Beam connector for arch structure

Abstract

Structural connectors used as a component to construct an arch including a plurality of closely adjacent, polygonal rows of stringer beams. The multiple row polygonal arch is a low-cost, general purpose support structure for bridges, shelters and arbors applicable to many cost-, time- or environmentally-sensitive situations. The structural connectors may be a Y-shaped connectors with three brackets, two upper brackets and a lower bracket, which collectively enable a union of three beams forming one node of the multiple row polygonal arch. Using these Y-shaped connectors to join the beams at each node creates the arch structure, and additionally provides the features of cantilevering, modularity, generic component shape, reusability and safety. Structural connectors are applicable to a variety of structures such as pedestrian and vehicular bridges, shelters, arbors, as well as jewelry, furniture and toys. Other aspects, embodiments, and features are also included.

Claims

1. A Y-shaped structural connector, comprising: a central structure forming a body defining a vertical plane perpendicular to a vertical midplane of the Y-shaped structural connector; a first top bracket connected to the central structure and forming a first arm of the shaped structural connector having a first upper surf ace extending downward at an angle on a first side of the vertical midplane relative to an upper transverse plane defined by a top of the Y-shaped structural connector to form a surf ace of the first top bracket retaining a springer beam therein; a second top bracket connected to the central structure and forming a second arm of the Y-shaped structural connector, the second top bracket having a second upper surface extending downward at an angle on a second side of the vertical midplane relative to the upper transverse plane to form a surface of the second top bracket configured to retain a springer beam thereby; a first bottom bracket forming a foot of the Y-shaped structural connector and having an upward facing surface defining a lower transverse plane parallel to the upper transverse plane and perpendicular to the vertical plane of the central structure and the vertical midplane; and a second bottom bracket positioned parallel to the first bottom bracket; wherein the first top bracket is a mirror image of the second top bracket relative to the vertical midplane of the Y-shaped structural connector.

2. The substantially Y-shaped structural connector of claim 1, wherein at least one of the top brackets is one of L-shaped, U-shaped, or configured with fully enclosed sides.

3. The substantially Y-shaped structural connector of claim 1, wherein the transverse notch comprises a notch floor.

4. A Y-shaped structural connector, comprising: a first set of two top brackets forming respective arms of the Y-shaped structural connector, each top bracket in the first set of top two brackets aligned with the other top bracket so that they are mirror images of each other relative to a vertical midplane of the Y-shaped structural connector, each top bracket having an upper surface that extends downward at an angle on each side of the vertical midplane of the Y-shaped structural connector relative to an upper transverse plane defined by a top of the Y-shaped structural connector to form one surface of each top bracket for securely retaining a stringer beam therein; a second set of two top brackets positioned in a plane parallel to the first set of two top brackets; a bottom bracket forming a foot of the Y-shaped structural connector; and a central structure forming a body of the Y-shaped structural connector for rigidly interconnecting the bottom bracket to the first set of two top brackets and the second set of two top brackets, the central structure defining the vertical plane perpendicular to the midplane and the upper transverse plane, the bottom bracket including an upward facing surface that defines a lower transverse plane parallel to the upper transverse plane and perpendicular to the vertical plane of the central structure and the vertical midplane; wherein the two top brackets are located on one side of the vertical plane of the central structure and the bottom bracket is located on the other side of the vertical plane of the central structure, such that stringer beams inserted into the first and second set of top brackets are caused to extend out in opposite directions from the central structure and in a direction towards the bottom bracket transverse plane.

5. Y-shaped structural connector of claim 4, further comprising a first transverse notch in the pair of notches formed between at least the two top brackets of the first set of two top brackets for enabling a transverse beam to connect substantially Y-shaped structural connectors positioned in corresponding locations in adjacent arch rows.

6. The substantially Y-shaped structural connector of claim 5, wherein the transverse notch comprises a notch floor.

7. The substantially Y-shaped structural connector of claim 4, wherein at least one of the top brackets in the first set of two top brackets and the second set of two top brackets is L-shaped.

