US2971295A - Prestressed concrete units and structures - Google Patents

Description

5 Sheets-Sheet 1 O. B. REYNOLDS PRESTRESSED CONCRETE UNITS AND STRUCTURES NVENTOR. O. B. REYNOLDS AT TORN EYS Feb. 14, 1961 Fild March 21, 1955 Feb. 14, 1961 o. B. REYNOLDS 2,971,295

PREsTREssED CONCRETE UNITS AND STRUCTURES Filed March 21, 1955 5 Sheets-Sheet 2 INVENHM.

3 O.B.REYNOLDS AT TORNEYS Feb. 14, 1961 o. B. REYNOLDS PREsTREssED CONCRETE UNITS AND STRUCTURES Filed March 21; 1955 3 Sheets-Sheet INVENTOR.

O. B. REYNOLDS ATTORNEYS .costly procedure.

and remove the old foundation.

. structure or unit to another.

PRESTRESSED CONCRETE ANI) STRUCTURE Urvel B. Reynolds, Bartlesville., Qkla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Mar. 21, 11955, Ser. No. 495,717

6 Claims. (Cll- 513-133) lThis invention relates to stressed concrete units or formation of stressed `concrete structures. A specific aspect of the invention pertains to portable stressed Afoundations or supports for heavyequipmment, such as oil well pumping units and powerrplants, and to means for attaching `such equipment to such `a foundation.

There is a need for stressed concrete structures in various branches of industry. A notable application is in the production branch of the petroleum industry where heavy pumping equipment is utilized j in pumping oil wells. lt is conventional to pour the concrete base or foundation for the pumping unit and power plant as a single concrete block at the well site. When it rst becomes necessary to pump an oil well it may be desirable to install a large pumping unit to produce the maximum allowable amount of oil whilelater in the producing life of the well a small unit will suice. On lthe other hand, only'a small unit may be requiredto pump the well early in its life when it produces clean oil, while alarger one is required later when it becomes necessary to pump alarge `volume of water with the oil. The latter condition arises in the operation of water-drive reservoirs or reservoirs which are artificially ilooded withtwater. In either instance it has been `necessary `in `the past to build forms and pour two separate foundations :which is a `very Neither foundation can be salvaged but an `additionalexpenditure. mustbe. made to destroy Thus thereis a need forr portable concrete units which `can be assembled into a unitarystructure or foundation at the well site and which can be disassembled at any timefor transport `to a new location. Through the practiceof the invention it is Vpossible not only to provide lfoundations at a much lower initial cost but also to t provide foundations which can be removed easilvand can be reused at new locations.

The invention is applicable where any load-supporting structure is desired and, particularly, wherejt'he need for movingthe structure to a newlocation `after a period of` useexists. The supporting structures of the invention have utility as supports forv any heavy machinery or equipment and other loads.

The principal object of the invention is to provide `stressed tconcrete `units adapted `for constructingnstressed load-supporting structures. Another object is .to `provide stressed concrete load-supporting structures constructed `of individually stressed concrete units. Another object is to `provide means for stressing load-supporting concrete structures comprisingindividually stressed segments or units. A further object is `to provide portable` stressed conceret structures. Anotherjobject of `the invention is to provide means for attachingone stressed concrete It is also an object of .the invention to provide improved `means for` `attaching heavy equipment to a stressed concrete support or foundation. Other objects of the invention will become apparent from -a consideration of the` accompanying disclosure.

The invention provides` individually stressed `.concrete Patented Feb. 14, 1961 supporting structure which is adapted to be stressed as a unit by post tensioning during assembly of the structure. It is practical to build the units from which the structure is to be assembled as large as possible, bearing in mind that the units must be transported tothe loca.- tion where the structure is to be utilized. Because of the size and weight of the concrete units, they are subject to breakage during handling and must be stressed to avoid breakage prior to stressing the entire structure into which they are to be built. It has been found that units comprising concrete slabs weighing several tons can be transported and handled by heavy equipment without breakage of the slab when the same is properly stressed prior to transport. It is also possible and feasible to construct large slabs of this `nature of smaller individually stressed units partiallyor completely assembled before transport.

