TECHNICAL FIELD
The present disclosure generally relates to a modular truss for building construction and a method for its assembly. More particularly, the present disclosure relates to an open-web steel joist having hollow chords and angled connecting brackets to provide a modular configuration and methods for assembling the open-web steel joist.
BACKGROUND
A structural truss is used to support a load, such as a bridge, building floor, or a roof. A truss is generally formed as a span of two primarily horizontal members called chords and an arrangement of vertical or angular members between the chords. The arrangement forms a web of triangular units positioned vertically that distributes weight from the load within the truss and accommodates tension and compression on the vertical or angular members. The truss, or a collection of trusses in parallel, transfers the load to supporting structures, such as to beams, other trusses, columns, pillars or walls, typically at ends of the span.
Open-web steel joists are a type of truss used, among other ways, to support roofs or floor decks in buildings having large open spaces, such as warehouses or stores. Steel has a high strength-to-weight ratio and provides an excellent material for components of a building truss. While discrete elements may be used for elements within the web of triangular units, in one form of open-web steel joist, often called a bar joist, a continuous steel bar having a zig-zag pattern forms the web of triangular units. Apexes of the zig-zag bar are welded to angled steel members that serve as the top and bottom chords.
For many reasons, bar joists have become a leading choice for trusses in constructing buildings with large spans. The high strength-to-weight ratio and relatively low price of steel leads to a lower price per pound for support structures formed by bar joists. Moreover, manufacturing of bar joists has become commoditized by a few large companies. These manufacturers centrally manufacture bar joists in a finished condition and have developed economies of scale that make bar joists cost effective for constructing a building. In addition, by arriving at a site ready to be installed, bar joists present an efficient choice for a building developer.
On the other hand, some circumstances can make the central manufacturing of open-web steel joists disadvantageous. For example, if interruptions at the central manufacturers arise or disruptions in the supply chain occur, the delivery of open-web steel joists from those few manufacturers can be impacted. Open-web steel joists are fundamental elements in large buildings, and delays in their delivery can negatively affect construction projects, often halting their development. Alternatives to the centralized manufacturing of open-web steel joists are typically expensive, labor-intensive, and not readily available.
Examples of the present disclosure are directed to overcoming deficiencies of the current system for manufacturing and supplying building trusses, such as open-web steel joists.
SUMMARY
In an aspect of the present disclosure, an open web steel truss includes a first hollow structural steel (HSS) member having a first top surface and a first bottom surface with first passageways vertically through the first HSS member and a second HSS member substantially parallel to the first HSS member. The second HSS member has a second top surface and a second bottom surface with second passageways vertically through the second HSS member. The truss includes a first group of angled brackets having first cap plates substantially perpendicular to first vertical flanges. The first vertical flanges are configured to be disposed within respective ones of the first passageways and to have first outer edges extending through the first bottom surface of the first HSS member. A second group of the angled brackets have second cap plates substantially perpendicular to second vertical flanges, where the second vertical flanges are configured to be disposed within respective ones of the second passageways and to have second outer edges extending through the second top surface of the second HSS member. In addition, the truss includes web members configured to extend between the first HSS member and the second HSS member. The web members have first ends and second ends, with individual ones of the first ends being configured to connect to individual ones of the first edges and individual ones of the second ends being configured to connect to individual ones of the second edges.
In another aspect of the present disclosure, a modular structural truss including a bottom chord arranged horizontally along a longitudinal axis and a hollow top chord arranged in a plane with the bottom chord. The hollow top chord has a top surface separated from a bottom surface by a gap, and the top surface includes a top slot aligned with a bottom slot in the bottom surface. The truss includes an angled bracket having a vertical flange and a cap plate connected at substantially a right angle. The vertical flange extends through the top slot and the bottom slot, and the cap plate contacts the top surface. At least one web member is positioned in the plane between the top chord and the bottom chord and has a top end and a bottom end. The top end of at least one web member is affixed to the vertical flange vertically below the bottom surface of the hollow top chord.