8. The substantially Y-shaped structural connector of claim 4, wherein each top bracket in the first set of top brackets and each top bracket in the second set of top brackets is U-shaped.

9. A Y-shaped structural connector, comprising: two top brackets forming respective arms of the Y-shaped structural connector, each top bracket aligned with the other top bracket so that they are mirror images of each other relative to a vertical midplane of the Y-shaped structural connector, each top bracket having an upper surface that extends downward at an angle on each side of the vertical midplane of the Y-shaped structural connector relative to an upper transverse plane defined by a top of the Y-shaped structural connector to form one surface of each top bracket for securely retaining a stringer beam therein; a first bottom bracket forming a first foot of the Y-shaped structural connector; a second bottom bracket positioned parallel to the first bottom bracket and forming a second foot of the Y-shaped structural connector; and a central structure forming a body of the Y-shaped structural connector for rigidly interconnecting the two top brackets to the first bottom bracket and to the second bottom bracket, the central structure defining the vertical plane perpendicular to the midplane and the upper transverse plane, the first bottom bracket and the second bottom bracket each including a respective upward facing surface that defines a lower transverse plane parallel to the upper transverse plane and perpendicular to the vertical plane of the central structure and the vertical midplane; wherein the two top brackets and the first bottom bracket are located on one side of the vertical plane of the central structure and the second bottom bracket is located on the other side of the vertical plane of the central structure.

10. The substantially Y-shaped structural connector of claim 9, further comprising a transverse notch formed between the two top brackets for enabling a transverse beam to connect Y-shaped structural connectors positioned in corresponding locations in adjacent arch rows.

11. The substantially Y-shaped structural connector of claim 10, wherein the transverse notch comprises a notch floor.

12. The substantially Y-shaped structural connector of claim 9, wherein at least one of the top brackets is one of L-shaped, U-shaped, or configured with fully enclosed sides.

Description

DRAWINGS

(1) FIG. 1A is a perspective view of one embodiment of the invention showing U-shape type top and bottom brackets.

(2) FIG. 1B is a perspective view of another embodiment of the invention showing L-shape type top and bottom brackets.

(3) FIG. 1C is a perspective view of another embodiment of the invention showing Fully-enclosed type top and bottom brackets.

(4) FIG. 1D is a perspective view of yet another embodiment of the invention showing Wing type top brackets with a U-shaped type bottom bracket.

(5) FIG. 1E is a perspective view of an embodiment of the invention showing the connector configured without a transverse notch between the two top brackets. This embodiment is illustrated with exemplary Wing type top brackets and an L-shape type bottom bracket.

(6) FIG. 2 is a perspective view of a single row polygonal arch structure created with the invention constructed using Y-shaped connectors according to the present invention.

(7) FIG. 3A is a front perspective view of one node of a double row polygonal arch created with the invention which shows the invention with two stringer beams inserted into the top brackets, one stringer beam inserted into the bottom bracket and a transverse beam inserted in the transverse notch.

(8) FIG. 3B is a front view of one node of a double row polygonal arch showing the use of a triangular shim to allow rectangular-ended beams to be inserted into the top brackets.

(9) FIG. 4A is a front perspective view of one embodiment of the present invention shown as an assembly of the three primary elements: top brackets, a bottom bracket, and a central structure.

(10) FIG. 4B is a rear perspective view of the invention shown in FIG. 4A.

(11) FIG. 5A is a perspective view of one embodiment of the invention with configurable vertical spacing, showing a central structure that has vertical slots which allow the bottom bracket to be selectively fixed at one of a variety of distances from the top brackets. In this figure, the bottom bracket is shown at the lower end of the range of travel.

(12) FIG. 5B is a front perspective view of the invention shown in FIG. 5A with the bottom bracket at the middle of the range of travel.

(13) FIG. 5C is a front perspective view of the invention shown in FIG. 5A with the bottom bracket at the top of the range of travel.

(14) FIG. 5D is a rear perspective view of the invention shown in FIG. 5A, showing use of bolts to attach the bottom bracket to the central structure through the two slots.

