This application relates generally to architectural systems and more particularly to node and strut configurations.
Despite the many advances in materials over the past several decades, and the continuing interest in alternative building styles such as dome structures, the use of spaceframes in construction continues to be rather limited. Although node and strut systems have been devised and used by some, only very limited types of geometries, generally those based on the cube or pyramid, have achieved widespread use.
One noteworthy exception is the pioneering work of Steve Baer, who on 27 Mar. 1973 was issued U.S. Pat. No. 3,722,153 (“Structural System”). The Baer patent teaches rigid, lightweight systems of nodes and struts, but does not provide any mechanism for ensuring rigid engagement between nodes and struts in a complex spaceframe. The teaching in the Baer patent is likewise limited by the small number of varieties of base triangles included.
Further, useful advances were taught in U.S. Pat. No. 5,265,395 (“Node Shapes of Prismatic Symmetry for a Spaceframe Building System”) issued 30 Nov. 1993 to Haresh Lalvani. The Lalvani patent teaches nodes and struts of various geometries, but does not teach any system for using struts to rigidly couple adjacent layers. A similar design, simpler than Lalvani's but also lacking inter-layer triangulation, is shown in
Those skilled in the art have overlooked substantial benefits that might be achieved in economies of mass production, versatility, high rigidity, low weight and/or ease of assembly in architectural systems incorporating golden geometry. It is to these opportunities that the present invention is directed.
The present invention is an architectural system that, in its most basic form, includes a triangular base which engages an extension. The base includes three “complete” struts (defined in the detailed description below) substantially aligned along three respective axes. These axes each intersect each other to form a triangle defining in a base plane. The triangle's vertices each correspond to a respective nucleus (described below) of nodes called A, B and C. This forms three base angles (called CAB, ABC, and CBA). Angle CAB has a positive value about equal to [j×20.9°+k×31.7°+m×36°+n×37.4°], where j, k, m and n are each an integer less than three. Angle ABC also has a positive value about equal to [q×20.9°+r×31.7°+s×36°+t×37.4°], where q, r, s and t are each an integer less than three. Subject to certain geometric restraints such as the necessity for the interior angles of a triangle to total 180°, these eight coefficient values can vary somewhat independently.
At least one of the base triangle struts comprises at least two rigid pieces able to move apart so as to produce a strut elongation. In a complex spaceframe where each node has a position constrained by struts already engaging it, each new strut installed should desirably have such a length correction mechanism so as to permit positive (areal) engagement with its nodes.
The extension comprises (at least) a fourth complete strut substantially aligned along a fourth axis that is neither coplanar with nor orthogonal to the base plane. The fourth axis, in fact, forms a substantially acute angle >3° with the base plane. (Although additional extension struts may be orthogonal, adequate structural triangulation might not be achieved without at least one such acute angle.)
These and various other features as well as additional advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.
Although the examples below show more than enough detail to allow those skilled in the art to practice the present invention, subject matter regarded as the invention is broader than any single example below. The scope of the present invention is distinctly defined, however, in the claims at the end of this document.
Numerous aspects of spaceframe architecture that are not a part of the present invention (or are well known in the art) are omitted for brevity, avoiding needless distractions from the essence of the present invention. For example, this document does not include much detail about material selection or node design, except where the inventor has observed opportunities for a synergy.
Definitions and clarifications of certain terms are provided in conjunction with the descriptions below, all consistent with common usage in the art but some described with greater specificity. As used herein, an “axis” of a strut refers to a line segment very closely aligned with the strut. An axis has a “length,” ordinarily greater than that of the corresponding strut, bounded by nuclei of two nodes with which the strut engages. As used herein, a “nucleus” of a node is a point (usually within the node) aligned with the axes of struts that engage with the node. For nodes that are not substantially round, a nucleus will be approximately equidistant from two or more node surfaces that each engage a strut. As used herein, a “radius” of a node refers to a distance measured from a nucleus to a farthest surface from the nucleus. Thus, the term is defined even for nodes of irregular shape. Two angles are “substantially equal” herein if they are within half a degree. Other quantities are “substantially equal” if they are within 0.5% of each other.