In yet another aspect of the present disclosure, a method for assembling a modular truss begins with arranging a top hollow structural member along a first longitudinal axis, where the top hollow structural member has at least one top channel formed transversely to the longitudinal axis and through the top hollow structural member. The method includes inserting a first flange of a top angled connection member into the at least one top channel, where the top angled connection member includes a top cap plate positioned substantially perpendicular to the first flange. A bottom hollow structural member is arranged along a second longitudinal axis and has at least one bottom channel formed transversely to the second longitudinal axis and through the bottom hollow structural member. The method includes inserting a second flange of a bottom angled connection member into the at least one bottom channel, where the bottom angled connection member includes a bottom cap plate positioned substantially perpendicular to the second flange. Finally, at least one web member is affixed to the first flange and to the second flange.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a front view of a modular open-web truss in accordance with an example of the present disclosure.
FIG. 2 is an exploded view of a partial joint between an angled bracket and a bottom chord of a modular open-web truss in accordance with an example of the present disclosure.
FIG. 3 is an exploded view of a partial joint between an angled bracket and a top chord of the modular open-web truss in FIG. 1 in accordance with an example of the present disclosure.
FIG. 4 is an isometric view of a middle joint in a bottom chord of the modular open-web truss in FIG. 1 in accordance with an example of the present disclosure.
FIG. 5 is a flowchart of a method for assembling a modular open-web truss in accordance with an example of the present disclosure.
FIG. 6 is an isometric transparent view of an enhanced modular truss in accordance with an example of the present disclosure.
FIG. 7 is an isometric view of a splice between sections of a bottom chord in the enhanced modular truss of FIG. 6 in accordance with an example of the present disclosure.
DETAILED DESCRIPTION
Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts. Multiple instances of like parts within a figure may be distinguished with a suffix, such as a letter and/or a number “-n.”
FIG. 1 illustrates a front view of a modular truss 100 within an XYZ coordinate system as one example consistent with the principles discussed in the present disclosure. In the example of FIG. 1, modular truss 100 includes a top chord 102 arranged longitudinally generally along the X axis and substantially parallel to bottom chord 104 also disposed generally along the X axis. Top chord 102 has a length in the X axis between a first end 103 and a second end 105 that defines a span for modular truss 100. Modular truss 100 is configured to support forces from a load acting generally along the +Z axis and/or the −Z axis and to distribute the forces to weight-bearing elements proximate to first end 103 and second end 105, such as pillars in a building.
In modular truss 100 of FIG. 1, top chord 102 is longer in the X axis than bottom chord 104. As a result, in the example of FIG. 1, modular truss 100 has an underslung design. In other examples not shown, top chord 102 and bottom chord 104 may have substantially equal lengths with modular truss 100 having parallel chords with square ends. In yet other possibilities not shown, top chord 102 and bottom chord 104 need not be parallel to each other, and modular truss 100 may take overall forms other than a parallel or flat truss as shown. For instance, consistent with the present disclosure, top chord 102 may be angled in the X-Z plane with respect to bottom chord 104, forming a pitched truss, or may even be curved. For simplicity, however, this disclosure is directed to a flat truss having parallel chords in an underslung design without restriction to extension of the disclosed principles to other truss configurations.
As depicted in FIG. 1, a series of vertical web members 106 are connected respectively between top chord 102 and bottom chord 104. A middle vertical web member 106-N is positioned vertically (i.e., substantially along the Z axis in FIG. 1) between top chord 102 and bottom chord 104 and horizontally through an approximate midpoint of top chord 102 between first end 103 and second end 105. Additional vertical web members, such as first vertical web member 106-1 and second vertical web member 106-2 are positioned in parallel to middle vertical web member 106-N at horizontal locations outwardly from the midpoint of top chord 102.
Pairs of vertical web members between top chord 102 and bottom chord 104 may each define panels within modular truss 100. For example, first vertical web member 106-1 and middle vertical web member 106-N define first panel 112-1, while second vertical web member 106-2 and middle vertical web member 106-N define second panel 112-2. For simplicity in discussion, modular truss 100 in FIG. 1 contains only two panels, but additional panels may be included to the left of first panel 112-1 and to the right of second panel 112-2 depending on the implementation for modular truss 100. Factors affecting the number of panels may include the length of the span between first end 103 and second end 105, the load to be borne by modular truss 100, the size and materials used for the members in modular truss 100, and other factors determinable by a person of ordinary skill in the art.