(15) FIG. 6 is a front view of an embodiment of the present invention illustrating the top brackets connected to the central structure of the Y-connector with hinges.

(16) FIG. 7A is a perspective view of an embodiment of the invention with the bottom bracket configured with a chaining hook.

(17) FIG. 7B is a side view an embodiment of the invention where two Y-shaped connectors with a chaining hooks are nested, with the chaining hook of one connector resting on the notch floor plate of the adjacent connector.

(18) FIG. 8 is a perspective view of the building block established by the invention: a construction module that interlocks with other identical modules to create a double row of polygonal arches. The illustration shows the Side-Braced embodiment of the connector configured with the L-shape type top brackets and the Fully-enclosed type bottom bracket attached to a stringer beam forming a single construction unit.

(19) FIG. 9 illustrates a front perspective view of an Abutment connection bracket according to the present invention, including a stub beam, a locking angle and a support brace with a springer building block.

(20) FIGS. 10A, 10B, and 10C are side views illustrating a sequence where a springer building block is being lowered onto the abutment. FIG. 10A shows the initial position of the locking angle when the springer building block starts to be lowered onto the abutment. FIG. 10B shows the rotation of the locking angle as the stub beam slides into the top bracket of the springer building block. FIG. 10C shows the final positions of the locking angle and springer building block.

(21) FIG. 11 is a perspective view of a cantilevered assembly sequence using building block modules created with the invention.

(22) FIG. 12 is a perspective view of a tied arch created according to the invention.

(23) FIG. 13 is a perspective view showing a two arch structure created using Y-shaped connectors according to the present invention where a transverse beam is used at each node to join the arches together.

(24) FIG. 14A shows one embodiment of a Y-shaped connector for 3-row polygonal arches. Shown is a Type A connector which has two top brackets and two bottom brackets.

(25) FIG. 14B shows another embodiment of a Y-shaped connectors for 3-row polygonal arches. Shown is a Type B connector which has four top brackets and one bottom bracket.

DETAILED DESCRIPTION

(26) The description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts and features described herein may be practiced. The following description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details.

(27) Referring to FIG. 1A, one embodiment of the invention is a Y-shaped structural connector 100 having three U-shaped brackets designed to bind three stringer beams to the union created by the connector. One U-shaped bracket is located on each arm of the Y. Each of the brackets 110 and 112 form the upper arms 1L, 1R, respectively, of the Y shaped connector 100. Each of these brackets 110, 112 binds the end of a stringer beam to the connector 100. The top brackets are aligned with each other so that they are mirror images of each other relative to the vertical, front-to-back midplane 42 of the connector 100. The U-shaped bracket 114 forms the bottom arm 2 of connector 100. Bracket 114 binds the midsection of a third stringer beam to the connector 100. The bottom bracket 114 is aligned with the top brackets 110 and 112 so that a beam fully inserted into either top bracket 110, 112 will slope toward the level of the bottom surface 116 of the bottom bracket 114. Both top brackets extend downward at an angle 40 that is greater than zero from the transverse plane 43 of the connector 100. The transverse plane 43 of connector 100 is always parallel to the bottom surface 116 on which the beam inserted in the bottom bracket 114 or the tangent to the lowest point of the beam, if the beam is cylindrical.

(28) In the FIG. 1A embodiment, the two top brackets are separated by a space, a transverse notch 3, which enables a transverse beam to be inserted into the connector 100.

