Cable supported pool structure

A pool has a pool wall support structure incorporating an outer tensioned cable which is spaced outwardly from the pool wall and thrust bearing struts between the cable and the pool wall. A walkway deck or other load may be mounted over and supported by such struts. Adjustment of the tension in the cable may be monitored by reference to corner plates mounted on the pool walls and having slotted holes.

FIELD OF THE INVENTION 
This invention relates to an improved structural support system for 
retaining and supporting the walls of above ground pools and pool-side 
decks and steps. 
BACKGROUND OF THE INVENTION 
In the design of pool wall structures, several problems in particular are 
encountered. These all arise from the fact that in endeavouring to contain 
a large mass of water, a substantial hydraulic pressure is developed and 
applied against the surrounding wall. This pressure creates a spreading 
force which tends to stretch the pool wall and requires a pool wall 
support structure that provides a counteracting force to contain the water 
in the pool. Where the wall is composed of segmented portions, the force 
of the water tends to separate the pool wall segments from each other at 
their corners and cause corner spreading. Where the pool wall is not 
circular this pressure also differentially acts on pool wall segments with 
the tendency to reshape the walls into a circle. In cases where the pool 
wall segments are formed of flat panels supported at their ends by being 
joined to the corner of the next adjacent panel, the hydraulic pressure 
tends to cause bulging in the centre of the panel. 
An additional problem encountered in constructing above ground pools having 
a pool-side walkway, deck or steps, is the expense and complication of 
supporting these structures. 
PRIOR ART TO THE INVENTION 
Techniques applied in the past to support the walls of non-circular above 
ground pools against bulging, and/or corner spreading and to support 
poolside decks and walkways have included: 
(1) use of anchoring buttresses which are set in pads or footings capable 
of resisting the outward force transmitted to them through the buttresses 
and capable of supporting pool-side decks and walkways by posts placed 
thereon; 
(2) attaching transverse tension bearing straps running underneath the pool 
liner and crossing from one side of the pool to the other side so as to 
counter-balance the corresponding forces developed on each side; 
(3) use of horizontally deployed trusses, beams or girders attached to the 
pool walls to stiffen them against sideways deflection or bulging and 
sometimes to carry pool-side decks and walkways; 
(4) use of heavy, ridged corner connecting structures to maintain angular 
relationships and transmit tension within the pool wall between adjacent 
wall segments. 
Metal hoops and encircling cables have been used to resist the spreading 
and stretching of pool walls in configurations wherein the pool is of 
circular shape. This arrangement is equivalent to the hooped barrel in 
which a circular array of staves is confined by a circular hoop fitted 
around the sides of the barrel. Such hoops and cables have, however, 
generally been located directly adjacent to the circular pool wall that 
they contain. No case is known of a pool wall support structure which 
takes full advantage of a totally encircling cable which is stood-off from 
the pool walls by thrust-bearing struts. Nor has a cable been used to 
support pool-side decks and walkways or to provide support for walk-in 
steps which form a segment of the pool wall. 
All of the above listed systems involve deficiencies. The installation of 
footings can be expensive. In winter conditions, frost may heave these 
footings, causing twisting between the structure associated with the 
walkway, deck or steps, and the pool wall to which they are attached. The 
use of under-pool straps limits the extent to which the pool may be 
deepened by excavating between the pool walls. Extensive use of girders, 
beams and trusses can increase cost, as can the use of heavy ridged corner 
connecting structures. 
Where riged corner couplings are used to connect pool wall panel segments 
in the vicinity of the panel ends, stress must be transmitted from the 
coupling to the panels. As a consequence, the ends of panels so connected 
must be sufficiently reinforced to absorb this stress. This may, in turn, 
result in pool corner junctions which are particularly riged and unable to 
shift and flex in response to forces developed by sloshing of water in the 
pool or by heaving of the ground due to frost in the winter. 
In cases where a deck or walkway hangs outwardly from a pool wall over 
diagonal struts which extend to the base of the pool wall, a considerable 
tension is applied to the upper rail which may cause deformation of the 
pool wall or require excessively heavy reinforcement to carry the load. 
It has been proposed in the U.S. Pat. No. 3,564,623 issued to J. I. 
Shaeffer in 1971 to form a pool wall support structure using an outer 
frame assembled from a series of triangularly braced trusses. Each truss 
as described incorporates struts which extend outwardly from the plane of 
the inner wall of the frame segment associated with the truss. The struts 
are disposed along the truss in a series of "X" configurations and are 
coupled to a tensioned cable at the juncture of each "X" that is formed. 