A more complete understanding of the invention may be had from consideration of the accompanying draw ings of which Figure l is a plan view of one type of structure constructed and assembled in accordance with the invention; Figure 2 is an enlarged cut-away section of Figure l; Figure 3 is a pictorial View of section B of Figure l; Figure 4 is a pictorial View of a complete foundation for an oil well pumping unit and power plant for operating same; Figure 5 is a transverse section taken on the line 5-5 of Figurel; Figure 6 is a transverse section taken on the line 6-6 of Figure 4; and Figure 7 is a cutaway view taken at the juncture of runner 40 with block 42. The various vie-ws or figures of the drawings are diagrammatic and corresponding parts are designated with like numerals. l

Referring to Figure l, the structure shown includes a generally rectangular slab i0 comprising sections of individually precast and stressed units A, B, C, D; Etand F, which in the drawing are similarin size and shape, but which are not necessarily so. Each unit is individually stressed with rods extending through the `concrete` longitudinallyand laterally at `substantially right angles to each otherat different levels Vin the unit. These individually stressed rods 12 are Ashown inthe unitfB and `comprise. rods threaded at one or both ends and provided with `the nuts which stress the unit by. post tensioning when tightened so as to apply the desired tension on the rods. If desired 4the rods may be provided with `a large square or hexagonal head on `one end which contacts a bearing plate or washer `recessed `in the concrete. It is` to be understood that each of theunits B, C, D, E and F are provided with `individuialjstressing yrods which are under the desired stressing tension `before assembling the structure.

In order to facilitate `the proper alignment of the units or Sections during assembly, dowel rods or pins 14 are provided in theedges or abutting `surfaces `of each of the units as shown in section B. These dowel rods :may comprise` short metal rods embedded `in the` proper location in the `concrete at the time of pouring and the dov/els thus located titV rather closely into tubular conduits inthe engagingsurface of the adjacent block or unit. Short metal tubes are found advantageous in forming the sockets lfor the `dowels. These metal tubes are fixed in place inthe proper location prior to `pouring the concrete. It is also feasible to coat the outside `of these` ytubes with a grease which permits their removal after the concrete has set thereby leaving a socket of the proper diameter. The dowel structure is shown more fully inkFigure 3.

Slab or structure 10 is assembled `by aligning the various sections by means of dowel pins 1d (or other `suitable means) and then placing rods 16 and t3 `under tension. These rods extend thru the structure from end to end and from side to side so as to` provide stressing for the entire `structure both longitudinally` and laterallysp that the same will withstand the intended load to be placed on the structure. Rods 16 and 18 may be continuous onepiece rodsor they may be made up of sections 20 as shown. In either event a nut 22 and a washer or bearing plate 24 are provided at either end of the rod to provide tensioning of the same after` assembly of the units. ln constructing the various units a recess 26 is provided in the edges of the unit at the locus of the rod. When the rod is continuous and in one piece, the same is placed under tension by tightening up on either nut. When the 4rod is formed of individual sections 20, a coupler 28 is required to properly tension the rod. Coupler 28 is attached to adjacent ends of two sections 20 thereby having the eifect of uniting these two sections of rod. Rod section 20 in unit E may be tensioned by nuts 22 prior to assembly with coupling 28 screwed up against the nut but this is not essential and nut 22 may be omitted where a coupling is used. Y

In another arrangement of the stressing rods for the entire unit where the rod extends through several units as through D, E, and F, a rod may be extended through two or more-units, as shown, before a coupler is attached. In this manner the length of rods used may be kept close to an optimum length for convenience in handling and construction. Generally, the same arrangement of stressing rods should be used throughout the structure.

The coupler rod and nut arrangement is shown more clearly in Figure 2 ywhich is self-explanatory. In the arrangement shown rod 20 in section E is under tension from nut 22 and washer 24 prior to assembly and coupler 28 is tightened against nut 22. Rod 20 in section F is then screwed into coupler 28 to meet rod 20 in section E and the nut on the opposite end of rod 2t) in section F is turned so as to place the desired tension on the rod. The same procedure is followed with rod 20 in section D.

In forming the stressed units, rods 12 are properly 1ocated in the form in which the concrete is to be poured. These rods are provided with a coat of plastic material, such as grease, soft wax, or paraffin, which does not mix with the concrete and which permits longitudinal movement of the rod after the concrete has set. This allows placing the rods under tension after the concrete has set for a day or more so as to properly stress the units and guard against breakage of the same during handling and transport. In the structure whereinthe stressing rods 16 and 18 extend through the entire structure, a suitable conduit must be provided in the individual units at the time of pouring so that when the units are assembled in proper alignment the stressing rod can be inserted in the conduit. This conduit may be provided by placing in the form prior to pouring a thin metal tube which becomes a permanent part of the unit. It is also feasible and more desirable in most instances to place in the form for the individual unit a rod or tube of the proper diameter which has been given a substantial coat of grease or other plastic material so that after pouring and setting of the concrete the greased rod or tube can be slid out of the structure to provide a conduit for the stressing `rod which is to be extended through the entire structure. In the type of structure where short rods with couplings are to be utilized, these rods may be greased and incorporated into the concrete units as they are poured and retained there for stressing after assembly, although it is feasible in this instance also to provide conduits in the individual units of the proper size and alignment so that the rods can be inserted at the time of assembling the complete structure. In such case it is necessary to assemble the rods and couplers in some of the units before the units are placed in alignment with each other as described in connection with Figure 2.