A “complete” strut is one that substantially surrounds its corresponding axis for the entire length between the nodes engaged by the strut. Such a strut will distribute an axial tension or compression on opposing sides of the axis. An arcuate or other “incomplete” strut, by contrast, will bow further away from the axis under axial compression. This greatly reduces the rigidity of the system, or necessitates a needless increase in strut weight.
Turning now to
It will be appreciated by those skilled in the art that the structure of
Struts 524 and 528 are aligned along respective axes that form a 37.4° angle. Struts 524 and 561 are aligned along respective axes that form an angle about equal to 20.9°+20.9°+31.7°+37.4°. Thus it would appear that struts 524, 528, 561 (with nodes 520, 530, 540) would form a suitable base triangle of the present invention, in a vertical plane. Unfortunately, this design has a noteworthy weakness: All of the direct extensions from this base triangle extend either along within the same plane (i.e. struts 525, 527 to node 550) or perpendicular to the plane (i.e. “aligned substantially parallel to” strut 531). Applicant has determined that such designs are often not adequately rigid to resist a shear force parallel to the base plane. Such designs can therefore be susceptible to vibration, deformation and degradation that can have severe consequences in larger scale applications.
Struts 612, 614, 624 are substantially aligned along respective axes that form an isosceles triangle with two interior angles of about 20.9° and one of about 140.2°. (Note that this is equal to 31.7°+31.7°+37.4°+37.4°.) A triangular base of the same size and shape is formed by strut 624 with struts 622, 634.
Struts 631, 632, 642 are substantially aligned along respective axes that form an isosceles triangle with two interior angles of about 72° and one of about 36°. (Note that this corresponds to a triangle with m=s=2 and j=k=n=q=r=t=0, in terms to the formula given in the summary.) A larger base triangle forming these same angle is formed with corners in nodes 610, 640, 670. Note that the longer sides of this base triangle are very long in comparison to their thickness. Rigidity is maintained, however, because each is a “supported strut,” one that includes a radially protruding extension (such as strut 631) generally supporting the mid-section of the supported strut. Finally, another advantage of frame 600 is the small variety of struts required to build it. As shown, only four lengths of (unsupported) struts are used.
Three of the nodes of pentagonal wall frame 600 are re-used in
Axes 1031, 1041, 1051, 1061, 1071, 1081 are each longer than L by about 5.14%. Each is substantially aligned with a strut about as long as L shown in structure 900, of which there are 16. Similarly there are five struts in structure 900 having a maximum length, each aligned along a respective axis such as axes 1042, 1052, 1082. Structure 900 also contains 16 basically identical struts somewhat shorter than those of maximum length, aligned along axes like 1018, 1048, 1058, 1078, 1088. And finally, structure 900 contains eight basically identical, medium-length struts aligned along axes like 1045, 1085.
Struts or axes having the same last digit, within
The base of the system 1100 is a pentagon having five sides (including axis 1112) and five points (including nuclei 1170, 1180). A base triangle of the present invention includes axes 1112, 1117, 1127 and nuclei 1170, 1180 and angles as shown within that triangle.
One surface axis, the one just below axis 1137, is not shown so as to reveal the position of a horizontal axis 1132 the same length as that of base axis 1112. This horizontal axis 1132 is part of two base triangles of the present invention, with angles as shown. The complete structure includes a total of twenty horizontal axes like 1112, 1132. Twenty substantially identical struts (not shown) aligned along these axes provide four pentagonal floors within structure 1100. If desired, each of these simple floors can be augmented by using a vertically compact pentagonal frame like frame 600 of
Node 1210 is an aluminum polyhedron having a threaded hole 1211 in each exterior side. When bolt 1299 engages node 1210 as indicated, the angled portions of the sides 1291, 1292 yield slightly to permit a solid engagement between the engagement portion 1293 of the strap and the top surface of the node 1210 even if the strut 1290 is slightly too long or short. Even while providing this flexibility, strap is wide, thick, and short enough as shown to make the overall node/strut joint highly rigid so long as the disengaged strap position (i.e., the position along axis 1297 at which the strut has axial stresses of 1 Newton or less) is within about R/50 of node 1210, where R is the radius 1298 of node 1210.
