BACKGROUND Field of the Invention The present invention relates to building construction. The present invention relates to membrane structures. The present invention relates to attaching flexible, thin film, fabric, foil or laminate membranes to tubular structures. The present invention relates to enclosing geodesic domes and space frames and modifying that environment.
Description of the Related Art Geodesic Domes, U.S. Pat. No. 2,682,235 and Space Frames, U.S. Pat. No. 2,986,241, offer distinct advantages in structural and construction efficiency over conventional construction methods. Frameworks for these structures can be simply and readily fabricated from tubes, pipes or rods that are flattened on the ends and drilled, then bolted together. This has been a common method for hobbyist, do-it-yourselfers and professionals to build Geodesic Domes since the 1970's. To convert this type of structure to usable interior space, some type of cladding, sheeting, film or fabric cover is applied to the framework. Commonly, a one piece balloon shaped membrane is either draped over or suspended from inside of the structure. This requires relatively complex development geometries, fabrication methods and a large area for layout.
SUMMARY This method of attaching a membrane to a tubular framework enables the effective enclosure of such frameworks and is conceivably applicable to most any stable tubular structure, generally independent of its overall geometry or hub design.
Tubular geodesic domes and space frames, using this method of membrane attachment along with a simple bolt-together framework, provide a shelter of high efficiency at minimal cost. They are easily fabricated from common materials and assembled with simple tools. A single person can erect a relatively large structure over the course of several days. This method approaches the level of structural performance discussed in R. Buckminster Fuller's Building Construction U.S. Pat. No. 2,682,235.
This technique of attaching flexible thin films, fabrics and/or laminates to tubular frameworks, retains the membrane on the structure, while keeping the material taut over a wide range of operating temperatures. Keeping the membrane taut or tensed is important because a tight membrane does not fatigue to failure as readily as a loosely flapping membrane and thus lasts longer. A tight membrane is also quieter in gusty winds and reduces aerodynamic drag on the structure. This method of membrane attachment provides generally uniform tension throughout the membrane over all of the structure.
This method seals the panel edges and hubs, keeping wind, precipitation, debris, etc. out, providing an effective weather seal. It can also retain interior contents, for instance, humidity in a greenhouse or toxic gases in a hazmat containment application.
This method of membrane attachment permits the use of a wide variety of membrane materials for a wide variety of purposes, including, but not limited to, fabrics (natural or manmade materials), polymer films (clear, translucent or opaque, multicolored, printed and/or polarized), metal foils and laminates. These laminates could possibly include materials with electronically tunable opacity and reflectance (e.g. LCD) and thin film electronic video display and lighting (for information, entertainment, control, virtual reality, electronic camouflage, etc., e.g. LED), thin film audio (speaker) panels and photovoltaic (solar collector) panels, when the associated technologies are available. A wide variety of different membrane materials can be used on the same structure at the same time in different locations at the user's discretion. The user can also easily make and install custom panels and/or replacement panels from available materials. This can be especially useful in emergency situations and third world countries.
This system allows projections from the parent structure to have the same continuously tensed surface. Such projections can include walk-thru entries, vents, cupolas, balconies and towers.
Membrane panels can be maintained or replaced at any time, from the inside of the structure using ladders, scaffolding or platforms, without having to climb on the outside of the structure. Failure of any one of the panels, by itself, does not directly affect the integrity of the remaining panels. This method also allows for re-tensioning of panels on the fly with a built-in tension adjustment.
The manufacturing involved in this method requires minimal equipment, machinery and space. In the preferred embodiment, the structure's own struts can be used as the templates for the membrane panels. This makes for a simple, integrated construction system ensuring a good and reliable panel-to-structure fit.
DEFINITION OF TERMS
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- Membrane—Thin film, fabric or laminate attached to a structure in order to clad, shade or otherwise enclose it.
- Membrane Panel—A single membrane element. It is basically triangular shaped with truncated points, in the preferred embodiment.
- Membrane Structure—A structure that uses a membrane to shade or enclose it.
- Hub Cap—a circular membrane element attached at the hub to close that panel gaps at the hubs.
- Glazing—The act of attaching membrane panels to a structure.
- Abutting Edge—location where two membrane panels come together
- Re-tension—To reinstall clips along panel edges to increase the tension in the panel.
- Tubular—Having a circular cross section; being a linear right circular cylinder.
- Tubular Framework or Structure—Structure made from and comprised primarily of tubular elements.
- Strut—A single structural element of a tubular structure.
- Tongue—flattened end of a strut that is drilled and used to connect to other struts.
- Hub—Vertex or intersection of struts in a tubular structure. In the preferred embodiment, the struts are held together with a bolt or threaded rod, washers and nuts.
- Facet—Triangle or other shape on or within a structure defined by mutually interconnected struts. A face of a polyhedron.
- Strut Pattern—Arrangement of Struts around a Facet, herein designated as starting with the shortest going clockwise.
- Bare Struts—Struts that do not have membranes attached.
- Geodesic—Shortest distance between two points in space or on the surface of a sphere.
- Single Layer Geodesic Dome—A Geodesic Dome having most of its parts at the same radius from center, in other words, having no significant structural depth, as related to the center of the structure.
- The Dome Base—the intersection of the dome with the ground, slab, etc on which it sits.
- Dome Center Point—Center of the dome base.