Referring to Figure 3, individual stressing rods 12 are shown extending through section B both longitudinally and laterally and recessed in counterbore 12. Conduits 30 extending through section B both longitudinally and laterally substantially at right angles to each other are provided for the continuous or jointed stressing rods 16 and 18 for the entire structure. Dowel pins 14 are shown extending from two abutting faces of section B to provide proper alignment with the adjacent abutting sections E and C. Tubular members 32 in the face of B to be abutted to section A provide recesses or receptacles for the dowels on section A corresponding to those yshown in this ligure.

Referring to Figure 4, the structure, substantially as shown, was designed and constructed to provide a foundation for a large oil well pumping unit and engine for operating same. The foundation comprises a stressed Concrete front sill 36, a similar back sill 38, a pair of stressed runners 40 extending from sill to sill and resting thereon, and an engine block 42. Sills 36 and 38 are stressed both longitudinally and laterally by unit stressing rods 44. Similar stressing rods 44 extend through engine block 42 and runners 40. Runners 40, sills 36 and 38, and engine block 42 were individually stressed prior to transport of the units to the location. The engine` block 42 and runners 40 were stressed as a unit by rods 46 extending through the engine block and connecting by couplers, such as those shown in Figures l and 2, to the individual stressing rods 44 running through runners 40 (note Figures 5 and 6). In this manner the individual stressing rods 44 extending through runners 40 protect the runners from cracking and breakage in transit and handling and also function in stressing the block and runner unit after assembly of same.

It is feasible and desirable in instances -where sills 36 and 38 and the other elements of the foundation are too large or too heavy for available handling equipment to construct these elements of a number of individual stressed units in accordance with the structure shown and described in connection with Figure 1.

When assembling the foundation, two layers of 30# felt 50 were inserted between the runners and engine block and the sills to provide friction between the runners and sills and between the engine block and sill 38. This felt also compensates for any irregularities in the precast concrete units.

A bed is provided for the sills and other units in the structure by excavating and filling the excavation with tive inches of crushed rock and one inch of chat or sand. This bed is leveled to provide a common plane for sills 36 and 38 and also for engine block 42 and runners 40. After assembly and stressing of the foundation, the space between the runners is iilled with sand or chat so that uneveness in the bed is compensated during operation of the equipment. v

A series of grout tubes 54 are positioned in engine block 42 and runners 40, together with the associated structure and elements shown and described in Figure 5 at the proper location for connecting with the attaching framework of the engine and pumping unit. Similar grout tubes 52 and the associated structure and elements shown and described in Figure 6 are positioned at opposite ends of the runners 40 directly above the sills to provide means for securing the stressed engine block and runner unit to the sills while providing attachment means for thepumping unit.

Referring to Figure 5, individual stressing rods 44 extend longitudinally through the runners and are coupled to stressing rods 46 in engine block 42, thereby providing a linkage extending through both the runners and engine block for stressing the combination. The attaching means shown comprises a plate 56 embedded in the precast concrete to which is welded or otherwise firmly attached a bolt or rod 58 extending axially up through grout tube 54 to a level just below the top of runner 40. Grout tube 54 provides for lateral movement of coupler 60 for aligning purposes. The upper end of rod or bolt 58 is threaded and is provided with a threaded coupling 60 into which a bolt or'stud can be inserted from an opening in the supporting'steelframework of the engine or pumping unit. This arrangement avoids protrusion of stud bolts above the top surface of the foundation with the attendant inconvenience and usual damage in transport of the concrete units.

