US3219224A - Elevated tank support - Google Patents

Description

N 1965 E. ANDERSON ELEVATED TANK SUPPORT 2 Sheets-Sheet 1 Filed July 9, 1963 LLOYD E. ANDERSON GREEN MCALL/$TER& M/LLER ,11 .J Ei/ (9'. 1

H/S ATTORNEYS Nov. 23, 1965 E. ANDERSON ELEVATED TANK SUPPORT 2 Sheets-Sheet 2 Filed July 9, 1963 Fri/ 9. 6

INVENTOR.

LLOYD E. ANDERSON GREEN MCALLISTER MILLER H/S ATTORNEYS United Sttes Patent M 3,219,224 ELEVATED TANK SUPPORT Lloyd E. Anderson, Pittsburgh, Pa, assignor to Pittsburgh- Des Moines Steel Company, Pittsburgh, Pa, 21 corporation of Pennsylvania Filed July 9, M63, Ser. No. 293,667 3 Claims. (Cl. 22tll) This application is a continuation-in-part of my application entitled Tank and Support Structure, Serial No. 838,995 filed September 9, 1959, now abandoned.

This invention relates to single pedestal type storage towers and especially to supporting components of such towers that enable practical ground level assembly of the associated storage tank. Furthermore, this invention relates to supporting components which permit a highly compact and hence functional and attractive overall configuration.

Water towers and other elevated storage tanks have long been condemned for their generally unattractive appearance, which is almost dictated by the structural requirements of suspending a large mass, high above ground level. In recent years there has been a trend toward improving the appearance of elevated tanks by more efficiently employing structural components so as to eliminate the criss-cross rigging and multiple pedestals so long characteristic of tower construction. As a result, many modern elevated tanks have been constructed with a single vertical pedestal that is designed to provide all of the structural support for the tower. The construction thus must take into consideration, factors such as column buckling limits, soil bearing capacity, direct and torsional wind loadings, possible assembly methods and remote safety considerations.

Existing towers have handled many of these factors by designs which do not take full advantage of the inherently compact and attractive single pedestal approach. For example, virtually all existing single pedestal water towers are provided with a greatly enlarged conical base portion, which, in existing designs necessary to develop sutficient soil bearing area so as to resist tilting forces caused by direct winding loading. The enlarged base not only reduces the space saving advantages gained by the single pedestal approach, but also makes it impossible to assemble the tank at ground level and hoist it upwardly along the central pedestal to its final position. While proposals have been made as to this latter assembly method, no practical tower construction employing this method is in existence. Furthermore, in existing singlepedestal-type water tower constructions, the pedestal is subjected to complex forces which result in a generally oversized and hence less eflicient structural design.

Accordingly, it has been an object of my invention to fully investigate the theoretical and practical problems associated with single pedestal elevated towers, their assembly and their safe maintenance;

Another object of my invention has been to provide an elevated tower structure employing a single pedestal for its vertical support, which pedestal is subjected substantially entirely to compression stresses so as to minimize its overall size, weight and cost;

Another important object of my invention has been to provide an elevated tank supporting structure including an optimized guy line arrangement by which substantially all live loadings are absorbed within suitable tension members;

A further object of my invention has been to provide an elevated tank construction having a tank portion that can, as a practical matter, be nearly completely assembled at ground level and simply hoisted to a final position atop the tank supporting structure;

3,219,224 Patented Nov. 23, 1%65 These and other important objects of my invention will be apparent to those skilled in the art upon reading and understanding the following disclosure of my inventive concepts and a description of some specific illustrative embodiments thereof.

By a generalized and simplified stress analysis of any single pedestal type tower it is seen that the critical factor in the pedestal will often be compression buckling. I have determined that direct horizontal wind loadings can contribute significantly to the critical buckling stress. Unpredictable complex stresses caused by combined torsion, and bending often aggravated by harmonic effects must also be considered. I find most satisfactory method of handling the unpredictable effects of complex stresses is to eliminate or minimize the basic component parts of those stresses. Another critical stress consideration in the column design is the compression strength of the soil or ground bearing area developed by the pedestal base structure. The most variable constituent of this consideration is the transferred direct wind loadings which are effectively eliminated by my construction.