- Dome Zenith—Very top or highest part of a dome. Often it is the hub at the center of a pentagon, but not necessarily.
- Dome Layers—Starting at dome zenith, layers are the concentric ring of triangles that are the same average distance from Zenith. They are installed at about the same time. The dome is raised by the addition of layers.
- Parent Structure—Larger structure like a Geodesic Dome or Space Frame to which a smaller structure, like a door or vent, is applied.
- Operating Temperature—The range of temperature in which a structure or part operates; being the range of temperature to which a structure is exposed over the normal course of a year, taking into account outside and inside air temperatures, direct solar heating, rain, wind, freezing precipitation, etc.
- Shading—Membrane or tarp material with the purpose of providing shade from or reflectance of the solar radiation.
- Inside View—View from Inside of the Structure
- Outside View—View from Outside of the Structure
- Integrated Construction System—A building system using a small set of standardized parts and with the structure itself being the templates for the enclosing panels.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a Geodesic Dome and FIG. 2 is a perspective view of a Space Frame Structure. These Figures are included as examples of the primary structures to which this method applies.
FIG. 3 is an oblique drawing of a Tubular Strut. This drawing is included to illustrate the type of strut used in the preferred form.
FIG. 4 is a perspective view of a Tubular Strut Hub. This drawing is meant as an example of a strut connection or hub. In a single layer geodesic dome, there are 4, 5 or 6 struts impinging on one hub, while in a space frame structure the number can vary from 3 to 9.
FIG. 5 is a section view of a Low Profile Hub. This hub allows for relatively smooth dome exterior to facilitate placing tarps and other shading on the outside of a structure. This is one of two different hubs used in conjunction with this method, in the preferred embodiment.
FIG. 6 is a plan view of the setup for making panels. This view is meant to show how a template is overlaid on a sheet of raw material. A scribe is then used to trace the panel outline and other markings are applied. The finished panel is cut out along the outer lines.
FIG. 7 is the front view of a Template for marking panels. This drawing shows three struts bolted together to create a panel template.
FIG. 8 is the front view of the scribe used for marking panels and shows how it sits on the template strut.
FIG. 9 is a section through the Scribe showing how it sits on the Template against membrane material and is used to mark the Membrane Material.
FIG. 10 is a plan view of a finished Membrane Panel. This drawing is to illustrate the general shape, markings and other aspects of a Membrane Panel.
FIG. 11 is a perspective diagrammatic view of a Geodesic Dome frame under construction with two layers of struts assembled. It is included to illustrate layering and the general location of the first panel to be installed.
FIG. 12 is a section view of a dome with a Zenith Anchor. This drawing is to illustrate how the Zenith Anchor locks in the location of the dome on the ground with only one anchor point.
FIG. 13 in an elevation view detailing the parts of the Zenith Anchor in the preferred form.
FIG. 14 is a diagrammatic cross section of a dome larger than ½ Sphere. This drawing is to illustrate what is meant by “a dome greater than ½ sphere” and how it can be effectively stabilized and anchored.
FIG. 15 is an inside view showing Step 1 of attaching the first panel: the membrane panel is overlaid on top of a facet of a structure in the proper orientation.
FIG. 16 is an oblique drawing of a Panel Clip. This drawing is included to illustrate a Panel Clip, in the preferred form.
FIG. 17 inside plan view showing Step 2 of attaching the first panel.
FIG. 18 is a section view showing how the membrane panel is initially clipped to the strut. The section line is shown in FIG. 17.
FIG. 19 is an inside plan view showing Step 3 of attaching the first panel.
FIG. 20 shows Step 4: smoothing the panel edge along the struts, applying tension, then adding end clips to the other 2 sides.
FIG. 21 clips are added in the middle of the strut, then remove any warps in the panel surface by re-tensioning the outer clips. This is the last step of attaching the first panel.
FIG. 22 is the outside view of the top of the first panel attached to the structure. This view is to illustrate the location of adjacent facets.
FIG. 23 is the inside view of the first panel with an abutting panel initially attached to the structure. This view illustrates how the abutting panel is attached to the structure prior to the abutting edge being clipped.
FIG. 24 section view showing how the abutting panels initially lays under the first panel. The section line is shown in FIG. 23.
FIG. 25 a section showing the panel clip placed against the panels and strut in proper alignment to start attaching the abutting panel.
FIG. 26 a section showing a panel clip in the proper position relative to the strut in order to secure the panels and to keep them taut. The section line is shown in FIG. 27.
FIG. 27 is an inside view of first panel and the abutting panel with three panel clips installed along the common strut.
FIG. 28 is an oblique exploded view of a tension bar on a strut section. The purpose of this Fig. is to show the parts of the tension bar and their arrangement. This view also shows the proper position of the bar relative to the strut in order to apply tension to the membrane panels and hold them in place.
FIG. 28A shows the complete tension bar assembly.
FIG. 29 is the inside view of the abutting edge showing the installation of outer tension bars.
FIG. 30 inside view shows the finished installation of tension elements along the common strut.
FIG. 31 is a section view through a strut and panel clip, illustrating the forces applied to the membrane panels by a panel clip.
FIG. 32 is a section view illustrating wrapping abutting panels with upward pointing panel flaps.
FIG. 33 is a section view illustrating wrapping abutting panels with downward pointing panel flaps.
FIG. 34 is a section view illustrating wrapping and securing panels along the base of a structure.