Referring to Figure 6, similar attachment elements 56, 5S, andtl extend upwardly `throughrsill 38 (or sill 36) directly below the desired location of an attachment bolt. Coupling 60 is free to rotate so that it may be replaced. In order to apply attaching pressure between sill 33 (or 36) and runner 4I), a bolt 62 is screwed into coupler 60 and a nut 64 is turned on to the upper end of this bolt with a section of steel framework 66 of the pumping unit positioned on the top surface of runner 40. In this manner the attaching bolt and nut assembly provides means for firmly holding-runner 40tin place on sill 38 and simultaneously provides an attaching means for the equipment placed on the runner. The engine is attached to the engine block in the manner shown for attaching the pumping unit, wherein frame 66 is bolted to the base. Grout tube 52 provides annular space around bolt 62 which` is convenient in shifting the bolt slightly in order to line up the same with the framework of the equipment.

Figure 7 shows ,a coupler 28 connecting a rod 46 in block 42 with a rod 44 in runner 40, post tensioning the runner-and block as a unit. Rods 44 and 46 are both free to `move inthe concrete to allow` post tensioning.

In the .specicyy embodiment of the invention shown in Figure` 4, `a foundation .was` designed and constructed for alarge oilwellpumping `urlitandengine.- The engine positioned on block` 42 weighed` approximately 2700 pounds and the gear box rating of the unit was 320,000 pound/inches. The unit had a 120 inch stroke and the load on each runner, including the weight of the equipment and the rod load, was approximately 60,000 pounds. Sill 36 comprised a stressed slab9 thick, 4 wide `and 12 long. Sill 38 was constructed similarly in a block or`slab 9 thick, 3' wide and 7 long. The engine block and runners were likewise constructed of individually stressed concrete units of a thickness of 14". The engine block was 4 7% wide and 9' 10i/z" long. The width through the narrow section of each runner was 20 and the runners had a length of 18 9%.

The stressing rods were l" diameter steel rods and the tension placed on the rods was approximately 30,000 pounds each.

Several engine and` pumping equipment foundations similar to that shown and described in connection with Figure 4 have been in operation several months and have withstood the tremendous wo-rk load placed on them without breaking or cracking. These portable foundations were manufactured in a plant a long distance from the well site and were transported by truck and assembled at the well site without breakage or cracking during handling and transport. When the pumping requirements of the well change so that a smaller unit is required, these portable foundations may be disassembled and moved to a new location and a smaller precast, stressed, concrete foundation may be assembled at the well site for operation of any smaller size unit required.

Any or all of the various parts of the foundation shown in Figure 4 may be constructed of small units in the manner shown and described in connection with Figures 1 and 4. However, it is feasible to construct the sills, runners, and engine block in single stressed one-piece units with stressing rods running therethrough in both directions as shown in the drawing, providing suiciently sturdy transport equipment is available for such large pieces. In any event, it is essential to stress the runners to the engine block as a unit.

In constructing the precast units, if desired, the individual stressing rods may be pretensioned in known manner so that when the concrete sets and the tension on the rods is removed, the concrete units are immediately stressed in accordance with the amount of pretensioning.

This method is rusually less desirable than Atensioningthe rods after the concrete has set. It isralso feasibleto utilize tension cables to stress either the precast units or the structure built from them. Cable tensioning equipment and end fastening devices for such cables are commercially available. Cables may be looped in U-form through the units and/ or structure built from same with the loose ends at a common edge of the unit or structure, tensioning pressure being applied to both loose ends.

It `is desirable and advantageous to form the precast concrete units of a light weight mix which has a density of about pounds per cubic foot as compared with ordinary concrete having a density of about pounds per cubic foot. A light mix of this character is formed of one part portland cement, two parts sand, and three parts hollow porous aggregates which contribute to the lightness of the mix. However, the precast concrete elements may be cast from any mixw'nich sets to aunit of suticient strength for the purpose required.

The specific details given herein are merely illustrative and `are not to be construed as imposing unnecessary and unwarranted limitations on the invention. The number of stressing rods included in any unit may vary so long as the strength afforded by the size and number of these units is suicient for the intended purpose and prevents cracking of the units during transport and assembly. Likewise the number and size of the units inany given element or structure may be varied to suit the particular application involved.

