word bar as a generic term, intending thereby to include rods,

plates, Webs, cabled or built-u p bars, or metal shapes or any kind analogous to bars, strips, or rods.

hat I claim as my invention is- 1. A concrete arch having embedded therein metal bars which extend continuously throughall the regions of tension in intrados or extrados of the arch, and otherbars which extend through part only of theregious of tension in either intrados or extrados, substantially as described.

2. A concrete arch having embedded there in metal bars which extend continuously through all the regions of tension in intrados or extrados of the arch, and other bars alter:

nating therewith, which extend through part only of the regi'onsof tension in eitherintrados or extrados, substantially as described.

3. A concrete arch having metal bars embedded therein,both in intrados and extrados, at the regions of tension and extending continuously through the regions of tension and sufficiently into the ab utments to obtain a se-' cure anchorage, the bars in the extrados being opposite the spaces between'thosein the intrados.

4. A concrete arch having embedded therein metal bars which pass continuously through all the regions of tension in bothintrados and extrados and other bars extending through part of the tensional regions only and far enough beyond to give secure anchorage.

5. A concretearch having embedded therein metal bars which pass continuously through the regions of tensionin both intrados and ext-rados and'other bars alternating therewith and extending through part only of the tensional regions and far enough beyond to give secure anchorage.

6. A concrete arch having embeddedtheie in metal bars which pass continuously through the regions of tension in both intrados and extrados and other bars which extend through a single tensional region and far enough beyond to give secure anchorage, the

bars of one set being opposite the interspac'es between the-bars of the otherset.

Kid

In testimony whereof I hereto affix my signature in presence of two witnesses.

' WALTER O. PARMLEY'.

Witnesses:

J. F. I-IERRioK, MYRON B. VoRoE.

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