In addition, a series of diagonal web members 108 are also connected between top chord 102 and bottom chord 104. As shown, ends of each of the diagonal web members 108 are connected proximate to ends of one of the vertical web members 106, a location otherwise called a joint or a panel point, in a manner discussed further below. The diagonal web members 108 are arranged an angle relative to the vertical web members 106 in the X-Z plane. The precise angle may be determined from a depth of modular truss 100 (i.e., the vertical distance between top chord 102 and bottom chord 104) and a horizontal distance between the vertical web members 106. These distances will depend on the implementation and will be within the knowledge of those of ordinary skill in the art. Along with top chord 102 and bottom chord 104, vertical web members 106 and diagonal web members 108 form triangular sections within panels 112 and operate in tension and compression within modular truss 100 when loaded.
At the outer ends of modular truss 100, proximate to first end 103 and second end 105, triangular sections form end webs 114 from portions of top chord 102 and diagonal end members 110 for the underslung arrangement illustrated in FIG. 1. Specifically, at the left side of modular truss 100, a portion of top chord 102, a first diagonal end member 110-1, and first vertical web member 106-1 form a first end web 114-1. At the right side of modular truss 100, a portion of top chord 102, a second diagonal end member 110-2, and second vertical web member 106-2 form a second end web 114-2.
Turning back to the chords of modular truss 100, top chord 102 and bottom chord 104 in some examples are formed from hollow sections of structural steel having an upper surface, a lower surface, and an intermediate gap. For instance, top chord 102 and bottom chord 104 may be formed from tubular lengths of structural steel, such as hollow structural steel (HSS) sections that conform to either the ASTM Specification A500 or A1085, or materials of similar structural strength such as aluminum and associated alloys. As hollow sections, top chord 102 and bottom chord 104 may have any suitable cross-sectional shape, such as circular, rectangular, or square, as desired for the implementation.
While FIG. 1 shows a front view of an exemplary modular truss 100 overall, FIGS. 2-4 provide a closer look at various components and joints within the truss. FIG. 2 illustrates, in part, an exploded partial view of an exemplary bottom chord 104 viewed from the left side of modular truss 100 in FIG. 1. Bottom chord 104, in the example shown, is a HSS of rectangular cross-section. As such, bottom chord 104 has a top surface 202 and a bottom surface 204 separated by a gap 206. In the rectangular example of FIG. 2, bottom chord 104 includes a first side 208 and a second side 210 on opposite sides of gap 206. Accordingly, bottom chord 104 is a hollow steel structure with gap 206 being substantially empty between solid top surface 202 and bottom surface 204. In one example, bottom chord 104 has a width (along the Y axis in FIG. 2) of about 8 inches and a height (along the Z axis) of about 2 3/16 inches.
Returning to FIG. 1, consistent with the principles of the present disclosure, at least vertical web members 106, diagonal web members 108, and top chord 102 are connected to each other at respective joints or panel points by angled connection members, also referred to as brackets, which are further explained below. Brackets in modular truss 100 may have different sizes and configurations, particularly depending on the number of members being joined at a panel point. For example, at the joint along top chord 102 midway between first end 103 and second end 105, only a single web element, middle vertical web member 106-N, is adjoined at its upper end to top chord 102. As a result, the angled connection member at this central location may be sized accordingly and termed single bracket 120. In contrast, at the panel point at the lower end of middle vertical web member 106-N, three web elements are joined to bottom chord 104: middle vertical web member 106-N, first diagonal web member 108-1, and second diagonal web member 108-2. The angled connection member at this central location may be sized accordingly and termed triple bracket 122.
Other joints may contain angled connection members sized and configured to secure two web members to a chord, termed double brackets 124. For instance, at remaining panel points along top chord 102 in the example of FIG. 1 where upper ends of web members are connected, double brackets 124 designated with the suffix “A” may be used, such as first upper double bracket 124A-1 for joining first vertical web member 106-1 and first diagonal web member 108-1 with top chord 102. As well, second upper double bracket 124A-2 joins second vertical web member 106-2 and second diagonal web member 108-2 with top chord 102. Similarly, at panel points along bottom chord 104 where lower ends of web members are connected, double brackets 124 designated with the suffix “B” may be used, such as first lower double bracket 124B-1 for joining first vertical web member 106-1 and first diagonal end member 110-1 with bottom chord 104. Second lower double bracket 124B-2 joins second vertical web member 106-2 and second diagonal end member 110-2 with bottom chord 104. It will be understood that additional double brackets 124 may be used at other panel points along top chord 102 for longer spans of modular truss 100 having more panels 112.