This construction produces a trussed frame segment that may then be 
assembled by joining a series of such segments at their ends by means of 
angle iron to form the frame for containing the pool wall. The tensioned 
cable within each individual truss assembly is held at its two ends by 
sleeves tightened by nuts with washers. Further, the cable in each truss 
assembly is held in a straight line running for virtually the entire 
length of the truss. The cable does not encircle the pool. 
According to this prior patent, within the frame, a crib-type inner 
framework may be provided to transfer hydraulic pressure from any desired 
shape of pool to the outer truss wall frame. No distinction is made as to 
the orientation of pools of non-circular shape with respect to the outer 
frame and the cable segments contained therein. Nor is any distinction 
made as to which sides of a non-circular pool should preferentially face 
the center or ends of each truss assembly. No provision is made for 
supporting a load above the cable or the "X" brace struts. 
SUMMARY OF THE INVENTION 
Accordingly, it is one of the objects of this invention to effect a pool 
wall support structure in which; 
(1) the spreading force of water is constrained; 
(2) the tendency of flat pool wall segments to bulge is resisted; 
(3) the angular relationship of adjacent wall segments in a non-circular 
pool configuration is maintained; 
(4) support is provided for a walkway, steps or decking, mounted along the 
outside border of a pool wall; and, 
(5) means is provided to serve as an indicator of the proper adjustment of 
the pool support structure. 
According to this invention, in its broadest scope, a freestanding pool 
wall support structure is provided with a tensioned cable which is fixed 
in association with at least a portion of the pool wall and which is 
stood-off from the pool wall portion by thrust-bearing struts. In every 
instance where the cable is connected to a thrust-bearing strut, the cable 
changes direction. 
By a further feature of the invention, in the case of pool walls which are 
circular or of the shape of a regular polygon, the cable is disposed in a 
virtually circular shape in the form of a polygon (of not necessarily the 
same number of sides as the pool). 
In a further feature of the invention, in the case of non-circular pool 
having only positive curvature, the cable is displaced further from pool 
wall sections having a lesser degree of curvature, than from wall sections 
of greater curvature. In the case of a pool of oval shape, or generally 
oval polygonal shape, the cable is placed to form a more nearly circular 
configuration than the pool it surrounds. 
By a further feature of this invention, a portion of the associated 
tensioned cable is stood-off from the pool walls by a pair of angled upper 
and lower thrust-bearing struts. The lower strut terminates at the base of 
the pool wall and is angled upwardly proceeding away from the pool wall 
and towards the junction with the other strut. The upper strut extends 
upwardly back towards the pool wall from this junction, contacting the 
pool wall above the base of the pool wall. The tensioned cable is coupled 
to the struts, or extensions thereof, at a point outwardly displaced from 
the pool wall. 
By a further feature of the invention a pool-side deck, walkway, or step 
assembly is mounted outwardly from the pool wall and is supported on the 
combined strut and cable formation. 
By a further feature of this invention, a pool, which is either circular or 
non-circular, is surrounded by a structure which confines the water within 
the pool. Coupled to a section of this structure, or attached to an 
independent encircling cable, is a further tensioned cable segment which 
is stood-off from the pool wall by at least two pairs of struts of the 
form described above. A deck, walkway or step assembly is then mounted 
between the two pairs of struts, supported thereon with one end thereof 
terminating at the pool wall and the other end extending outwardly 
therefrom and supported on the strut and cable formation.

In FIG. 1, an eight-sided pool wall is depicted having end walls (10) and 
corner walls (11) constructed of standard size 4 foot by 4 foot plywood or 
press board panels. Although plywood walls are shown throughout, these 
panels may also be made of sheet steel or of reinforced fiberglass plastic 
construction. Side walls (12) are constructed of similar materials in 4 
foot by 8 foot panels. These plywood panels are horizontally stiffened 
along their upper and lower edges with 2.times.4 inch wood framing (13) or 
by steel "U" channels of equivalent dimensions which serve as rails. The 
panels also have for support a series of vertical braces (14) of similar 
materials to the rails located at the ends of each panel and on two foot 
centres there between. 
From the lower edge or base and from a point directly thereabove on each 
panel at their respective ends, as shown in FIG. 2, extend two struts (15) 
and (16) in pairs meeting to form a "V". These struts may be of either 
2.times.4 inch wood or steel "U" channels. Additional struts are similarly 
mounted at the central vertical braces on the 4 foot by 8 foot panels. 
Surrounding the pool and coupled to the struts is the tensioned cable (17) 
shown in FIG. 1. Tension is developed in the cable by means of the 
turnbuckle (41). The cable appropriate for this size of pool when filled 
to a depth of 48 inches is of 1/2 inch or 5/8 inch diameter twisted steel 
wire, depending on the strength of the wire. Although referred to as a 
"cable" throughout this disclosure it is contemplated that this expression 
comprises any suitable tensioning element whether in the form of a rope, 
strap, chain or rod. 
