Patent Publication Number: US-2022213684-A1

Title: Modular composite action panel and structural systems using same

Description:
BACKGROUND 
     The present disclosure generally relates to the construction of structural systems. More specifically, the disclosure relates to construction of floor, ceiling, and wall systems. 
     Structural floors are one of the main components of building structural systems. They carry loads (such as occupants, furniture, and equipment) to structural beams and columns, which in turn transfer the loads to the foundation. Conventional modern structural floors are typically constructed from concrete due to its versatility in creating different shapes of floor plates, its ability to span long distances when acting in composite with steel reinforcement, and its resistance to vibrations and sound transfer. Timber floors are also used, typically with a concrete topping slab. However, in most jurisdictions timber floors are currently not permitted in high-rise buildings with 6 or more stories above ground level without extensive limitations due to concerns that fire would significantly reduce their load carrying capacity. 
     During construction of concrete floors, wet concrete needs to be supported by a form until the concrete is set. Commonly used forms for structural floors include: leave-in-place corrugated metal deck forms, typically used in steel buildings; temporary plywood formwork supported on closely spaced shoring, typically used in concrete buildings; and precast concrete panels that act in composite with the cast-in-place topping slab during building service, typically used in precast concrete buildings. The metal deck forms are commonly used to span approximately 10′ without shoring, but at longer spans the depth of corrugation required to stiffen the form results in excessive floor thickness and higher cost. Trussed deck is commonly used in Asian markets in lieu of corrugated metal deck in steel buildings: a rebar lattice truss is used to stiffen the flat metal. Trussed deck is typically limited to the same span range as corrugated metal deck. The temporary plywood formwork also has drawbacks: shoring for the plywood formwork interferes with construction activities on the floors below, the time required for shoring and formwork to remain in place impedes construction schedule, and the plywood forms are typically discarded after removal, creating negative environmental impact. The precast concrete panels typically require temporary shoring for longer spans. 
     The Filigree Wideslab System (Mid-State Filigree Systems, Inc. 1992) consists of reinforced precast floor panels that serve as permanent formwork, with a steel lattice truss projecting from the top of the precast unit to stiffen the panel (refer to product document). However, similar to other precast concrete panel forms, they are heavy to transport and lift into place. 
     In addition, most occupied spaces use an additional ceiling finish such as dry wall or timber below the structural slab, particularly metal decks. This incurs additional material and labor cost, as well as increased environmental impact. 
     SUMMARY 
     Disclosed herein are one or more inventions relating to a prefabricated modular composite action panel, structural systems employing the composite action panel, methods of fabricating the composite action panel, and methods of erecting structural systems employing the composite action panel. 
     The disclosed composite action panel can provide a lightweight formwork that can achieve long spans without shoring, and at the same time remain in place as an attractive permanent ceiling finish. Even more efficiency can be achieved if the formwork can act in composite with concrete as part of a structural system. To that end, lightweight timber panels with stiffening elements fabricated from conventional concrete reinforcements can serve this purpose. 
     As used herein: 
     “Timber” includes natural and manmade wood unless stated otherwise. “Timber” and “lumber” are used interchangeably herein.
 
“Timber panel” means a layer of timber whether comprised of one sheet or multiple sheets of timber and whether a given sheet of timber is single or multi-ply.
 
“Composite action panel” means a panel embodying principles disclosed herein. It may also be referred to as a timber-rebar truss panel, a lumber-rebar truss panel, or a prefabricated modular panel.
 
“Galloping” means a serpentine profile in reference to the bent shape of a steel rod or bar, including a sinusoidal characteristic.
 
“Prefabricated” means built in advance and transportable to an installation site for installation at the installation site.
 
     In an embodiment, a composite action panel comprises: 
     steel stiffening elements aligned parallel to each other and each extending along a span direction; and
 
a timber panel secured to the steel stiffening members via structural connectors,
 
wherein,
         the steel stiffening members function as a first chord and a web element of the composition action panel and the timber panel functions as a second chord of the composite action panel, and   the steel stiffening members and the timber panel achieve composite action and truss behavior.       

     In an embodiment, the structural connectors are positioned at discrete locations along the steel stiffening members. 
     In an embodiment, the structural connectors secure the steel stiffening elements and the timber panel continuously along the span direction. 
     In an embodiment, the steel stiffening members and the timber panel are connected together by means of connector structures comprising metal plates to which the steel stiffening elements are welded or bolted, and fastener elements selected from the group consisting of mechanical fasteners, nails, spiked plates, and adhesive. 
     In an embodiment, the timber panel is selected from the group consisting of cross-laminated timber (CLT), nail-laminated timber (NLT), dowel-laminated timber (DLT), and glue-laminated timber (GLT). 
     In an embodiment, the steel stiffening element are either three-dimensional or planar rebar trusses. 
     In an embodiment, each steel stiffening member comprises a three-dimensional rebar truss comprising (a) a deformed rebar as the top chord, two continuous bars bent to form two web diagonals and secured to the deformed rebar, and two bottom bars, each attached to a respective base of the web diagonals, the web diagonal bars being bent in a galloping fashion. [001(1] In an embodiment, each steel stiffening member comprises a planar truss comprising (a) a top bar, (b) one continuous web diagonal bent in a galloping fashion, and (c) one bottom bar attached to the base of the web diagonal. 
     In an embodiment, the steel stiffening elements comprise perforated metal plates or prefabricated steel shapes. 
     In an embodiment disclosed herein, the composite action panel is prefabricated. 
     In an embodiment, the steel stiffening elements extend in both the span direction and another direction traversing the span direction. 
     In an embodiment, a structural element, comprises: 
     a composite action panel according to any of the prior embodiments; and
 
concrete or cementitious material in which the steel stiffening elements are embedded.
 