(29) FIGS. 1A-1E illustrate five embodiments of the inventive connector 100 illustrating different types of brackets and transverse notch options. FIG. 1A shows U-shaped brackets 110-114, which allow the beams to enter the top brackets from below and to control the lateral movement of the beams without fasteners. FIG. 1B shows L-shaped brackets 120, 122, and 124 in a connector 100 which allow the beams to enter the top brackets 120, 122 from the side as required for the top three beams of an arch assembled by cantilevering. The bottom bracket in connector 100 is shown at 124. Bolts, screws or other fasteners are required to keep the beam in place in L-shaped brackets. FIG. 1C shows Fully-enclosed brackets 130, 132, and 134 in a connector 100 which are used in applications where the ends of the stringer beams require protection from the weather, e.g., with bamboo stringer beams. The top brackets are shown at 130 and 132, and the bottom bracket is shown at 134. FIG. 1D shows Wing type top brackets 140 and 142 in a connector 100. In this embodiment, the bottom bracket is selected to be a U-shaped bracket 144. FIG. 1E shows Wing type top brackets 150 and 152 in a connector 100 configured without a transverse notch. In this embodiment, the bottom bracket in connector 100 is selected to be an L-shaped bracket 154. The brackets in FIG. 1E are shown with holes 4 for bolts or other fasteners that are to be used to retain the beams in the brackets.

(30) As shown in FIG. 2, the purpose of the inventive connector, an example of which is shown at 5, is to join straight beams 6, 7, 8 in a triangular union that forms one node, e.g., node 9B, of a multi-row polygonal arch structure. FIG. 2 illustrates that, at each node of a double row polygonal arch, two beams 6, 7 which are adjacent sides of a polygon meet end-to-end at an obtuse angle next to the midsection of a third beam 8. The beams that meet end-to-end 6, 7 at the node are in one row A of the arch and the third beam 8 is in the other row B of the arch. A series of these nodes 9ABC creates two polygonal arcs of straight beams which are staggered with respect to each other by one-half the length of a beam. Using the beam numbered 8 as an example, each beam in the structure belongs to three nodes: one node at each end of the beam 9A, 9C, and one node at its midpoint 9B.

(31) FIG. 3A gives a detailed view of one node created with a Wing type connector 300 showing the stringer beams 6, 7, 8 inserted into the two top brackets 1L and 1R, and the bottom bracket 2, respectively. A partial view of a transverse beam 10 is shown with one end inserted into the transverse notch between the ends of beams 6 and 7. FIG. 3B is a front view of one node of a double row polygonal arch showing the use of a triangular shim 11 to allow rectangular-ended beams to be inserted into the top brackets.

(32) Top Brackets: Each Y-shaped connector has two top brackets 1L, 1R, as illustrated in FIG. 4A. Each top bracket provides a joinery-free connection to a node of a double row polygonal arch for the end of a stringer beam.

(33) Any method of attaching the end of a stringer beam to a node of a double row polygonal arch that does not require joinery which interlocks or overlaps the beam with either the end of the stringer beam in the opposite top bracket or the transverse beam is considered a top bracket. All top brackets allow disassembly of the attachment between the stringer beam and the top bracket, and reuse of the bracket and beam.

(34) Each top bracket holds the stringer beam at a downward sloping angle relative to the upper transverse plane 43 of the connector (as seen in FIG. 1A). The slope of the top bracket establishes the shape of the arch at that node. The connector can be made with two top brackets that have different downward sloping angles to create non-circular arches.

(35) Each top bracket can have holes 4, as shown in FIG. 1E, and one or more flanges or other features for securing the stringer beam in each bracket in a Y-shaped connector according to the present invention. The geometry of the arch and the normal forces produced by the weight of the arch hold the stringer beams in the U-shaped and Fully-enclosed types of top brackets without fasteners. Fasteners can be added for convenience, safety or durability as required by the application.

(36) Transverse Notch: Referring to FIG. 4A, each connector may have a space between the top brackets termed the transverse notch 3. The transverse notch 3 can be used for various purposes including: adding a transverse beam to the node, suspending a load from the arch, housing a lifting device for dynamically controlling the curve of the arch, or attaching decorative elements to the nodes. The transverse notch is created by constructing the central structure 12 of the connector with the required space between the top brackets.

(37) Bottom Bracket: Each connector has one bottom bracket 2. The bottom bracket is constructed to attach the connector to the midsection of a stringer beam. In operation, bottom bracket applies an upward force on the stringer beam. The upward force is generated by the outward thrust produced by loads on the arch or by the weight of the cantilevered portion of the arch which is transferred to the connector through the top brackets and countered by the stringer beam in the bottom bracket.