FIG. 35 is an inside view of a hub with a hub cap installed.
FIG. 35A is an inside view of a hub with a hub cap installed on a vertical strut.
FIG. 36 is a section view of a hub with a hub cap installed to illustrate how water is diverted over panel gaps at the hub. The section line is shown in FIG. 35.
FIG. 37 is an oblique view of the finished installation of two tension bars.
FIG. 38 is a perspective view illustrating a dome entryway and a vent. These are typical of type of projections that can easily be developed and enclosed with this method.
FIG. 39 is a perspective view of a TetraVent shown in open position.
FIG. 40 is a top view of a TetraVent tetrahedron nested into a structure.
FIG. 41 is a side view of the same TetraVent. View direction is shown in FIG. 40.
FIG. 41A is a detailed partial section of the TetraVent's hinge connection.
FIG. 42 is a section view through the hinge of a TetraVent showing how the vent membrane panel is attached to the parent structure and tensed. The section line is shown in FIG. 39.
FIG. 43 is a section thru mating edges of the TetraVent and the parent structure in closed position.
FIG. 44 is a diagrammatic section view through a dome with two TetraVents. One vent is open by way of an actuator line to ground level and one closed and locked by line to a zenith anchor. The section line is shown in FIG. 45.
FIG. 45 is a plan view of the dome in FIG. 44. This view is to illustrate how a shades or tarps may be securely overlaid on the outside of a dome of this type.
FIG. 46 is an elevation of a dome with a shade attached, being anchored to the base and tied off to Hitching Post Hubs.
FIG. 47 is an elevation of a Base Tie for a shade, detailing parts involved.
FIG. 47A is a partial section through a vertex foot used to elevate the base of the dome as shown in FIG. 46.
FIG. 48 is a section through a Hitching Post Hub showing the external protrusion for anchoring shades and for use as an equipment mount (e.g. camera, antenna, lights) and an internal eye bolt for hanging items from the structure interior.
FIG. 48A is a section showing a Dome Zenith Cap installed as part of the Hitching Post Hub for use at Dome Zenith to shed precipitation and seal the top.
FIG. 49 is a plan view of a structural facet with framing for a rectangular opening.
FIG. 50 is a section view of a typical non-triangular connection. The section line is shown in FIG. 49.
FIG. 51 is a plan view of the typical non-triangular connection detailed in FIG. 50.
FIG. 52 is a perspective of a geodesic dome showing ceilings, screens and walls suspended from the low profile and hitching post hubs
DETAILED DESCRIPTION We start with the tubular structure to which the membrane is going to be attached, for instance a Geodesic Dome, as shown in FIG. 1, or a Space Frame, FIG. 2, or other unspecified stable tubular structure.
In the preferred embodiment, per FIG. 3, the structure consists of struts 1, which are round pipes, tubes or rods that are flattened and drilled at the ends, to form the tongues 2. The struts 1 are marked with a color or otherwise coded band 42 indicating strut length, to assist in structural assembly and glazing.
FIG. 4 These struts 1 are bolted 4 together creating the hubs 3 of the structure. This type of hub 3 is very simple, angularly self-adjusting and does not require complex machining to create. Generally, these struts flex at the tongues 2, bending naturally to the angles required by the geometry of the structure. This requires the strut/tongue material to be somewhat malleable or springy.
A section through a Low Profile Hub, FIG. 5, shows a bolt 4, two washers 5 and nut 6 holding a stack 7 of struts 1 together, to form a hub of the structure. The bolt 4 also passes through a hole in the Membrane Hub Cap 8 used to seal the membrane. This hole is clamped shut between two washers 5 by the nut 6 and a coupling 9. This coupling 9 in turn holds an eyebolt 10 that can be used to suspend items (e.g. shades, tarps, platforms, equipment) from the inside of the structure. The coupling 9 can also support equipment directly.
There have been many different hubs designed for Geodesic Domes and Space Frames. This method of membrane attachment is generally independent of the type of hub used, as long as the struts are tubular.
FIG. 6 To create a Membrane Panel 17, rolls or sheets of membrane material 8 are hung or laid flat against a surface. A template 11 is placed over the membrane material 8. A Scribe 12, with a marker or cutter inserted into hole 19, rides along the outside of the template 11, on each side from end to end, between the bolts 4, tracing the outer edges 13 of the panel 17. Panel cutbacks 14 are marked by placing the Scribe 12 on the Template 11 close to the bolts 4 and using the Scribe's sloped edges 21, strike the panel's cutback edges 14 on each side of each bolt 4. The panel's cutback edges 14 comes close to, but do not overlap, the bolts 4. The Panel Index lines 15 are marked by tracing the inside corners of the Template 11 near the bolts 4. The Strut Designations 16, corresponding to Color Bands 42 on the struts of the Template 11, are written on or otherwise applied to the Panel 17. A strut designation can be as simple as a swatch of the color thus transcending language boundaries. The Panel 17 is cut out of Sheet 8, along lines 13 and 14.
FIG. 7 In the preferred embodiment, the templates are generally strut 1 triangles connected by bolts 4. Templates 11 can be other shapes for special purposes, e.g. rectangular or trapezoidal for entry ways. There is one template required for each unique facet of a structure, indicated by the color code bands 42. Since there is a repeating pattern of similar triangular facets in a Geodesic Dome or a Space Frame, relatively few templates 11 are required for a structure compared to the total number of facets of the structure. Templates 11 can be created from struts borrowed from the structure. This is what is meant by an integrated system. The structure itself can be the pattern for the membrane panels. The only additional special part required to layout the panels is the Scribe 12. Optimally, designated stand-alone templates 11 are kept for replacement panel creation or for mass production.