Additionally, near first end 103 and second end 105 along top chord 102, end brackets 126 may be used to secure diagonal end members 110 associated with end webs 114. Specifically, first end bracket 126-1 may attach first diagonal end member 110-1 to top chord 102, and second end bracket 126-2 may attach second diagonal end member 110-2 to top chord 102. Attaching only one web member to a chord, end brackets 126 functionally resemble single bracket 120 in the example of FIG. 1 in an underslung design. However, end brackets 126 may have a larger size and strength than single bracket 120 due in part to the higher stresses and loads present near first end 103 and second end 105. Moreover, although not detailed in the figures, seat angles in the form of additional structural steel may also be used at and around first end bracket 126-1 and second end bracket 126-2 to assist with placing modular truss 100 on supporting members (not shown). The seat angles also help strengthen the tube members when necessary. Those skilled in the art will appreciate that the sizes and selections of angled connection members and the use of seat angles may be different than depicted for the example modular truss 100 of FIG. 1 based on, among other things, the implementation, loads, and configuration for the truss.
Referring again to FIG. 2, an exemplary angled connection member is illustrated, namely, first lower double bracket 124B-1 from the lower left of FIG. 1. While the design for the multiple angled connection members may vary within a truss, first lower double bracket 124B-1 may be representative of the general structure and shape of other angled connection members in modular truss 100, such as single bracket 120, triple bracket 122, double brackets 124, and end brackets 126. As with top chord 102 and bottom chord 104, the angled connection members represented by first lower double bracket 124B-1 in some examples are formed from a material having high strength and rigidity, particularly hot formed or cold rolled structural steel, although other materials having similar structural characteristics such as aluminum and aluminum alloys may suffice.
Consistent with the principles of the present disclosure, first lower double bracket 124B-1 generally is an angular arrangement of two planes of solid material, such as structural steel, formed in a T-shape. In one example, first lower double bracket 124B-1 includes a cap plate 220B-1 as a first plate of structural steel and a vertical flange 222B-1 as a second plate of structural steel, and the two plates are welded together substantially at a right angle along a seam 224B-1 where the two plates intersect. Although substantially a right angle provides a convenient and effective angle for cap plate 220B-1 and vertical flange 222B-1, other angles may also achieve desirable results. In addition, first lower double bracket 124B-1 and other angled structural members could be formed as an L-shape rather than a T-shape within the scope of this disclosure.
In one implementation, cap plate 220B-1 is 12 inches long (along the X axis in FIG. 2), 7 inches wide (along the Y axis), and 0.5 inches thick (along the Z axis), while vertical flange 222B-1 is 11 inches long (along the X axis), 8 inches high (along the Z axis) and 0.375 inches thick (along the Y axis). These dimensions are exemplary only. Vertical flange 222B-1 includes a first hole 226B-1 and a second hole 228B-1, which function to receive a connecting device (not shown) such as a bolt for holding a web element in place in a manner discussed in more detail below.
In another example, one or more angled connection members such as first lower double bracket 124B-1 may be formed as a “WT” from an I-beam of structural steel. In this approach, a section of I-beam may be obtained or cut at a length desired for the first lower double bracket 124B-1 along the X axis in FIG. 2 and then cut in half to form two T-shaped portions, commonly called WTs. Other approaches for constructing or forming a substantially T-shaped structure to serve as an angled connection member will be understood by those of ordinary skill in the art.
FIG. 2 is an exploded view of a partial joint 200 between first lower double bracket 124B-1 and bottom chord 104. First lower double bracket 124B-1 is oriented for assembly with bottom chord 104 with vertical flange 222B-1 facing upward along the +Z axis. In turn, bottom chord 104 includes two holes or openings in its vertical surfaces, namely a top slot 212 within top surface 202 and a bottom slot 214 within bottom surface 204. These slots may be cut or otherwise formed within bottom chord 104, such as with a plasma cutting machine, to be aligned vertically (i.e., along the Z axis in FIG. 2). Therefore, the aligned slots form a passageway or channel through bottom chord 104, typically across its center along the Y axis.