One concept or phase of my invention relates to the use of a pedestal base construction which permits relatively free universal pivotal movement of the pedestal about its lower end. Such freedom of movement virtually eliminates bending moments that would otherwise be induced within the pedestal body due to horizontally acting wind loadings. It will be recognized a bending moment within the pedestal will create an additional localized compressive force in the pedestal requiring an enlarged design to meet the total stress requirements. Furthermore bending forces, which in a conventional pedestal are transferred to the foundation thus locally increasing the soil bearing stress, are isolated from the foundation by the freedom of movement provided by my construction.

Another phase of my invention relates to the use of a guy construction which absorbs substantially all of the wind or live loadings as tension stresses whereby bending and torsional strain of the pedestal is greatly minimized and the pedestal can thus be reduced in dimension. Furthermore, by absorbing such live loadings in tension members, the problem of acquiring sufiicient soil bearing area is eliminated by the use of several underground land or ground anchors. The holding capabilities of a land or ground anchor can be increased by increasing its depth or vertical dimension whereas, a conventional foundation, or compressive soil engaging member depends upon horizontal bearing area for its strength. It will thus be appreciated by those skilled in the art that the surface area around the pedestal is more efficiently employed in my construction than in existing wide-based, guyless tower constructions.

I have determined that the most preferable guy configuration is one having six guy lines that attach substantially tangentially (about 5 in horizontal projection) to the upper end of the support pedestal in a symmetrical and completely circumscribing arrangement. A guy attached substantially tangentially will be subjected to a greater percentage elongation upon a given torsional displacement than a guy that intersects the pedestal circumference at a high angle. The efficiency of the guys is thus maximized, since the efiectiveness of the guys in absorbing the total torsional wind loadings depends upon maximizing the percentage of the torsional load accepted by the guys with respect to the percentage of the torsional load imposed upon the pedestal.

I have also found that six guy lines can be efficiently arranged by grouping the guys in pairs whereby the guys act individually and in consert to resist both direct and swirling winds. The guy arrangement also provides a sufficient safety factor against the breakage of one of the guys.

A further phase of my invention relates to the combination of a cylindrical pedestal (constant horizontal crosssection) with the previously mentioned eflicient stress handling structural components. In the absence of the novel structural components of my invention, a cylindrical pedestal is not practical. It is thus possible for the tank to be nearly completely assembled at ground level around the cylindrical pedestal and then hoisted upwardly therealong to its final elevated position.

A clearer and more complete understanding of my invention will be had from the following description of some illustrative embodiments of my invention, wherein specific reference is made to the accompanying drawings of which:

FIGURE 1 shows an elevated storage tank structure constructed in accordance with my invention;

FIGURE 2 is a top or plan view of the elevated tank structure shown in FIGURE 1;

FIGURE 3 is a diagrammatic view of a portion of the elevated tank of FIGURE 1 showing the effectiveness of my novel guy construction;

FIGURE 4 is an enlarged fragmental cross-sectional view of a preferred pedestal support construction employed in the elevated tank of FIGURE 1;

FIGURE 5 is a cross-sectional view of the pedestal support construction taken along lines V-V of FIGURE 4; and

FIGURE 6 is an enlarged fragmental cross-sectional view of a second or alternative preferred pedestal support construction employed in the elevated tank of FIGURE 1.

Referring now more specifically to the drawings, in FIGURE 1 there is shown a storage tower 10 including an elongated vertical mast, column or pedestal 11 that is substantially cylindrical throughout its length, and a storage reservoir or tank 12 which is securely mounted on the upper end of the pedestal 11. The pedestal 11 is suppored at its lower end by a foundation or base structure 20 that is preferably of the type shown in either FIGURES 4 and 5 or FIGURE 6. The pedestal 11 is also restrained at its upper end by a plurality of especially arranged flexible tension members or guys 13 that act to absorb and resist a major portion of the live or wind loadings on the tower. The guys 13 are secured at their lower ends to deep earth anchors 14.

Turning now to FIGURES 2 and 3, which show the angular arrangement of the guys 13, it will be seen that six guys 13 are employed and are arranged in adjacent pairs to form an equiangular three pointed star that completely circumscribes the pedestal 11. The enlarged diagrammatic view of FIGURE 5 illustrates the improved torsional response of the guys when arranged in accordance with my invention.