The front view of the Scribe 12 used to trace the template 11 is shown in FIG. 8. It has at least one hole 19 into which a marking or cutting device is inserted to mark or cut the long outer edges of the panels. Multiple holes 19 for different amounts of overlap are optional. The sloped scribe edges 21 are used to mark the panel cutbacks.
In the preferred embodiment, shown in FIG. 9, the Scribe 12 is made of thin gauge sheet metal that holds its shape, while being easily cut, formed and drilled. The ledge 22 is created by folding the sheet metal. The Scribe 12 can be fabricated from sheet metal, plastic or other suitably rigid thin material. It rides along the outside of the template 11 on its ledge 22, while a pen 20 inserted in hole 19 marks the panel's long edges on the membrane raw material 8.
FIG. 10 The resulting Membrane Panel 17, provides for a substantial panel flap 23 outside of the strut line 24 and stops a short distance 25 from overlapping the hubs 3. The strut designations 16, corresponding to the color codes on the template struts, are marked on (applied to) each end of each panel flap 23. The strut designations 16 and the panel index lines 15 are the only markings on a finished panel 17 required for installation. One benefit of this method is that the resulting panels 17 will exactly match the structure to which it is being applied. While modern industrial processes can easily be applied to creating these panels 17, the ability of the individual user to readily create their own panels is an asset, especially in third world environments, in emergency situations, for do-it-yourselfers, artists and for advertising.
The results you get with this method depend on the type of panel material used. The membrane material should be of such tensile strength that it will not significantly stretch under the tensile loads created by the clips used to attach it to the structure. Smooth materials with few flaws, produce a consistently tight and smooth surface. Some wrinkled materials have a tendency to smooth out over time with this method, under the constant application of tension, along with repeated heating and cooling cycles. UV resistance is a major consideration in panel material selection for outdoor use, generally determining the lifespan of the panels. Thermal expansion is a factor as well, generally the lower the coefficient of expansion, the more consistent the smoothness throughout the operating temperature range.
FIG. 11 shows a geodesic dome 39 in the beginning stages of assembly, with two levels of struts and one panel installed. The tubular geodesic dome 39 is readily assembled from the top 26 down, raising on its outer edge 28. Panels 18 are attached to the dome 39 as it erected, with time being given for glazing between the assembly of subsequent dome levels 27. It is advised to have one complete level assembled between the layer being glazed and the ground or floor, until the last level is complete. The bolts on the layer 27 being glazed should be thoroughly tightened before glazing. Generally, all the membrane panels for a given level 27 are installed one after the other, after which the dome 39 is raised another level 27.
FIG. 12 It is important that the dome 39 is anchored during erection and after completion, so that the glazed dome will not be blown away, should strong winds arise. This is an important issue due to the high surface area to weight ratio of this type of structure. The Zenith Anchor 30 is the only anchor required to effectively anchor a dome 39 that is ½ sphere or less. The Zenith Anchor 30 attaches the dome zenith 26 directly to the dome base center point 29. This provides a geodesic line of attachment that resists any movement away from the anchor point 29, being that the zenith 26 is locked into place in the horizontal plane (X & Y) by the geodesic arc 31, 360 degrees around the dome 39 and the geodesic line from zenith 26 to the base point 29 locks the vertical direction (Z). The Zenith Anchor 30 allows for rotation about the Z axis. This rotation can be utilized in the overall function of the dome 39 (e.g. in use as an astronomical observatory). Rotation can be locked into place with the addition of at least one anchor point 41, anywhere around the base of the dome. The Zenith Anchor 30 can also work in non-horizontal conditions: on slopes, vertical walls and upside down.
The Zenith Anchor is a very simple, yet effective method of anchoring a geodesic dome. In the preferred embodiment, shown in FIG. 13, starting from the Zenith Hub 3, an ‘S’ shape 33 connects a chain 32 that runs to a turnbuckle 34 attached to an auger anchor 35. This makes make a sturdy and adjustable Zenith Anchor running geodesically into native soil/earth 36 at the dome base center point. The auger anchor 35 can be replaced by lugs on a steel deck, an eye bolt imbedded in wood or concrete, or by weights, to name a few possibilities. The turnbuckle 34 tightens to lock the structure in place or releases tension for removal or relocation.
FIG. 14 A Zenith Anchor is not applicable to or recommended for a dome 39 with a profile greater than ½ sphere, as hereon designated by line 37. This is because the inward curvature 38 of the dome 39 and the elevated center of the sphere 40 lead to instability with a tendency of the dome to buckle below midline 37 during assembly. A dome 39 greater than ½ sphere 37 must have extra support for stability during assembly, such as lifting with a crane, multiple jacks around its perimeter or an internal column with tie downs. Anchors 41 need to be placed at hubs all around its base upon completion, for the structure 39 to be stable and self-supporting.
To initiate Glazing, referring to FIG. 11, get a Membrane Panel whose strut designations match the strut pattern of facet 18.