Top slot 212 and bottom slot 214 may have dimensions that substantially correspond with the thickness and length of vertical flange 222B-1. Thus, for the example of first lower double bracket 124B-1 discussed above, top slot 212 and bottom slot 214 may be openings of at least 11 inches long and 0.375 inches wide and typically a few hundredths of an inch larger than those dimensions. As their sizes and shapes substantially correspond, vertical flange 222B-1 may fit securely within bottom slot 214 and top slot 212, forming a slidable yet stable and snug connection between first lower double bracket 124B-1 and bottom chord 104.
When first lower double bracket 124B-1 and bottom chord 104 are mated together as a joint, an inner side 230B-1 of first lower double bracket 124B-1 contacts bottom surface 204 on bottom chord 104, and an outer side 232B-1 on first lower double bracket 124B-1 faces downwardly away from modular truss 100. First hole 226B-1 may receive connection hardware 130 (FIG. 1), such a bolt and nut, to secure first vertical web member 106-1 to first lower double bracket 124B-1. Second hole 228B-1 may receive similar connection hardware to secure first diagonal end member 110-1 to first lower double bracket 124B-1.
FIG. 3 is an exploded partial view of first upper panel point 300 from modular truss 100 of FIG. 1 where first vertical web member 106-1 and first diagonal web member 108-1 are joined to top chord 102. In FIG. 3, top chord 102 is shown truncated at its left side to reveal its hollow structure. In one example, top chord 102 is HSS having a width (along the Y axis in FIG. 3) of about 8 inches and a height (along the Z axis) of about 4 5/16 inches. First upper double bracket 124A-1 is mated with top chord 102 by vertical flange 222A-1 being positioned through a top slot 301 within a top surface 302 of top chord 102 and through a bottom slot 304 within bottom surface 306, passing through gap 308 of the hollow chord. Positioned upside down compared with first lower double bracket 124B-1 in FIG. 2, first upper double bracket 124A-1 in FIG. 3 has its outer side 232A-1 facing upwards and away from modular truss 100. When assembled, cap plate 220A-1 contacts and extends over a portion of top surface 302.
Vertical web members 106 and diagonal web members 108 may be made from a material having high strength and rigidity, particularly hot formed or cold rolled structural steel. FIG. 3 further shows that in some examples, vertical web members 106 and diagonal web members 108 may be L-shaped structural steel, such as L2 or L3 alloy tool steel. For some implementations, vertical web members 106 or diagonal web members 108 may be L-shaped angle steel having a 3×3 inch angle and a thickness of 0.25 inches. In other implementations, vertical web members 106 or diagonal web members 108 may be L-shaped angle steel having a 2.5×2 inch angle and a thickness of 3/16 inches. Other shapes, sizes, and materials such as aluminum and associated alloys are within the knowledge of those skilled in the art depending on the implementation.
Where first upper double bracket 124A-1 extends below top chord 102 (see FIG. 1), first vertical web member 106-1 and first diagonal web member 108-1 may be attached to vertical flange 222A-1. As with first lower double bracket 124B-1 in FIG. 2, the attachment may be provided using connection hardware such as bolts or similar components (not shown) passing through aligned holes in the web members in vertical flange 222A-1. In particular, first hole 310 and second hole 312 in vertical flange 222A-1 may be aligned respectively with third hole 314 in first diagonal web member 108-1 and fourth hole 316 in first vertical web member 106-1. Moreover, FIG. 3 illustrates that the web members may be attached on opposite sides of vertical flange 222A-1 (in the Y direction), which may provide improved stability and force distribution within modular truss 100. Specifically, first diagonal web member 108-1 is shown to be bolted to a front side of vertical flange 222A-1, while first vertical web member 106-1 is shown to be bolted to a back side of vertical flange 222A-1. It will be appreciated that the arrangement and sides of attachment for the web members and angle connection members is variable and within the discretion of those skilled in the art.