I claim:

1. A portable concrete base for an oil well pumping unit and engine for operating same comprising a pair of individually -post tensioned spaced-apart. horizontal concrete runners having a plurality of post tensioning elements extending through same longitudinally Vthereof and having a pair of adjacent outwardly flared ends; a post tensioned engine block abutting the ends of said runners opposite the flared ends having post tensioning elements extending therethrough parallel with those in said runners; post tensioning elements extending through said runners and said block to post tension same as a unit; a pair of generally rectangular flat sills post tensioned by post tensioning elements extending both longitudinally and laterally thereof, both being positioned transversely to said runners, the first under the abutting ends of said runners and block and the second under the ared ends of said runners; several means firmly fastening said runners to said sills each comprising a metal plate embedded in the bottom of said sill having a first bolt attached thereto extending upwardly to a level below the top of the sill and terminating in a threaded end., a threaded coutpling on said threaded end, a second bolt threaded into said coupling from above and extending upwardly through a tubular conduit in said runner, a metal plate on the upper end of said second bolt adjacent the top surface of said runner, and a nut threaded on the upper end of said second bolt tightly against last said plate; and similar means fastening said engine block to said irst sill.

2. The base defined in claim l wherein the plates adjacent the top surface of said runners and engine block comprise a portion of steel supporting frame of said engine and pumping unit.

3. 'I'he base defined in claim l including -a plurality of attaching means for said engine and pumping unit offset from the means attaching said runners to said sills, each comprising a metal plate embedded in lche supporting concrete at the desired locus of attachment; a bolt attached to said plate and extending upwardly through the concrete support to a level below the surface thereof; a threaded coupling on the end of said bolt adapted to receive a threaded bolt inserted through the supporting framework of said engine and pumping unit, the concrete surrounding a substantial upper section of said bolt extending to below said coupling being spaced from Y 7 Y said bolt and coupling to provide substantial radial movement of said bolt.

4. Av portable concrete base comprising in combination a pair of spaced horizontally elongated parallel concrete runners post tensioned by compression elements extending longitudinally therethrough; a horizontally elongated concrete block post tensioned by compression elements extending longitudinally therethrough, one end of said block directly abutting a pair of the runner ends; compression elements extending through both said runners and said block parallel to former said compression elements, each of ylast said compression elements comprising a rod in one of said runners and a rod in said block connected by a coupling element adjacent the abutting ends of said runners and said block, said rods being free to slide in said `runners and said block, post tensioning `said runners and block into a horizontal supporting unit of improved resistance to the weight of a supported unit; threaded elements in said runners and in said block accessible from the upper side thereof for attaching said supported unit to said base; a pair of generally rectangular iiat sills post tensioned by post tensioning elements running therethrough, both being positioned transversely to said runners, the rst under the abutting ends of said runners and block and the second under the opposite ends of said runners; and means rmly fastening said runners to said sills.

5. The combination described in claim 4 wherein the end sectionsA of said runners opposite the abutting ends are flared outwardly to form a broad base for support of the Samson post of a pumping unit.

6. A portable concrete base for supporting an oil Well pumping unit and a power plant for operating said unit, comprising in combination a pair of spaced horizontally elongated parallel concrete pumping unit runners post tensioned by compression elements extending longitudinally therethrough; a horizontally elongated concrete block for said power plant post tensioned by compression elements extending longitudinally therethrough, one end of said block directly abutting a pair of the runner ends;

compression elements extending through both said runners and said block parallel to former said compression elements, last said elements being ,free to lslide in the concrete and post tensioning said runners and block into a horizontal supporting unit of improved resistance to the weight of said pumping unit and power plant; threaded elements in said runners and in said block accessible from the upper side thereof for attaching said pumping unit and power plant; a pair of generally rectangular at sills post tensioned by post tensioning elements running therethrough, both being positioned transversely to said runners, the first under the abutting ends of said runners and block and the second under the opposite ends of said runners; and means iirmly fastening said runners to said sills.

References Cited in the file of this patent UNITED STATES PATENTS f Phillipe June 22, 1886 684,201 Dick Oct. 8, 1901 1,529,895 La Chance et al Mar. 17, 1925 1,666,149 Rosenzweig Apr. 17, 1928 2,128,375 Millard Aug. 30, 1938 2,257,001 Davis Sept. 23, 1941 2,423,695 Falco July 8, 1947 2,538,443 Delvaux Jan. 16, 1951 2,590,685 Coti Mar. 25, 1952 2,611,262 Dodson et al. Sept. 23, 1952 2,780,935 Rumble Feb. 12, 1957 2,786,349 Coti Mar. 26, 1957 FOREIGN PATENTS 195,570 Great Britain of 1923 606,545 Great Britain of 1948 685,131 Great Britain of 1952 711,449 Great Britain June 30, 1954 713,211 Germany of 1941 939,124 France Apr. 19, 1948 1,069,950 France Feb. 17, 1954

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