FIG. 15 Viewed from inside the structure, the panel 17 is laid over the struts 1, matching the panel strut designations 16 with the appropriate struts 1, as indicated by color code bands 42 and aligning the panel index lines 15 with the hubs 3. The panel should be installed with the markings facing toward the inside of the structure, so they are visible from the inside to be useful in mounting and are hidden after installation.
FIG. 16 Panel clips 43 are used to retain and apply tension to the membrane panels. In the preferred embodiment, the panel clips 43 are equal or similar to what are currently manufactured and commonly called binder clips. They are springy and exert considerable force, yet are easily opened by an average human hand. The clips 43 are opened by handles 44 that are removable. The handle ends are inserted into tubular lips 46. These lips 46 provide rounded corners 45 at the point of contact with the membrane panel and allow a rod of the appropriate size to be inserted and held in place by friction fit.
FIG. 17 To start mounting the panel, fold one of the panel flaps 23 around its strut 1, pointing inward 48 toward the center 47 of the panel 17. Attach a panel clip 43 at one end, in the manner shown in section in FIG. 18. Carefully maintain the panel 17 to strut 1 alignment, using the panel index lines 15 as the guide. Smooth the panel 17 along the strut 1 in direction 49, so that it lays flat and smooth on the strut 1, then place a second clip 50 at the opposite end of the strut 1.
FIG. 18 shows the way that a panel 17 is attached to struts 1 along an outer edge. The overlapping flap 23 is folded over the strut in direction 48 and the clip 43 is attached in a way that leaves the panel 17 tangent to the strut 1.
FIG. 19 Take the panel index 15 opposite the edge just secured and align it with the hub 3. While pulling the panel 17 tightly in direction 51, fold one of the loose panel flaps 23 around its strut 1 and place a clip 43 at this end, in the manner of FIG. 18. Fold the other loose panel flap 23 over its strut 1 and place a second clip 50 on it.
FIG. 20 Along one side, smooth the panel in direction 49 and flatten the panel 17 on the strut 1. Pull the loose end of the panel flap 23 in the direction 52 and place a clip 43 close to this end, in the manner of FIG. 18. Place a second clip 50 the same way for the other loose panel flap 23.
FIG. 21 Grab the center edge of one of the panel flaps 23 and pull 48 tightly toward the middle 47 of the panel 17. Place a clip 43 on the strut 1 perpendicular to where you are pulling and in the orientation shown in FIG. 18. Repeat this procedure on all 3 sides. If subsequently, warps occur over the panel 17 surface, go to the end of the panel flap 23 end nearest the warp and remove the clip 50. Pull the panel flap 23 in direction 52, carefully smooth the panel 17 along the strut 1 and re-attach the clip 50. Do this for as many areas as required, until warps have been minimized and the panel 17 is smooth and tight (as the material permits).
FIG. 22 is the outside view of the panel 17 just mounted. Select one of the structure facets 18 adjacent to the first panel 17 for the location of the next panel. Note the strut pattern as indicated by the color coded bands 42 on the struts 1. Get a membrane panel that matches that strut pattern.
Viewed from inside in FIG. 23, align the second panel 53 with its struts 1 and hubs 3, using the panel strut designations and panel index lines 15. Overlap and clip 43 each of the panel flaps 23 that are on bare struts 1, making sure that panel 53 lays smooth and flat along the struts 1 in direction 49, as was done with the first panel 17.
Remove the clips previously set on strut 54. Wrap panel 17 around the strut 54, pointing inward 48, as shown in section FIG. 24. Bring the second panel 53 beneath the strut 54 and overlap the first panel 17. Pull the center edge of panels 17 & 53 together tightly in direction 48 toward the center 47 of panel 17.
FIG. 25 Open the clip 43 to about the diameter 55 of the strut 44. Place a clip 43, over the middle of the strut 54, against the panels 17 & 53. Push 56 the clip 43 toward the strut 54, while maintaining tension 48 in the panels 17 & 53.
FIG. 26 Continuing to push 56 the clip 43 toward the strut 54, gradually reduce tension 48 on the panels 17 & 53, allowing the clip 43 to move to the point where the strut 54 sits between the clip lips 46 and the clip back 58, in other words “inside” the clip 43, but not so much as to allow the clip back 58 to touch the strut 54. Release the panels 17 & 53 and clip 43. When a clip 43 is properly set by this method, it can be pushed 56 toward the strut 54 and it will not move. Keeping the strut 54 within these parameters, ensures that there is tension being applied to the panels 17 & 53, as they resist the force exerted by the clip 43. If the distance 59 between the clip back 58 and the strut 54 is reduced to zero, there will be no tension applied to the panels 17 & 53 by the clip 43, because the lips 46 have reached their limits of travel and cannot exert force on the panels 17 & 53 beyond this point. A distance 59 of zero is a prime visual indicator that the panels 17 & 53 need to be re-tensioned by re-setting the clips 43, in order to maintain uniform tension throughout the membrane.
Depending on the expansion coefficient of the panel material and the air temperature at the time of installation, a tension adjustment may be required at higher temperatures, in order to have a smooth and tense panel surface over the entire operating temperature range. By pushing 56 on the clips 43, at the high end of the operating temperature, you ensure tension in the membrane panels 17 & 53 at any normal temperature.