Similarly, FIG. 4 is an isometric view of middle lower panel point 400 from FIG. 1 for modular truss 100. Triple bracket 122 accommodates three web members: middle vertical web member 106-N, first diagonal web member 108-1, and second diagonal web member 108-2. Vertical flange 402 of triple bracket 122 extends upwardly in the +Z direction from bottom chord 104, passing through slots (not shown) within bottom surface 204 and top surface 202. Accordingly, cap plate 404 of triple bracket 122 extends across a portion of the bottom surface 204 of bottom chord 104. In one example for triple bracket 122, cap plate 404 is about 19 inches long (along the X axis), while vertical flange 402 is about 18 inches long and includes a first hole 406, a second hole 408, and a third hole 410 for attaching the three web members with connection hardware (not shown). As illustrated in FIG. 4, first diagonal web member 108-1 and second diagonal web member 108-2 may be attached on one side of triple bracket 122, with middle vertical web member 106-N being connected on an opposite side. Alternatively, all three web members could be attached on the same side of triple bracket 122. The arrangement of the connected components may depend on the implementation for modular truss 100.
As shown in FIGS. 1-4, angled connection members in the form of single bracket 120, triple bracket 122, double brackets 124, and end brackets 126 provide an interlocking structure between hollow top chord 102 and bottom chord 104 and their web members. By having vertical flanges resembling a blade, the connection members may be easily positioned with the vertical flanges passing through slots in top chord 102 and bottom chord 104 for stability. Cap plates help bind the connection members onto the chords as the web members are secured using connection hardware. To supplement the connection of web members to chords, the angled connection members may be welded to the chords and/or to the web members. For example, cap plate 404 in FIG. 4 may be welded around one or more of its edges to bottom surface 204 on bottom chord 104. Likewise, vertical flange 222A-1 in FIG. 3 may be welded at its intersection with bottom slot 304 on bottom surface 306 of top chord 102. Similarly, welding may occur between vertical flange 222A-1 and first vertical web member 106-1 and/or first diagonal web member 108-1, as desired.
The assembly results in a modular construction of common discrete parts suitable for easy installation into a strong and resilient structure. Connection hardware may hold the assembly in place and, if desired, welding can supplement the connection of the components into a unified modular truss 100. The cap plates on the various angled connection members in the assembled truss help transfer forces through direct bearing of metal to metal between the chords and the vertical flanges, and welding helps ensure a firm joint and passing of forces within modular truss 100. Moreover, when welded to a chord, the cap plates can help augment the strength of the chord over the slotted holes, particularly when welding occurs perpendicular to the span of the truss.
A method for assembling a modular truss may be defined by representative steps consistent with the present disclosure in the flowchart of FIG. 5. For the method of FIG. 5, the steps in which the method is described are not intended to be construed as a limitation. Any number of steps can be combined in any order to implement the disclosed method, can be performed in parallel to implement the processes, and in some embodiments, one or more blocks of the process can be omitted entirely. Moreover, the processes can be combined in whole or in part with other methods.
In FIG. 5, the method 500 begins with a step 502 of arranging a top hollow structural member along a first longitudinal axis. As indicated above, top chord 102 may in some examples be a top hollow structural member having a first longitudinal axis, as shown in FIG. 1, for example. In step 504, a first flange of a top angled connection member is inserted into at least one top channel formed transversely through the top hollow structural member. FIG. 3, for instance, shows first upper double bracket 124A-1 having vertical flange 222A-1 that slides into top slot 301 and bottom slot 304 transversely to the longitudinal axis of top chord 102.
Method 500 continues with a step 506 of arranging a bottom hollow structural member along a second longitudinal axis. Similar to top chord 102, bottom chord 104 in some examples may be a bottom hollow structural member having a second longitudinal axis, as shown in FIG. 1, for example. A step 508 includes inserting a second flange of a bottom angled connection member into at least one bottom channel formed transversely through the bottom hollow structural member. FIG. 2, for example, depicts this process. As illustrated, vertical flange 222B-1, as part of first lower double bracket 124B-1, is inserted into bottom slot 214 and top slot 212 of bottom chord 104, which form a channel transverse to the longitudinal axis of the hollow structural member.
Finally, method 500 includes a step 510 of affixing at least one web member to the first flange and to the second flange. As shown in FIG. 4, for example, triple bracket 122 has vertical flange 402 that includes first hole 406, second hole 408, and third hole 410, which are aligned with corresponding holes in second diagonal web member 108-2, middle vertical web member 106-N, and first vertical web member 106-1 for affixing the components together. Similarly, FIG. 3 illustrates that first diagonal web member 108-1 and first vertical web member 106-1 may be affixed to vertical flange 222A-1 following the alignment of first hole 310 with third hole 314 and second hole 312 with fourth hole 316. Additional method steps of securing the components of the truss through welding and installing the truss onto load-bearing elements will be apparent from the other discussion within this disclosure.