The cable runs in straight lengths between each consecutive pair of struts, 
changing direction as it passes by the ends of the struts. This change or 
deviation in the direction of the cable gives it the shape of a polygon. 
The connecting points between the cable and struts surrounding the 
generally oblate pool wall are further displaced from the pool wall 
opposite the longer side walls (14) which are less curved than the walls 
in the end and corner wall region. The result is that the polygon formed 
by the cable is more nearly circular than the pool walls it surrounds. 
"Curvature", in the case of a pool wall formed from a series of straight or 
flat pool wall segments, is intended to refer to the curvature of a smooth 
curve that could be constructed so as to pass through the consecutive 
corner points of the pool wall segments where they are joined. "Positive 
curvature" is intended to mean a curve which appears as concave when 
viewed from within the region contained by the pool walls. 
In the case of pool wall portions that have negative curvature, that is, 
walls that deflect inwardly (as found, for example, on a kidney-shaped 
pool) and are convex when viewed from within the pool wall such pool wall 
portions, in the absence of an external support structure, will be in a 
state of compression. The force developed within such wall portions will 
then be transmitted to adjacent wall portions which may, in turn, require 
additional support to absorb this force. Under these circumstances, it may 
be appropriate to displace the encircling cable further from such adjacent 
wall portions than from other wall portions having a lesser degree of 
curvature to a greater degree than would be appropriate if the pool wall 
portions were of continuous positive curvature. 
In FIG. 2, a pool wall cross section is shown mounted on the ground (18) 
with water (19) in the pool. A liner lies against the inner face of the 
pool wall (20) and extends downward and across the pool bottom to the 
other side. The plywood panel side wall (12) is shown with a vertical 
brace (21) fastened thereto with screws (not shown). Horizontal rails or 
braces (13) are similarly attached at the base and along the upper edge of 
each of the plywood panel sidewalls (12), end walls (10) and corner walls 
(11). 
The lower strut (15) is shown attached to and extending from the bottom of 
the vertical brace to which it is fastened by a bolt (23). The upper strut 
(16) is attached to the vertical brace by a bolt (24) and extends 
outwardly to where its other end is attached to the remaining end of the 
lower strut (15) by a bolt (25). 
On the upper strut (16) is fastened a "U" bolt (26), bolted to the upper 
face of the strut. The encircling cable (17) passes through the space 
formed within this "U" bolt and transmits force to the struts (15,16) by 
pressing against the upper side of the strut (16). 
The struts extending between the cable and the pool walls will be exposed 
to a sideways force if not mounted perpendicularly to the pool wall. A 
sideways force will also be created if the struts are not aligned in the 
plane bisecting the interior angle formed by the cable as it changes 
direction in passing by the strut. For security, therefore, all struts so 
exposed may be clamped both to the pool wall panels and to the cable in 
such a way as to prevent sideways twisting. 
A vertical walkway and railing support (27) extends upwardly from the apex 
of the two struts (15,16) optionally joined thereto by the same bolt (25) 
or by other fastening means. This joining may also be effected elsewhere 
on the struts (15,16) other than at their apex. Alternately the struts may 
be joined separately to the vertical support, in either case, the cable 
may be attached to the vertical support as an alternative to being 
attached to one of the struts. Deck supports (28) in the form of joists 
extend horizontally, attached at one end by a bolt (29) to the vertical 
support (27) and at the other end to the vertical brace (21) by a bolt 
(30). 
In FIG. 3 an alternate form of structure is shown for supporting a walkway 
or other load. In this version the floor joist (28) is replaced or 
supplemented by a diagonally mounted strut (30) running from the vertical 
support (27) at the bolt (29) to the base of the pool wall at bolt (23). 
This strut crosses the upper "V" strut (16) and may optionally be joined 
at its intersection with a bolt (31) to reduce its unsupported length. 
Deck supports (28a) may then be fastened between consecutive vertical 
supports (27) and along the pool wall panel braces (21) providing support 
for decking (32). If sufficiently riged struts, braces and couplings are 
used, the lower strut (15) may be dispensed within this configuration. 
In FIG. 4 an alternative shape of pool is shown in which the corner walls 
(11a) are 8 feet long and the side walls (14a) are 4 feet long. The 
centers of the longer corner wall panels (11a), which are more susceptible 
to bulging, are supported by centrally placed struts (15a and 16a). Again 
the cable (17) is shown as encircling the pool, displaced further from the 
pool walls in those regions opposite the side panels (14a) where the pool 
wall has effectively less curvature than in the vicinity of the end panels 
(10a). This renders the cable more nearly circular than the pool wall 
which it surrounds. Again, curvature is used here in the sense as defined 
earlier, above, where the pool wall is formed from a series of straight 
panel segments. 