As shown in FIGURE 3, each guy 13 makes a slight angle A (in horizontal projection) with the pedestal 11, of about 5. In effect, the guys 13 are substantially tangent to the pedestal 11. By way of analysis it will be seen that for a given angular displacement B, the upper guy 13 as shown in FIGURE 3 will elongate an amount B. This elongation or strain in the guy 13 induces a corresponding large reaction or restraining force in the guy. Thus, of the total torsional force on the system, a minimum is distributed to the pedestral 11 and a maximum is absorbed by the guys 13. For comparison sake, a similar analysis can be applied to a hypothetical guy 13' that makes a large angle with respect to the pedestal 11. Under the same given angular displacement B, the hypothetical guy 13' will elongate only by the amount B. Accordingly, a significantly less reaction will be developed to resist torsional strain on the pedestal 11.

Returning to FIGURE 2, it will be observed that the critical position of the wind with regard to the elfectiveness of the guys 13 in resisting bending of the pedestal 11 or lateral displacement of the tank 12, occurs when the wind acts towards the intersection of two guys as indicated by the arrow W. In this wind condition, the resisting guys 13 individually contribute a minimum of load resistance due to their high angle with respect to the wind. However, a total of four guys are effective to resist the wind loading thus compensating for their minimum individual contribution. Furthermore, in the critical wind condition under consideration, breakage of one of the wind resisting guys 13 will leave three guys remaining to absorb the wind loading thus providing a substantial factor of safety.

A preferred embodiment of elements employed in the pedestal base structure 20 is shown in FIGURES 4 and 5. In FIGURE 4 the pedestal 11 is welded to a planar downwardly-facing annular upper bearing plate or surface forming portion 21 that is resiliently supported on an annular neoprene bearing pad 22 carried by a planar upwardly-facing annular lower bearing plate or surface forming portion 23. The lower plate 23 is held level on a grouting foundation layer 24 which is formed in place on the upper surface of a substantially rigid earth-imbedded foundation block or pier 25.

As shown more clearly in FIGURE 5, a plurality of pin means such as anchor bolts 26 carried by the lower plate member 23, extend upwardly therefrom and are arranged in an annular series. The bolts 26 extend somewhat loosely through the plate 21 where they receive appropriate nuts 27. During assembly of the tower 10, the nuts 27 are tightened on the bolts 26 to provide clamping means that hold the pedestal 11 rigidly in its vertical orientation. After assembly is completed, the nuts 27 are loosened and locked to permit the pedestal 11 to pivot about its base by compressing the neoprene-bearing pad 22. The pivotal freedom of movement thus relieves any bending moment that would otherwise be induced. The bolts 26 in their loosened condition permit the desired pivotal movement of the pedestal 11, but prevent significant lateral or sidewise displacement that could result in dislocation of the elements over a period of time. In this construction the upper bearing plate 21 may extend across the bottom of the pedestal as shown and contain suitable ducting so that the pedestal can be used for storage. In the alternative, the upper bearing plate 21 need be only as large as the lower hearing plate 22, leaving a large central opening for the service ducting.

An alternative preferred embodiment of the foundation or base structure 20 (referred to as 20') is shown in FIG- URE 6. In this embodiment, the pedestal 11 is provided with a welded concave-downwardly spherical part, downwardly-facing surface forming portion or socket 21 that is effectively supported by a complementary shaped convex-upwardly spherical part, upwardly-facing surface forming portion or ball 23. Preferably a neoprene bearing pad 22 is positioned between the spherical parts 21' and 23' to aid in permitting relative pivotal movement therebetween. The lower spherical part 23' is supported by a short tubular section 11' and flange 24 which rests on a concrete pier of foundation block 25' that is similar to that described in connection with FIGURE 4. A plurality of assembly bolts 26' engage suitable brackets on the pedestal 11 and the tubular section 24 to provide clamping means that rigidly hold the pedestal 11 in a rigid vertical orientation during assembly. After assembly, the bolts 26' are completely removed to permit free pivotal movement of the pedestal 11 with respect to the base 20'. The spherical shape of parts 21' and 23 prevents lateral displacement without the aid of bolts 26'.

The service ducting for the tower 10 passes through the spherical parts 21' and 23 as shown in FIGURE 6. The ducting includes a main service pipe 27' for carrying fluent material between the tank 12 and the outside, a flexible coupling 28' and a transition pipe 29' that is welded to the upper spherical part 21' of the pedestal 11. A small but suflicient clearance open portion is provided in the lower spherical part 23' to permit freedom of movement of the transition piece and the spherical part 21'.