FIG. 27 Using the method outlined above, the center clip 43 is set first. Then grabbing an end of the panel flaps 23 of both panels 17 & 53 together, pull in direction 52. With the panels 17 & 53 lying flat and smooth along 49 the strut 54, set a clip 50 near the end, in the same manner as the first clip 43. Do this at both ends of the panel flap 23.
After these three clips are in place, the remainder of most of the strut 54 length is clipped using Tension Bars. Tension Bars apply tension to the panels 17 & 53 along the length of the strut 54, reducing the total number of clips 43 needed on the structure. As shown in FIG. 28, Tension Bars consist of two clips 43 connected by two rods 61 of equal length 63 and with a diameter sufficient to produce a friction fit at points 62 with the clip lips 46. The Clip Cap 76 is fastened to the clips 43, creating a single stable unit. The Clip Cap 76 is attached rigidly to the clips 43, by adhesives on the surface of the clips 43, in the preferred embodiment or by rivets, clips, tabs, magnets, etc. Two tabs 110 on the Clip Cap 76 wrap around the rods 61 and are held in place between the rods 61 and panels 17 & 53 when installed. This serves to stabilize and mechanically restrain the Clip Cap 76. The Clip Cap 76 rides on the clips 43, but does not substantially contribute to the force exerted to the panels 17 & 53. The Clip Cap 76 can be any thin sheet material, which is flexible yet holds its shape. It is bent or folded to generally match the sides of the clips 43. The bridge rods 61 must be sufficiently rigid so that a constant force is applied to the panels 17 & 53 all along the strut 54. There is an optimal length 63 and rigidity for the rods 61. A rod 61 that is not rigid enough will tend to bend under the loads, allowing the panel edges to bow toward the center of the panel and resulting in warps in the panels 17 & 53. Rod lengths 63 can vary in length to facilitate effective coverage of the strut 54 with the fewest possible clips 43.
FIG. 28A shows the finished Tension Bar 60 assembly with handles 44 still in place.
FIG. 29 To install a Tension Bar 60, squeeze it open and place it closely adjacent to, but not touching, the end clips 50. Placing Tension Bars 60 does not require pulling and pushing like the first three clips 43 & 50. Instead, they are merely set in place. They assume the same clip lip positions, relative to the strut, as the first three clips. Several additional Tension Bars 60 may be required to cover the entire strut 54, depending on the relative lengths of the Tension Bars 60 to the struts 54. In the preferred embodiment, three Tension Bars 60 per strut 54 are used. The objective is to leave no gap larger than a clip between clips 50 and Tension Bars 60, so that tension is applied to the panels 17 & 53 more or less uniformly along the strut 54.
FIG. 30 shows a finished installation with the middle clip 43 in FIG. 29 removed and replaced by a tension bar 64. The handles are removed for a more uniform finished look and saved for future use.
The procedure described above is repeated for every facet desired on the tubular structure. You either have abutting panels or an edge, FIG. 18. One of these two ways of panel attachment is used for every panel on a structure. An edge generally should be covered by Tension bars for uniform tension, restraint along the edge and a finished look.
With this method, the resulting membrane surface exhibits more or less uniform tension across the structure, assuming all clips exert approximately the same force. FIG. 31 illustrates the forces involved with the system in equilibrium. The clip 43 applies the same force 65 tangentially to both sides of the strut 1. The tensile force 66 in the panels 17 & 53 is equal to force 65 exerted by the clips. This force 65 on the strut 1 is generally directed “into” the clip 4, with the “vertical” component 99 trying to push the strut 1 into the clip 43, but is resisted by the panels 17 & 53. This resultant force 99 is the clips grip on the struts. The horizontal component 106 of the clip force is resisted by the panels. The relative size of these component forces 106 and force 99 vary depending on the location of the strut 1 in the clip 43. The deeper the strut 1 is in the clip 43, the greater the force 99, thus the tighter the grip. However, the overall the tensile force 66 in the panel is equal to the force 65 exerted by the clip, which is more or less constant.
FIG. 32 The direction 68 of the wrap of the panel flap 23 around the strut 1 is a consideration, depending on the use of the structure. Wrapping the panel flaps 23 in an upward direction 68 around the strut 1 collects external runoff 67, channeling the water 107 toward the hubs. This can be an asset in greenhouse applications, where uncapped hubs allow this water 107 inside 71 of the structure. This is problematic for dwelling or storage. This wrap also tends to collect interior condensation runoff 70 between the panel flaps 23 and the upper panel 17, seeping down to the strut 1, leading to corrosion and the accumulation of dirt, etc. An upward wrap is required on lower panel 53 to accommodate the Hub Cap.
FIG. 33 A downward wrap 68 sheds runoff 67. The water 107 falls down the slopes. There is minimal accumulation of water. The downward curvature 68 also protects the struts 1 from interior condensation runoff 70, dirt accumulation, and the subsequent corrosion.
FIG. 34 For most applications, where the membrane structure sits directly on the natural ground 36 or prepared surface, the panels 17 curve around the base struts 1 to the inside 71 and the panel flaps 23 are clipped 43 as per FIG. 18. It is important that the panel 17 lays smoothly on the strut 1 and in proper alignment with the struts and hubs. The panel flap 23 is taped 119 to panel 17 to help prevent accumulation of water/condensation and dirt around the strut 1.