     In an embodiment, the structural element is part of a roof system, a floor system, a wall, a column, a brace, or a beam. 
     In an embodiment, the structural element is part of a roof system or a floor system. 
     In an embodiment a composite monolithic system, comprises: 
     a plurality of composite action panels according to any of the embodiment above;
 
splice reinforcements between adjoining composite action panels; and
 
concrete or cementitious material embedding the steel stiffening elements.
 
     In an embodiment, the composite monolithic system is a floor system or a roof system. 
     In an embodiment, the composite monolithic system further comprises a support framework supporting the floor system or the roof system, the support framework being selected from the group consisting of steel beams, precast concrete beams, a cast-in place concrete beams, or timber beams. 
     In an embodiment of a composite monolithic system the composite panels are either simple spans between the supporting framework or continue across a top of the supporting framework with openings for the concrete slab to achieve composite action with the support framework. 
     In an embodiment of a monolithic structural system, the timber panel can be designed to contribute to the strength and/or serviceability of the structural floor in the permanent condition, with the timber panel and concrete thicknesses selected based on desired participation from the timber panel, and additional shear connectors added for desired level of composite action. 
     In an embodiment, a method comprises: 
     prefabricating a composite action panel according to any of the prior embodiments;
 
transporting the composite action panel to an installation site;
 
supporting the composite action panel in a desired orientation; and
 
embedding the steel reinforcement elements in a concrete slab.
 