From the foregoing it will be seen that live loadings upon and in the pedestal 11 are efiiciently absorbed by the guys 13 which are anchored securely into the earth. The holding capabilities of the earth anchors 114 can be readily increased simply by increasing their depth or vertical length. It will also be seen from the foregoing that due to the pivotal connection between the pedestal 11 and the base 20, the small lateral tank displacement which exists despite the guys 13 will not induce substantial bending moments in the pedestal 11. The stress distribution in this construction thus is such that the pedestal 11 can be constructed with a minimum diameter and with a uniform cross section along its vertical extent. It will further be seen that no significant direct wind loadings are transmitted to the base structure 20 or 20' and accordingly the base structure is not required to develop the large soilbearing area to resist such forces. The direct wind loadings are substantially entirely absorbed by the guys 13 and held by the guy earth anchors 14 which easily can develop whatever holding requirements there may be without covering a large surface or sub-surface horizontal area.

One of the most significant results of these various stress distribution features is the practical use of a cylindrical pedestal. The cylindrical pedestal 11 permits the tank 12 to be nearly completely assembled at ground level (in the position shown by broken lines in FIGURE 1) and then hoisted along the cylindrical pedestal 11 to its final elevated position. The expediency of such assembly method, as well as safety and cost factors, should be obvious to those skilled in the art. Existing single pedestal elevated towers employ a greatly widened almost conicalshaped base portion to develop resistance to bending loads and primarily to develop suflicient soil-bearing area to resist wind loadings. Of course, the enlarged base portion of the tower prevents ground level assembly.

Those skilled in the art after reading this disclosure will appreciate that I have devised a new elevated storage tower having several novel stress distribution features. It will also be appreciated that these features that contribute to an overall compact and attractive construction make possible an efficient and safe ground level assembly method heretofore sought after, but never practically attained.

While some preferred embodiments of my invention have been shown herein for purposes of illustration, it is understood that various changes may be made in these constructions by those skilled in the art without departing from the spirit and disclosed concepts of the invention as particularly pointed out and defined in the appended claims.

I claim:

1. An elevated storage tower construction comprising, a centrally-located ground-mounted support base, a vertically-elongated pedestal mounted at its lower end on said support base to project upwardly therefrom, a storage tank securely-mounted centrally of its bottom portion on an upper end of said pedestal to project radially-outwardly therefrom and provide an integral structure therewith, three earth anchors substantially equally-spaced with respect to each other about said integral structure and positioned radially-outwardly thereof in an equiangular spaced relationship thereabout, three pairs of flexible guys, the guys of each of said pairs being connected together at their lower ends to an associated one of said anchors, the guys of each of said pairs being secured at their upper ends in a circumferentially-spaced adjacent relation with each other to said integral structure adjacent the bottom portion of said tank and the upper end portion of said pedestal to provide a downwardly-radially-outwardly-in clined triangular guy system, one guy wire of each of said pairs being secured at the same position on said integral structure as an adjacent guy of an adjacent pair, whereby each guy wire at its upper end has a common point of connection to said integral structure with an adjacent guy wire of an adjacent pair, each guy of said pairs being positively-secured at its upper end to said integral structure to extend tangentially-outwardly therefrom and resist torsional moment on said integral structure, said support base having a pair of opposed upper and lower bearing faces, means connecting said opposed faces together and having portions to inhibit lateral movement and provide pivotal movement between said opposed faces, whereby said pedestal will have limited pivotal movement with respect to said lower bearing face as restrained by said flexible guys to thereby minimize bending movement on said pedestal, said upper and lower bearing faces being of complementary spherical shape, a transition pipe extending upwardly through said upper and lower bearing faces and being secured to one of said bearing faces and extending through an enlarged open portion in the other of said bearing faces, a service pipe extending upwardly through said support base for conducting fluent material, and a flexible coupling connecting a lower end of said transition pipe to an upper end of said service pipe.

2. A storage tower as defined in claim 1 wherein each guy of said pairs intersects said integral structure at an angle of about 5 in horizontal projection.

3. A storage tower as defined in claim 1 wherein a resilient pad is positioned between said upper and lower bearing faces.

References Cited by the Examiner UNITED STATES PATENTS =1,210,411 1/1917 Bryhan 248 22 1,785,251 12/1930 Etheridge 248350 1,802,107 4/1931 Camerota 248-22 1,947,515 2/ 1934 Blackburn 220-l 2,295,514 9/ 1942 Brinkman 22018 2,315,023 3/1943 Stevenson 22026 2,370,614 3/1945 Bohm 2201 2,427,676 9/1947 Horton 2201 2,683,550 7/1954 Mummert 220--1 2,690,273 9/ 1954 Arne 2201 2,792,231 5/ 1957 Compton 24822 3,040,479 6/ 1962 Ayotte 50.5 3 3,057,119 10/1962 Kessler 5053 3,073,018 1/1963 Gauthron 2201 3,109,551 11/1963 Bishop et a1 220-1 THERON E. CONDON, Primary Examiner.