Panel clips 43 can be set at various angles to the struts 1 and panels 17. The usual angle is the one that bisects the interior angle between the adjacent panels or panel and base 36. The clip angle can be adjusted by grabbing the membrane panel that is looping around the strut, pulling tight then slightly releasing, while the clip grip is slightly released and repositioned to the desired orientation. The membrane and clip are allowed to slide slightly relative to each other, while tension is maintained.
In FIG. 35, as viewed from the inside of structure at the hub 3, there are gaps 72 between the membrane panels 17 & 53. A circular Hub Cap 73, usually made of the same material as the panels 17 & 53, is placed under the upper panels 17 and on the outside of at least one lower panel 53, so that precipitation runoff is diverted over the gaps 72, similar to a typical roofing shingle. The Hub Cap 73 is cut to such a radius 108 that its outer edge 109 is just beyond the nearest panel clip 43 when installed. This is so that the Hub Cap 73 and the membrane panels 17 & 54 are clipped tightly and securely together, to help create an effective weather seal.
When a vertex has a strut 1 pointing vertically down, as shown in FIG. 35A, leakage can occur in the transition zone 113 from underlay to overlap. This zone is tilted sideways and provides a channel for leakage into the dome. This leakage can be stopped by applying a layer of sealant in this zone 113 between panels 17 and the hub cap 73 and tightly clamping these pieces together with the panel clip 43. Filling the lower portion of the panel depression covering area 113 with sealant from the outside, also be done to help ensure a seal. This is the only location where sealant may be required. A water test should be run after installation to find and eliminate leakage sources, if being water proof is important.
A section through the hub 3, FIG. 36, shows how the hub cap 73 is placed such that its top portion 74 is under the upper panels 17 and the bottom portion 75 is over the lower panel 53. A small cut is made at the center of the hub cap 73, so that the bolt 4 at the center of the hub 3 can pass through. This hole is clamped shut between two washers 5, a nut 6 and a coupling 9. Runoff 67 is effectively diverted over the gaps 72 at the ends of panels 17 and 53.
FIG. 37 After the clips and tension bars 60 are in place on the strut 1, the handles are removed, stored for future re-use and excess panel flap 23 material can be trimmed off. It is advisable to leave enough panel flap 23 to easily grip for re-tensioning. Leaving a very small gap 110 between tension bars 60 provides a clean and nearly continuous visual line along the struts, while allowing for thermal expansion. This gap 110 can be covered by extending the clip caps 76 beyond the ends of the clips 43 and then overlapping adjacent tension bars 60. Tension bars 60 can also be used as a chase for small Power, Control, Supply or Data lines 77 and as a mount for switches, controls, lights and other devices.
FIG. 38 This method of membrane attachment readily allows the covering of projections from a structure 81, such as a walk-thru entry 79 or vent 80, with the same continuously tensed surface as the rest of the structure. In the preferred embodiment, these openings are formed from struts 1 of the same material as the parent structure 81 per FIG. 3, but of different lengths and tongue 2 orientations.
FIG. 39 A vent 80 can be created from a tetrahedral strut arrangement attached to the parent structure 81 at two points 82 and nesting in the structure. It is actuated by a tension element (rope, chain, cable, hydraulic or electric actuator, etc.) on the inside of the parent structure 81. This is called a TetraVent.
FIG. 40 As viewed from the outside of the parent structure 81, the top facet of the TetraVent 80 as defined by struts 83, matches the facet of the parent structure 81 beneath it. This tetrahedral facet is the door of the TetraVent 80. The forth hub 84 of the tetrahedron and its struts 85, nest into the parent structure 81, serving to orient and center the TetraVent 80 upon closing. In most locations on a dome, gravity forces the TetraVent 80 to close by default. The tetrahedron is attached to the parent structure 81 at two points 82 by short tensile elements 88 (chain in the preferred embodiment or rope, cable, etc.). This allows pivoting rotation around the line between these points 82, while securing the vent to parent structure 81. This is the TetraVent hinge.
FIG. 41 is the side view of the TetraVent structure showing the struts 85 of the tetrahedron nesting into the parent structure 81. These struts 85 reach over and attach above the vent door struts 83 as detailed in FIG. 41A. This arrangement allows the door struts 83 of the TetraVent and parent structure 81 to mate directly and seal. These struts 85 are connected at the forth hub 84 using an eye bolt 10, to which is connected to an actuator line 86 (rope, chain, cable, etc.), that can be used to open and close the TetraVent. The attachment points 82 are detailed in FIG. 41A, which shows how the TetraVent 80 is attached to the parent structure 81 by means of chain 88 clamped between washers 5 by nuts 6 on opposing (head to head) bolts 4, in the preferred embodiment.
Referring back to FIG. 39, after the TetraVent 80 structure is attached, the membrane panel 87 is attached to the swinging edges 120 of the vent door by a row of tension bars 60 that mate with the row of tension bars 60 along the parent structure opening 121 when closed. The panel 87 is first attached to the vent door along the swinging edges 120 first, in a manner similar to FIG. 18, then to the parent structure 81 per the method for abutting panels, described starting at FIG. 23, along the hinge created between points 82.
FIG. 42 is a section through the vent hinge. The section line is shown on FIG. 39. The TetraVent membrane panel 87 curves over and around the vent door strut 83 and is attached to the parent structure 81 strut, along with the adjacent panel 17, by clips 43 and tension bars 60 on the inside 19 of the structure in the manner previously described starting at FIG. 25. Tension in the vent panel 87 is created by the clips 43 and tension bars 60 on this parent structure 81 strut.