At the more sharply curved end, the cable (17) runs adjacent to the pool 
wall lying against the vertical braces (21) at approximately the same 
height as the cable (17) is connected to the struts (15,16) elsewhere. A 
sliding contact may be obtained by placing a sleeve formed from a split 
section of plastic pipe around the vertical brace (21) and between it and 
the cable (17). The cable (17) may also be contained by "U" bolts or other 
means (not shown) to attach it to the vertical braces (21). 
It is desirable that the cable be coupled to a strut, strut extensions or 
vertical supports at a location mounted at a higher elevation than the 
base of the pool wall. Where the wall alone is being supported by the 
cable and struts, the optimal height for the cable is one third the depth 
of water in the pool above the pool wall base. If the cable is either 
higher of lower than this optimal height, a net torque will be developed 
that must be absorbed by other elements of the pool wall support 
structure. For minor deviations from this optimal height the required 
counteracting forces can conveniently be developed by the ground or by the 
pool wall itself and by the corner coupling elements joining adjacent pool 
wall sections. 
When the same cable is being used both to contain the pool walls and to 
support a free standing pool-side deck, walkway or steps, it is preferable 
that the cable be located above the optimal height referred to above. The 
weight of the deck structure above, together with any load being applied 
thereto, can then serve to absorb and reduce part of the net torque being 
developed by the cable and struts. This is preferable to having such loads 
enhance the net torque that exists, a condition that will occur if the 
cable is mounted below its optimal height. 
The suspended, freestanding support structure described herein for 
supporting walls and a pool-side deck, walkway or steps may be applied to 
either a circular or non-circular pool. In either case, if the object is 
solely to support a deck or other load struts need pass between the cable 
and the pool walls only in the regions where a vertical load is to be 
applied to the combined cable-strut structure. Alternately, a cable 
dedicated to providing a free standing support structure only for the 
walls may be run adjacent to the pool wall for a portion of the course of 
encircling the pool where the curvature is greater; and only be stood off 
from the pool wall by struts where the wall has lesser curvature. The 
cable in such cases need not encircle the pool, but may be attached to the 
pool wall so as to substitute a portion of the pool wall as a tension 
carrying structure in lieu of a portion of the cable. 
In FIGS. 5 and 6 an arrangement is shown by which a premoulded riged step 
assembly (33) is mounted in place of a panel section in a pool wall. Steps 
of this type can be obtained from Fox Pool Corporation of York, 
Pennsylvania. Where such steps are installed in place of a side wall panel 
in a pool wall portion of shallow curvature, such as the side wall (14a) 
shown in FIG. 4, they may be supported in a manner similar to that 
described for the walkway elsewhere herein. Where it is desired to install 
steps in the place of an end wall in a region of greater curvature, such 
as the end wall (10) in FIG. 1, or to install a walkway or deck adjacent 
to such an end wall, then the following structure may be constructed. 
In FIG. 5 the steps (33) are mounted on a lower rail (34) that meets with 
and is preferably joined to the lower rail elements of adjacent pool wall 
segments. A pair of vertical braces (35) may optionally extend upwardly 
from this rail (34) at the respective ends of the lower step to provide 
additional support for the lower step (36) of the step assembly (33). A 
further horizontal brace or rail (34a) may then extend between the upper 
ends of the vertical braces (35) to absorb partially any crushing force 
that may be imposed through the pool walls on the steps by the tension in 
the cable (17). 
Extending diagonally upwards from the lower rail (34) on either side of the 
steps are struts (37) which intersect with and are bolted to struts (38) 
which extend downwardly from the upper rail of the adjacent pool wall 
panels to which they are attached. The step assembly is then supported on 
these two pairs of struts of "V" shaped formation (37,38) by a transverse 
bar (39) passing between and mounted on the two sets of struts. 
The cable (17) which encircles the pool passes under the lower step (36) 
adjacent to the vertical braces (35). Since it is tensioned, it provides 
an inward force which counter balances, at least in part, the hydrostatic 
pressure developed by water (19) on the other side of the risers (40) 
which meet the lower step (36). 
This cable (17) is shown in plan view in FIG. 6 as it passes under the step 
assembly (33) and then on to a turn buckle (41) which is fastened in turn 
to the other end of the cable (17). The cable (17) coming from the step 
assembly (33) passes through an eye on the turn buckle and is then, as a 
returning cable portion (17a), looped back around the two pairs of struts 
of "V" formation (37,38) and then returned to the cable (17) to which it 
is clamped by a clamp (42). 