FIG. 6 depicts an enhanced modular truss 600 based on the same architecture as modular truss 100 in FIG. 1. Enhanced modular truss 600 has a longer span than modular truss 100. Although the middle and right half of enhanced modular truss 600 is truncated in FIG. 6 for purposes of illustration, enhanced modular truss 600 includes ten panels, four of which are shown. As with modular truss 100, angled connection members connect web members to a hollow top chord, such as fifth upper double bracket 624A-5, seventh upper double bracket 624A-7, and ninth upper double bracket 624A-9 within outer top chord 602. Similar to the discussion above for FIGS. 1-4, the vertical flanges on the angled connection members pass through outer top chord 602 from which vertical and angular web members are bolted. Cap plates of the angled connection members may be welded to the upper surface of outer top chord 602.
Angled connection members also pass through slots within outer bottom chord 604 and provide connection points for vertical web members. Thus, joints exist for fifth vertical web member 606-5 and seventh diagonal web member 608-7, seventh vertical web member 606-7 and ninth diagonal web member 608-9, and ninth vertical web member 606-9 and first diagonal end member 610-1. Cap plates of these angled connection members, namely, fifth lower double bracket 624B-5, seventh lower double bracket 624B-7, and ninth lower double bracket 624B-9, may be welded to the lower surface of outer bottom chord 604.
Due to its increased span and load, enhanced modular truss 600 may include reinforced web members. For example, first diagonal end member 610-1 and ninth vertical web member 606-9 could include two L-shaped beams sandwiched together for increased structural strength. Alternatively, thicker structures for ninth vertical web member 606-9 or first diagonal end member 610-1 or a composition having higher strength than other web members could be selected.
As enhanced modular truss 600 has an extended length, the top chord and bottom chord may include more than one structural section spliced together longitudinally. For instance, in FIG. 6, a top chord across the entire span of enhanced modular truss 600 may include at least inner top chord 601 and outer top chord 602 sealed together at a top chord splice 640. Top chord splice 640 may be accomplished by any means known to those skilled in the art. One example for top chord splice 640 may include metal plates welded to the abutting ends of inner top chord 601 and outer top chord 602, which are bolted or otherwise connected securely together. Alternatively, the abutting ends of inner top chord 601 and outer top chord 602 could be welded directly to each other. Although not shown in FIG. 6, an additional top chord splice may be used for one or more other segments of the top chord at a right side of enhanced modular truss 600 to provide additional length for the span.
Similarly, the bottom chord in enhanced modular truss 600 may include a bottom chord splice 642 for joining inner bottom chord 603 and outer bottom chord 604 as another option. FIG. 7 shows a closer view of bottom chord splice 642 isolated within a fractional portion of outer bottom chord 604. Inner bottom chord 603 and outer bottom chord 604 are positioned to abut at end-to-end joint 702. Two L-shaped or right-angle braces, identified as first edge brace 704 and second edge brace 706, are adhered about end-to-end joint 702 to provide lateral enforcement. In particular, first edge brace 704 is positioned with one flange on top walls of inner bottom chord 603 and outer bottom chord 604 and a second flange on side walls of inner bottom chord 603 and outer bottom chord 604. As well, second edge brace 706 is positioned with one flange facing bottom walls of inner bottom chord 603 and outer bottom chord 604 and another flange facing opposite side walls of inner bottom chord 603 and outer bottom chord 604, as shown in FIG. 7. The combined construction is held in place by welding. Bottom chord splice 642 may provide more rigidity and enforcement to end-to-end joint 702 than top chord splice 640 or a direct end-to-end weld with respect to lateral forces in the Z direction for an enhanced modular truss 600 having an extended length.