(38) The bottom bracket may be configured as L-shaped, U-shaped, Fully-enclosed or simply as a flat plate of material extending down from the top brackets with one or more bolts used to attach the plate to the stringer beam.

(39) Central Structure: As shown in FIG. 4A, the central structure 12 is the part of the connector which joins the top brackets 1L and 1R to the bottom bracket 2.

(40) The central structure is a general term for the elements of the connector which are not included in the top brackets or bottom bracket. The central structure separates the top brackets to create the transverse notch 3 (when present), aligns the top and bottom brackets so the top brackets are centered on the same longitudinal plane 44 and are located on the opposite side of the vertical plane 45 of the connector from the bottom bracket, and contains braces 13 to make the connector more rigid when needed.

(41) FIG. 4B shows the rear view of the central structure. Bolts 14 or other suitable fasteners attach the bottom bracket to the central structure when the bottom bracket is a separate part. Likewise, bolts 15 or other suitable fasteners join the top brackets to the central structure when they are separate parts.

(42) As illustrated in FIG. 5A, the central structure can have vertical slots 16 or tracks which enable the vertical position 17 of the bottom bracket to be adjusted by sliding the bottom bracket up or down along the central structure 12 of the connector. FIGS. 5A, 5B, and 5C show the bottom bracket 2 moving from the end of the range of travel with the greatest separation from the top brackets up to the level of the least separation.

(43) FIG. 5D shows a typical implementation of the moveable bottom bracket using multiple bolts 14 to keep the bottom bracket aligned with the connector. A single slot can also be used.

(44) The sliding bottom bracket allows one connector to be used with beams of different lengths creating different spans for the arch.

(45) The central structure 12 with one or more slots or tracks can be constructed to extend up to the top of the top brackets or beyond, extending both above and below the top brackets. Sliding the bottom bracket from below to above hinged top brackets causes the arch to first collapse to a straight row of beams and then curve up rather than down.

(46) One or more embodiments of the invention may form the central structure part as part of the top or bottom brackets. In these embodiments, a portion of a top bracket or bottom bracket element performs the function of the central structure. FIG. 1E illustrates a central structure 12 that is an extension of the same piece of material as the bottom bracket,

(47) Top Bracket Mounting Using Hinges, Pivots or Flexible Material: The invention, as illustrated in FIG. 6, includes the optional attachment of top brackets to the central structure 12 with hinges 18, pivots or flexible material that have an axis of rotation that is perpendicular the vertical plane of the connector. Mounting the top brackets on hinges or pivots enables a connector to be used with a variety of beam lengths, thereby extending the range of applications in which it can be used. Hinge-mounted top brackets can be used in conjunction with the moveable bottom bracket shown in FIG. 5 or as an alternative. Top brackets can rotate through a range of angles 19. The range of angles includes, but is not limited to, the angles required to form a double row or multi-row polygonal arch.

(48) The pivot can be located anywhere along the top, bottom or transverse-notch-facing end of the top bracket. FIG. 6 illustrates a typical location for the hinge: the point at which transverse-notch-facing end of the top bracket meets the notch floor.

(49) Chaining Hook: One embodiment of the invention includes a chaining hook 20, as illustrated in FIG. 7A, which is an extension of the outer side wall of the bottom bracket 2 that folds outward away from the connector just above the level of the notch floor plate 21. As shown in FIG. 7B, the chaining hook fits into the transverse notch of an adjacent connector.

(50) In structures with two immediately adjacent double-row polygonal arches, the chaining hook 20 acts to counteract the torque that can develop at each node under load. Each Y-shaped connector tends to rotate toward the bottom bracket under load as outward thrust in the top bracket 1R is resisted by the bottom bracket. The chaining hook both stops that rotation for its own connector and counters the rotation in the adjacent connector with the force it applies. Braces 13 can increase the value of the chaining hook by making the central structure and bottom bracket 2 more rigid.

(51) The chaining hook can also fasten two adjacent double-row arches together by adding holes for fasteners to the chaining hooks 20 and notch floor plates 21.