FIG. 43 is a section through the vent door jamb where strut 83 and the matching side of the parent structure 81 come together when closed. The continuous rows of clips 43 and tension bars 60 on these mating struts 80 and 81 provide durable edges that overlap when shut, as shown, to help prevent leakage into the structure and center the door when shut.
FIG. 44 is a section thru a dome 39 showing two TetraVents 80 & 90 near the zenith 26. The left TetraVent 80 is opened using an actuator line 86 (rope, chain, cable, etc.) connected to the intruding tetrahedral vertex 84. This actuator line 86 runs along the inside of the dome 39 toward ground level 36 thru eye bolts 10 attached to the dome hubs 3 and is tied off to an eye bolt 10 at a convenient location. The actuator line 86 can be replaced by a remote controlled electro-mechanical or hydraulic actuator attached to a nearby hub 3. The right TetraVent 90 is locked into closed position with a locking line 89 hooked back to the Zenith Anchor 30 chain.
FIG. 45 External shades 91 may be attached to a dome 39 over the structure and membrane panels with this system using low profile hubs as detailed in FIG. 5, over most of the dome and a ring 92 of hitching post hubs 93 around the dome perimeter 39 at a convenient height. These shades 91 and their top tie lines 94, when pulled tight between the hitching post hubs 93 to which they are attached, describe a geodesic (great circle) arc over the dome 39. These geodesic lines are very stable, in effect locking the shades location on the dome 39. It is this arc that is used to set the location of the shade 91. The lower ties 95 are tied to the base and other hitching post hubs 93 on this ring 92 in order to flatten the shade 91 and prevent it from flapping in the wind. These shades 91 can serve several uses. They can provide shade for the interior and provide added protection in storm conditions.
As shown in the elevation view in FIG. 46, shade tie downs 94 & 95 can be made anywhere along the dome base by using “S” hooks 96 attached to the base struts 1 and then tied off to a hitching post 93. This elevation shows a dome 39 that is elevated above ground 36 using feet 116.
FIG. 47 The “S” hook 96 attaches to the base of the dome around the strut 1 to secure the tie line 94. On loose ground/soft earth, these hooks 96 can be laid flat on the ground 36, slid under the dome sideways between the strut 1 and the ground 36, then rotated and pulled into the upright vertical position shown. FIG. 47A, On a hard surface, adding feet 116 to the hubs 3 around the base gets the struts 1 off the surface and facilitates placement of the “S’ hooks and the shades and help minimize the impact to the base surface 118 by the dome. A rubber foot pad 117 is added on the bottom of the foot 116 to help protect relatively delicate surfaces 118, like basketball courts or painted/epoxy floorings. The foot shown is made of structural steel angle shape.
In the preferred embodiment, the Hitching Posts hubs 93 are constructed as shown in FIG. 48, with threads extending inside 71 and outside 100 of the structure. This enables two-way extensions from the hub via couplings 9. These extensions can be as simple as a bolt 4 (to cap the coupling as shown) or an eye bolt 10 to equipment such as antennas, lighting, camera, speakers, motion detectors, etc. The inside eye bolt 10 can be used to hang ceiling panels and wall partitions and run the TetraVent actuator, among other things. This hub 93 uses a threaded rod 105 at its core, onto which nuts 6 and washers 5 secure the stack 7 of struts 1 and clamp seal the membrane hub cap 8 between two washers 5. At dome zenith, detailed in FIG. 48A, a zenith cap 112 is installed on a hitching post hub, fastened with a nut 6 and washer 5 on the threaded rod 105 over a hub cap 8, to help shed water, etc. at this horizontal location. This cap 112 can be bowl shape, as shown, conical or other shape with a rim 115 that is circular or fits with the geometry of the dome (e.g. hexagonal or pentagonal).
FIG. 49 A triangular structural facet 18 can be subdivided to create non-triangular openings 104, for this membrane panel system, to create openings for doors, hatches, ports, mounts for equipment and other accessories. Shorter struts 101 are attached to primary structural facet struts 1 by way of perforated straps 102 clamped down and held longitudinally in place along the struts 1 by set screws 103. This type of connection is not intrinsically stable like a standard geodesic or octet strut arrangement and should therefore be used sparingly, triangulated where possible and the application thoroughly tested for stability under loads. In the preferred embodiment, these smaller struts 101 are made in the same way as the regular structural struts 1, per FIG. 3.
A section view of this connection, FIG. 50, shows how the shorter strut 101 is attached to strut 1 by way of a strap 102 that wraps around the strut 1 and is clamped down by a bolt 4, nut 6 and two washers 5.
In the front view of the connection, FIG. 51, you can see how the strap 102 is held in place along the strut 1 by a set screw 103 on each side along with the clamping pressure of the bolt 4, washers 5 and nut 6.
FIG. 52 Both types of hub 3 are designed so that an internal eye bolt can be available at every vertex of the parent structure 81, enabling ceiling panels 106, screens 107 and wall partitions 97 to be easily hoisted and securely attached to the structure. These elements can be attached directly to the hubs 3 or by lines 94 (rope, cables, chains, et al.) to create rooms, hallways and other interior spaces. This system allows for great flexibility in the use of a dome's interior clear span space. It is easily reconfigurable and can use a wide variety of materials.