The closest successive holes 1211 of node 1210 are 36 degrees apart (although some sides 1212 lack engagement holes so as to simplify node manufacture). Node 1210 is therefore also capable of supporting rigid angles of 72 degrees and 108 degrees, the same ones required for structure 700 (of
More sophisticated engagement mechanisms are available. For example, U.S. Pat. No. 4,193,706 (“Bolt Connections Between Tubular Rods and Junctions in Three-Dimensional Frameworks”) issued 18 Mar. 1980 to Eberlein et al. teaches one such system. Similar systems are available for purchase from Mero Structures, Inc. in Menomonee Falls, Wis. (262-255-5561,www.mero.com).
Alternatively characterized, a first embodiment of the present invention includes a triangular base (such as 101) which engages an extension (such as 102). The base includes three complete struts substantially aligned along their respective axes. These axes each intersect each other to form a triangle contained in a base plane. The triangle's vertices each correspond to a respective nucleus of nodes called A, B and C. This forms three base angles (called CAB, ABC, and CBA). Angle CAB has a positive value about equal to [j×20.9°+k×31.7°+m×36°+n×37.4°], where j, k, m and n are each an integer less than three. Angle ABC also has a positive value about equal to [q×20.9°+r×31.7°+s×36°+t×37.4°],where q, r, s and t are each an integer less than three. Note that these angular constraints can impose size limitations on the nodes. For example, the third node (C) engages the second and third complete struts and must be large enough to maintain the third base angle BCA at a positive value less than 60°. Note also that these angular restraints permit a great variety of combinations. For example, j, n, q and t may all be even in a given base triangle.
At least one of the base triangle struts comprises two or more rigid pieces (such as 1289, 1299) able to move apart so as to produce a strut elongation. The extension comprises a fourth complete strut substantially aligned along a fourth axis forming a substantially acute angle with the base plane.
In a second embodiment, the fourth axis forms an angle with the first, second or third axis that is substantially equal to a reference angle. The reference angle is selected from a group consisting of 13.3°, 15.5°, 20.9°, 22.2°, 31.7°, 35.3°, 36°, 37.4°, 37.8°, 41.8°, 44.5°, 45°, 54.7°, 58.36°, 60°, 63.4°, 65.9°, 69.1°, 70.5°, 72°, 75.5°, 76.7°, 79.2°, 82.2°, 90°, 97.8°, 100.8°, 103.3°, 104.5°, 108°, 109.5°, 110.9°, 114.1°, 116.6°, 120°, 121.7°, 125.3°, 135°, 135.5°, 138.2°, 142.2°, 142.6°, 144°, 144.7°, 148.3°, 155.9°, 157.8°, 159.1°, 164.5°, and 166.7°. The extension (such as 102) comprises a polygon (such as a triangle or quadrilateral, see
In a third embodiment, one of the struts (such as 170) has a maximum diameter D (such as 1288) and one of the nodes (such as 110) has a radius R (such as 1298) that is not less than D/2. The struts are each primarily composed of a non-metallic material (such as wood). Each of the base's nodes includes couplings engaging two of the struts of the base triangle. Each of the couplings is capable of retaining its strut in a fixed position relative to the node, even under a tension of at least 100 Newtons along the axis therebetween. This is optionally accomplished by providing load surfaces (such as 1215, 1216) on each node and access surfaces (such as 1295, 1296) on each strut. (These access surfaces are those configured to exert force each on a respective one of the load surfaces so as to resist an axial movement of the strut relative to the node.)
All of the structures and methods described above will be understood to one of ordinary skill in the art, and would enable the practice of the present invention without undue experimentation. It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this disclosure is illustrative only. Changes may be made in the details, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. Although the preferred embodiments described herein are largely directed to conventional fasteners for node/strut couplings, it will be appreciated by those skilled in the art that many teachings of the present invention can be applied to other types of couplings without departing from the scope and spirit of the present invention.
Number | Date | Country | |
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Parent | 10099775 | Mar 2002 | US |
Child | 12271744 | US |