(52) Building Blocks: The invention, as illustrated in FIG. 8, establishes a building block tor double row or multi-row polygonal arch structures. The building block consists of one connector 5 and one stringer beam 8 attached by the bottom bracket 2 of tile connector at the midsection of the beam. Two building blocks facing in opposite directions interlock when the building blocks are pushed together so that one end of the stringer beam of each block is fully inserted into a top bracket 1L, 1R of the other block. This interlocking feature enables the building of a double row polygonal arch from identical modules.

(53) FIG. 8 shows a building block made with a connector with L-shaped top brackets. This type of building block can be added to the arch by sliding it sideways onto other building blocks. L-shaped brackets preferably have holes 4 for fasteners to keep the beams in the bracket.

(54) Additionally, arches can be constructed using non-identical building blocks which are designed to interlock with just the adjacent blocks of the structure. Non-identical Building blocks can be asymmetrical to create parabolic and non-semi-circular arches. To create a parabolic or other non-circular arch, the length of the beams and the angles of the top brackets can be unique to every building block. Each building block may also be unique with respect to the location at which the bottom bracket is attached to the beam: exactly at the midpoint or offset from the midpoint toward one end of the beam.

(55) Referring to FIG. 9, the ends of the arch preferably connect to a foundation or abutment 22 using an abutment connection bracket. The abutment connection bracket has a hinged locking angle 23, a stub-beam 24 and, optionally, a cantilever support brace 25 fastened to a metal plate 26 which is bolted to the abutment 22. The locking angle 23 is the cantilever anchor during cantilevered construction and the bracket which transfers outward thrust from the arch to the abutment in a completed arch. The stub beam fits into the abutment-facing top bracket of the building block preventing lateral motion at the end of the arch.

(56) The stub beam 24 of the abutment connection bracket is a solid or tubular duplicate of the end of a stringer beam. The stub beam is welded or fastened to the abutment connection plate 26 at an angle matching the angle of the top bracket of the springer building block.

(57) The locking angle 23 is attached to the abutment connection plate 26 by a hinge 27 with the axis of rotation parallel to the ground. The hinge is mounted such that the lower wall 28 of the locking angle is flush with the abutment connection plate 26 at one end of the range of travel and at 90 degrees to the plate at the other end of the range of travel. The lower wall of the locking angle is as tall as the depth of the springer building block beam and at least as wide as the beam.

(58) The cantilever support brace 25 is located immediately below the locking angle and extends at 90 degrees from the abutment connection plate 26. The cantilever support brace 25 is only used when the arch is constructed by cantilevering. The cantilever support brace 25 supports the springer building block whose beam is the sole support for the entire cantilevered portion of one side of the arch during cantilevered construction.

(59) The cantilever support brace 25 has a notch 29 in the upper face of the brace to allow room for the bottom wall of the bottom bracket of the springer building block. The length of the cantilever support brace is application-specific. The cantilever support brace is welded or bolted to the metal plate. The cantilever support brace can be removed and reused once the keystone building block is in place.

(60) Referring to FIG. 10A, the springer building block 30 is attached to the abutment connection bracket 31 by sliding the top bracket 1R onto the stub beam 24. The locking angle 23 is held at the upper extent of the hinge's range of travel until the building block beam 32 in the bottom bracket touches the lower wall of the locking angle initiating the rotation of the locking angle.

(61) The abutment-facing end of the beam of each springer building block is shortened to fit the abutment connection bracket. The beam is cutoff at 90 degrees. The position of the cutoff is calculated so that the cutoff face of the beam end will rest squarely on the lower wall of the locking angle 28 when the stub beam 24 is fully inserted into the top bracket of the springer building block 30 and the arch is loaded. FIG. 10A shows the point at which the springer building block beam 32 first contacts the locking angle. FIG. 10B shows the locking angle 23 rotating as the stringer beam descends to the abutment connection plate 26 guided by the locking angle. FIG. 10C shows the final position of the springer building block 30 and the locking angle 23.

(62) The abutment connection bracket may have multiple stub beam and locking angle pairs so that multiple parallel arches to be connected to the abutment with one bracket.