Referring back to FIG. 6, hanging bracket 644 provides an additional feature for either modular truss 100 or enhanced modular truss 600. As an angled connection member, hanging bracket 644 substantially has a T-shape and may be structurally equivalent to any one of the existing angled connection members, i.e., single bracket 120, triple bracket 122, double brackets 124, and end brackets 126. In some examples, hanging bracket 644 is equivalent to single bracket 120 and has a single hole within its vertical flange. As shown in FIG. 6, hanging bracket 644 is positioned upside down compared with outer brackets in outer bottom chord 604. The vertical flange of hanging bracket 644 may pass through an additional channel formed by top and bottom slots (not shown) within bottom chord 604 to provide a means for attaching a concentrated load, such as a lighting fixture, HVAC equipment, or ducting. The arrangement of a T-shaped bracket having a cap plate that may be secured through a channel within hollow outer bottom chord 604 enables the installation of customizable attachment points within enhanced modular truss 600 or modular truss 100 depending on the need.
In short, the present disclosure provides a modular structural truss having an open-web configuration and a method for its assembly based on a substantially parallel arrangement of a top hollow chord and a bottom hollow chord. The hollow chords have slotted channels formed vertically therethrough. Vertical flanges on T-shaped brackets are positioned within the slotted channels, while orthogonal cap plates on the brackets abut an upper surface of the top hollow chord and a lower surface of the bottom hollow chord. Web members extending between the two chords are affixed to respective ends of the vertical flanges that pass through the chords, and the cap plates may be welded to the chords. The modular truss enables flexibility in design and on-site assembly using common components to achieve high load tolerance.
Particularly with cap plates of the T-shaped brackets welded to the top hollow chord and the bottom hollow chord, the modular structural truss exhibits weight bearing characteristics equal to or exceeding conventional bar joists of similar size. Moreover, with respect to uplift strength, such as may be faced in high winds perhaps from tropical storms or hurricanes, the modular structural truss of this disclosure has a higher load capacity than comparable bar joists, making it particularly suitable for construction in coastal areas.
Similarly, the T-shaped structure of the angled brackets can help provide safety redundancy for the described modular truss. For example, if welds applied between a cap plate, such as cap plate 220A-1 in modular truss 100, and top chord 102 were to fail or be deficient, the abutment of cap plate 220A-1 to top surface 302 on top chord 102 will remain. This abutment will ensure continued connection between top chord 102 and web members attached to first upper double bracket 124A-1 (i.e., first vertical web member 106-1 and first diagonal web member 108-1). In contrast, welding failures in a gusset on conventional joists and trusses can cause a loss of connection between a web element and a top chord.
The modular structural truss of the present disclosure also enables flexible manufacture, delivery, and assembly not typically available for the construction industry. The small number of parts for the truss can be chosen from commodity items: lengths of HSS for hollow chords, lengths of L-shaped steel for web members, plates of structural steel or I-beams or WTs from I-beams for angled connection members, and connection hardware. Indeed, the modular structural truss could be provided and constructed using only those components. Minimal labor is involved: precision cutting of slotted channels through the chords, welding of plates to form angled connection members, bolting of parts together, and welding of parts together. As a result, the limited components of the flexible truss can be shipped or acquired as discrete parts, if desired, and assembled on site. Accordingly, this modular structural truss can avoid challenges that may arise from the centralized manufacture and shipment of open-web steel joists and similar products, e.g., supply-chain bottlenecks or labor disruptions. Further, the modular truss enables access to a fundamental building component for portions of the construction industry lacking leverage with large, centralized manufacturers.
Unless explicitly excluded, the use of the singular to describe a component, structure, or operation does not exclude the use of plural such components, structures, or operations or their equivalents. As used herein, the word “or” refers to any possible permutation of a set of items. For example, the phrase “A, B, or C” refers to at least one of A, B, C, or any combination thereof, such as any of: A; B; C; A and B; A and C; B and C; A, B, and C; or multiple of any item such as A and A; B, B, and C; A, A, B, C, and C; etc.
Terms of approximation are meant to include ranges of values that do not change the function or result of the disclosed structure or process. For instance, the term “about” generally refers to a range of numeric values that one of skill in the art would consider equivalent to the recited numeric value or having the same function or result. Similarly, the antecedent “substantially” means largely, but not wholly, the same form, manner or degree, and the particular element will have a range of configurations as a person of ordinary skill in the art would consider as having the same function or result. As an example, “substantially parallel” need not be exactly 180 degrees but may also encompass slight variations of a few degrees based on the context.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
Patent Application
20230323665