Claims (1)

1. AN ELEVATED STORAGE TOWER CONSTRUCTION COMPRISING, A CENTRALLY-LOCATED GROUND-MOUNTED SUPPORT BASE, A VERTICALLY-ELONGATED PEDESTAL MOUNTED AT ITS LOWER END ON SAID SUPPORT BASE TO PROJECT UPWARDLY THEREFROM, A STORAGE TANK SECURELY-MOUNTED CENTRALLY OF ITS BOTTOM PORTION ON AN UPPER END OF SAID PEDESTAL TO PROJECT RADIALLY-OUTWARDLY THEREFROM AND PROVIDE AN INTEGRAL STRUCTURE THEREWITH, THREE EARTH ANCHORS SUBSTANTIALLY EQUALLY-SPACED WITH RESPECT TO EACH OTHER ABOUT SAID INTEGRAL STRUCTURE AND POSITIONED RADIALLY-OUTWARDLY THEREOF IN AN EQUIANGULAR SPACED RELATIONSHIP THEREABOUT, THREE PAIRS OF FLEXIBLE GUYS, THE GUYS OF EACH OF SAID PAIRS BEING CONNECTED TOGETHER AT THEIR LOWER ENDS TO AN ASSOCIATED ONE OF SAID ANCHORS, THE GUYS OF EACH OF SAID PAIRS BEING SECURED AT THEIR UPPER ENDS IN A CIRCUMFERENTIALLY-SPACED ADJACENT RELATION WITH EACH OTHER TO SAID INTEGRAL STRUCTURE ADJACENT THE BOTTOM PORTION OF SAID TANK AND THE UPPER END PORTION OF SAID PEDESTAL TO PROVIDE A DOWNWARDLY-RADIALLY-OUTWARDLY-IN CLINED TRIANGULAR GUY SYSTEM, ONE GUY WIRE OF EACH OF SAID PAIRS BEING SECURED AT THE SAME POSITION ON SAID INTEGRAL STRUCTURE AS AN ADJACENT GUY OF AN ADJACENT PAIR, WHEREBY EACH GUY WIRE AT ITS UPPER END HAS A COMMON POINT OF CONNECTION TO SAID INTEGRAL STRUCTURE WITH AN ADJACENT GUY WIRE OF AN ADJACENT PAIR, EACH GUY OF SAID PAIRS BEING POSITIVELY-SECURED AT ITS UPPER END TO SAID INTEGRAL STRUCTURE TO EXTEND TANGENTIALLY-OUTWARDLY THEREFROM AND RESIT TOR SIONAL MOMENT ON SAID INTEGRAL STRUCTURE, SAID SUPPORT BASE HAVING A PAIR OF OPPOSED UPPER AND LOWER BEARING FACES, MEANS CONNECTING SAID OPPOSED FACES TOGETHER AND HAVING PORTIONS TO INHIBIT LATERAL MOVEMENT AND PROVIDE PIVOTAL MOVEMENT BETWEEN SAID OPPOSED FACES, WHEREBY SAID PEDESTAL WILL HAVE LIMITED PIVOTAL MOVEMENT WITH RESPECT TO SAID LOWER BEARING FACE AS RESTRAINED BY SAID FLEXIBLE GUYS TO THEREBY MINIMIZE BENDING MOVEMENT ON SAID PEDESTAL, SAID UPPER AND LOWER BEARING FACES BEING OF COMPLEMENTARY SPHERICAL SHAPE, A TRANSITION PIPE EXTENDING UPWARDLY THROUGH SAID UPPER AND LOWER BEARING FACES AND BEING SECURED TO ONE OF SAID BEARING FACES AND EXTENDING THROUGH AN ENLARGED OPEN PORTION IN THE OTHER OF SAID BEARING FACES, A SERVICE PIPE EXTENDING UPWARDLY THROUGH SAID SUPPORT BASE FOR CONDUCTING FLUENT MATERIAL, AND A FLEXIBLE COUPLING CONNECTING A LOWER END OF SAID TRANSITION PIPE TO AN UPPER END OF SAID SERVICE PIPE.

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