This returning cable portion (17a) is shown in FIG. 5 as pressing against 
the strut pairs (37,38) at the place where they cross. It may alternately 
be clamped by a "U" bolt or other means along the top or bottom sides of 
either of the struts (37,38) at a sufficient height above the ground to 
provide support for the step assembly (31) when loaded by a person 
descending thereon into the pool. 
The effect of using a single cable (17) which is looped back through a turn 
buckle eyelet to support the step assembly is to provide a tension in the 
returning cable portion (17a) equal to the tension in the main cable (17). 
An alternate arrangement permitting an independent adjustment of tension 
in the cable (17a) supporting the step assembly (39) would be to provide 
the supporting cable with an independent turn buckle and fasten both of 
its ends to the main cable (17) by clamps. A further variation would be to 
use an entirely independent cable which encircles the pool either 
adjacently to the pool walls or mounted on the pool wall support struts 
(15,16). Yet a further variation would be to fasten the ends of the step 
supporting cable (17a) to the pool walls so that the walls themselves 
carry the tension that must be absorbed. This may be done in conjunction 
with dispensing with the main cable (17) and relying on the attachment of 
the sides of the step assembly (33) to the adjacent pool wall segments for 
support. 
In FIGS. 7 and 8 details are provided of two corner connector elements that 
are adapted for use with an encircling cable support structure. The first 
element is a plate or sheet metal strip (43) bent into a "V" cross-section 
and fastened by bolts (not shown) to the upright braces (21) at the ends 
of adjacent panels. This is shown in plan view in FIG. 7. The point of the 
"V" is aligned with the inside seam of the pool wall at the corner (44) 
formed by the panels. To protect the vinyl liner that will be placed 
against the pool wall from being pinched in the seam a protective strip of 
metal or plastic (45) may be fastened along the corner of the sheet metal 
to screen it from the pool interior. 
An alternate equivalent construction is to incorporate the protective strip 
in two parts as flanges to pieces of sheet metal bent around and bolted to 
the respective end panel braces and of adjacent wall segments and 
enclosing the end of the sheeting which forms the pool wall. The two 
symmetrical sheet metal pieces may then be jointed by welding along the 
bend of the inside flanges to create the seam between the wall sections. 
The second element suitable for use as a corner connector for a cable 
supported pool is an angular corner plate adapted to be fastened to the 
upper rail or brace running along the top of each wall panel, and also to 
the lower rail or brace fastened along the bottom of each panel and 
forming the base of the pool wall. This element is shown in FIG. 8. 
Mounted at the ends of upper and lower rails (48) of adjoining wall panels 
is an angled corner plate (46) having slotted holes (47) which serve to 
indicate the state of stress, i.e. tension or compression, existing at the 
corners. Only the top plate is shown in FIG. 8. The plates (46) have two 
legs which are shaped and angled to fit respectively onto and lie adjacent 
to the surfaces of the ends of adjoining rails (48). Bolts (49) pass 
through holes (50) in the ends of each of the rails (48) which are aligned 
and pass through the slots (47) in the angled plates (46) when assembled. 
While two sets of slots (47) are shown, it is sufficient to have slots 
only in one of the arms of each plate. The bolts (49) are tightened to 
permit them to slide within the slots (47). 
When a corner is under compression, the bolts (49) tend to slide towards 
each other in the slots (47). Under tension, the bolts (49) tend to slide 
apart, towards the opposite ends of their respective slots (47). As long 
as a bolt is positioned relatively towards the centre of its slot (47) and 
away from the limit of travel at the ends of its slot (47) this is an 
indication that the corner is in a relatively modest or near zero state of 
tension or compression. 
When the pool wall structure is assembled initially the cable is lightly 
tensioned until all angled corner plates indicate that the corners have 
just entered a state of compression. As the pool is progressively filled 
with water, the tension in the cable is increased by adjusting the turn 
buckle whenever all of the angled corner plates indicate that the corners 
have entered a state of tension. Once the pool is filled to its desired 
level, the cable tension is adjusted so that all corners are in a near 
zero state of stress. Alternately, cable tension is adjusted so that some 
of the angled corner plates indicate that the associated corners are under 
compression; while other corner plates indicate a condition of tension. 
As an alternative to having a slot in the corner plate (46) slots may be 
formed in the rail (48) in lieu of one of the holes (50) in the rail (48). 
The tension indicating effect may be observed as the bolt (49), passing 
through holes in the corner plate, slides within the slot in the rail.