(63) The invention enables a double-row polygonal arch to be assembled in its final location and vertical orientation from the abutments without any other scaffolding or support as illustrated in FIG. 11. FIG. 11 shows a structure consisting of four double-row polygonal arches: A through D, each arch at a different level of completion and all being built by the same method using cantilevering.

(64) Assembly Procedure: 1. Attach the abutment connection bracket 31 to the abutment 22 See Arch A. 2. Cut off one end of the beam of the springer building block 30 as specified in the abutment connection bracket description. 3. Attach a springer building block 30 to the abutment connection bracket 31, as shown in Arch A. 4. At the second and subsequent arches, optionally add a transverse beam to the transverse notches of adjacent connectors joining neighboring arches at the nodes as shown on the left side of Arches A through D. 5. Slide the abutmentfacing top bracket 35 of a standard building block 33 onto the end of the current highest building block in the half-arch, as shown in Arch B. 6. Repeat steps 4 and 5, alternating the direction in which the building blocks are facing, until half of the arch is complete, as shown in Arch C. 7. Repeat steps 1 through 5 from the other side of the span. 8. Slide the keystone building block 34 onto the voussoir building blocks 36 of each side of the span, as shown in Arch D. In arches with an even number of connectors, there are two connectors at the same level at the top of the arch. In these cases, the last building block added to the arch is considered the keystone building block. In cantilevered assembly, the keystone building block is added by sliding it into the arch from the side.

(65) Tied Beam Construction for Tied Arches: The connector supports creating a tied arch, as illustrated in FIG. 12, by connecting the springer building blocks 37 to opposite ends of a tie beam 39. An abutment connection bracket without the support brace is fastened to the end of the tie beam by a locally engineered solution. The springer building block connects to the abutment connection bracket as it would with an abutment-mounted bracket.

(66) Multi-rib Arch Structures: The invention enables multiple double-row polygonal arches to be connected into larger, multi-rib structures by transverse beams 10 inserted in the transverse notch 3 of the inventive connectors in each arch, as seen in FIG. 13. A primary feature of the invention is that the transverse beams at each node are located between the ends of the load-bearing stringer beams 6, 7, rather than above or below the beam-to-beam interface through which loads pass to the abutments. When an arch made with the invention is loaded, the transverse beams are held securely by the compression forces transmitted along each row of beams in the arch.

(67) Symmetrical Connectors: A variant of the double-row polygonal arch which has 3 rows of beams can be created by combining two standard connectors into one connector. Two combinations are possible: front-to-front and back-to-back. Front-to-front connectors, as shown in FIG. 14B, have a single common bottom bracket 2 and four top brackets 1L, 1R. Back-to-back connectors, as shown in FIG. 14A, have two top brackets 1L, 1R in common and two bottom brackets 2. Unlike the standard connectors which are the same at every node of an arch, the two types of 3-row connectors must alternate around the arch to produce polygonal rows of beams.

(68) The 3-row arch has value as a decorative structure. The 3-row arch can be used for structures if the beams in the center row are increased in size to be equal in load-bearing capacity of the two outer rows.

(69) Hinges and Pivots: The hinges and pivots described and illustrated represent generic, off-the-shelf components or application-specific engineered connections that have the axis of rotation indicated and perform the function described. The illustrations are not necessarily drawn to scale. Flexible material such as fabric can serve as a hinge in some applications. Custom engineered solutions and integration of the hinge function into elements of the connector are include as options where hinges or pivots are included in the invention.

(70) The various features associate with the examples described herein and shown in the accompanying drawings can be implemented in different examples and implementations without departing from the scope of the present disclosure. Therefore, although certain specific constructions and arrangements have been described and shown in the accompanying drawings, such embodiments are merely illustrative and not restrictive of the scope of the disclosure, since various other additions and modifications to, and deletions from, the described embodiments will be apparent to one of ordinary skill in the art. Thus, the scope of the disclosure is only determined by the literal language, and legal equivalents, of the claims which follow.