     As can be appreciated, the timber panels act in composite with the steel stiffening elements to support wet weight of concrete in the temporary condition, and can be designed to span with minimal or no shoring up to typical spans of one-way or two-way reinforced concrete slabs. In the permanent condition, the steel stiffening element can be used to reinforce the concrete slab, and the timber panel can act in composite with the concrete slab to meet strength and serviceability requirements. The underside of the timber panel preferably is protected with a protective layer during construction, and can serve as a visually pleasing ceiling finish in the permanent condition. The prefabricated formwork preferably is prepared in advance, reducing site labor and increasing construction speed. The significant reduction of shoring allows construction activity to take place on the levels below, further reducing construction schedule. By assembling multiple prefabricated composite action panels in a modular array, a floor system can be created which is adaptable to any building geometry. The prefabricated composite action panels are lightweight and stackable, facilitating transportation and erection. The leave-in timber ceiling finish eliminates the need for additional ceiling material, reducing overall environmental impact. The system is versatile and can be used with steel framing, concrete cast-in place beams and columns, precast concrete systems, and timber framing. 
     Other systems, methods, features, and advantages of the one or more disclosed inventions will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the invention(s), and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of the system disclosed herein, together with the description, explain the advantages and principles of the disclosed system. In the drawings: 
         FIG. 1  is a perspective view of an illustrative example of a single composite action panel that can be used as a composite timber floor system panel after the placement (pouring) of concrete or cementitious material which is consistent with principles disclosed herein. 
         FIG. 2  is a perspective view of an illustrative example of a single composite action panel prior to the placement of concrete which is consistent with principles disclosed herein. 
         FIG. 3  is an exploded view of an exemplary composite action panel or timber-rebar truss panel depicting individual components of the timber-rebar truss panel shown in  FIG. 2  prior to assembly of the timber-rebar truss panel shown in  FIG. 2 . 
         FIG. 4 a    is a perspective view of an exemplary rebar truss assembly depicting the components of a single rebar truss assembly that may be employed as a steel stiffening element of the single timber-rebar truss panel shown in  FIG. 3 . 
         FIG. 4 b    is an exploded view of the exemplary rebar truss assembly shown in  FIG. 4   a.    
         FIG. 5 a    is a plan view of the prefabricated rebar truss illustrated in  FIG. 4   a.    
         FIG. 5 b    is an elevation view of the prefabricated rebar truss illustrated in  FIG. 4 a   . Refer to  FIG. 5 a    for location of section  5   b.    
         FIG. 6 a    is a section view cut at a typical cross section of the prefabricated rebar truss illustrated in  FIG. 4 a   . Refer to  FIG. 5 b    for location of section. 
         FIG. 6 b    is a section view cut at the end of the prefabricated rebar truss illustrated in  FIG. 4 a   . Refer to  FIG. 5 b    for location of section. 
         FIG. 6 c    is a section view cut at the end looking perpendicular to the span direction of the prefabricated rebar truss illustrated in  FIG. 4 a   . Refer to  FIG. 5 a    for location of section. 
         FIG. 7  is a plan view of the illustrative single composite action panel shown in  FIG. 2  which illustrates the layout of the prefabricated rebar truss and the transverse reinforcement shown in  FIG. 3 . 
         FIG. 8 a    &amp;  FIG. 8 b    are longitudinal and transverse elevation views of the composite action panel assembly shown in  FIG. 7  taken along lines  8   a - 8   a ′ and  8   b - 8   b ′, respectively. 
         FIG. 9  is a plan view showing the connectors laid out on the timber panel  10  as shown in the illustrative single composite timber floor system panel shown in  FIG. 2 . 
         FIG. 10 a    is a plan detail of a corner of the timber panel and connector plate assembly as shown in section  10   a  in  FIG. 9   
         FIG. 10 b    is a plan detail of a side edge of the timber panel and connector plate assembly as shown in section  10   b  in  FIG. 9   
         FIG. 11 a    is a section detail cut at the end of the illustrative composite action panel shown in  FIG. 2  which is consistent with the current disclosure, as shown by section  11   a  in  FIG. 9   
         FIGS. 11 b    &amp;  11   c  are additional section details cut through the composite action panel shown in  FIG. 2 , as shown by sections  11   b  and  11   c , respectively, in  FIG. 9 . 
         FIGS. 12 a - f    depict sections of alternative connection types that can be used to make a positive connection between the timber panel and rebar truss cage components depicted in  FIG. 3 . Any of these connection types may be used in combination with any of the other connection types to form a positive connection between the timber panel and rebar truss cage. 
         FIG. 13 a    is a perspective view of an illustrative structural system using structural steel for the beam (end  42  a side  43 ) and column  41  framing, and a series of the prefabricated modular composite action panels  50  (refer to  FIG. 2 ) to construct a floor system. 
         FIG. 13 b    is a plan view of the illustrative structural system shown in  FIG. 13  showing the modular nature of the disclosed composite action panels when employed on structural steel framing. 
         FIG. 14  is a section depicting the side connection detail between two adjacent composite action panels of the modular system as shown by section  14  in  FIG. 13 b   . This section depicts the mechanism that is installed between composite action panels to prevent bleeding of concrete during the construction process. 
         FIG. 15 a    is a section detail showing an end support detail of a prefabricated modular composite action panel supported by a steel wide flange beam at an interior support condition, as shown by section  15   a  in  FIG. 13   b.    
         FIGS. 15 b    &amp;  15   c  are section details of alternate details of a prefabricated modular composite action panel supported by a steel wide flange beam at an interior support condition.  FIG. 15 b    shows a configuration in which the timber portion of the prefabricated composite action panel is installed below the top of steel elevation thereby reducing overall structural depth.  FIG. 15 c    is a detail showing the composite action panel running continuously over the interior steel support beam. Refer to  FIG. 13 b    for location of interior support conditions in a multi-composite action panel modular layout. 
         FIG. 16 a    is a section detail showing an end support detail of a prefabricated modular composite action panel supported by a steel wide flange beam at an edge support condition as shown in section  16   a  in  FIG. 13   b.    
         FIG. 16 b    is an alternative section detail showing an end support detail of a prefabricated modular composite action panel supported by a steel wide flange beam at an edge support condition. Refer to  FIG. 13 b    section  16   a  for location of section. Similar to the alternative shown in  FIG. 15 b   , this alternative configuration is such that the timber portion of the prefabricated composite action panel is installed below the top of steel elevation thereby reducing overall structural depth. 
         FIG. 17 a    is a section detail showing an end support detail of a prefabricated modular composite action panel supported by a cast-in-place concrete beam at an interior support condition. Refer to section cut  15   a  in  FIG. 13 b    for section cut locations. 
         FIG. 17 b    is a section detail showing an end support detail of a prefabricated modular composite action panel supported by a cast-in-place concrete beam at an edge support condition. Refer to section cut  16   a  in  FIG. 13 b    for section cut locations. 
         FIG. 18  is a perspective view of a potential hoisting configuration of a single prefabricated modular composite action panel. 
         FIG. 19 a    is a general flow chart outlining the primary steps and materials involved in the fabrication and erection of a modular composite timber floor system consistent with principles disclosed herein. 
         FIG. 19 b    is a flow chart outlining the fabrication process of a single prefabricated modular composite action panel consistent with principles disclosed herein. 
         FIG. 19 c    is a flow chart outlining the erection process of a structural floor system using one or more prefabricated composite action panels consistent with principles disclosed herein. 
         FIG. 20  is a perspective view showing a single bay of an exemplary structural system and identifies the primary element types used in a typical structural system. 
         FIG. 21 a    is a perspective view illustrating the primary components of a prefabricated modular timber beam element. 
         FIG. 21 b    is a perspective view illustrating the primary components of a prefabricated modular timber column element. 
         FIG. 21 c    is a perspective view illustrating the primary components of a prefabricated modular timber wall element. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to one or more implementations in accordance with a prefabricated modular composite action panel consistent with the principles disclosed herein as illustrated in the accompanying drawings. The prefabricated modular composite action panel, may be incorporated into a floor or roof system of a building or other structure and used to resist area loads as well as to provide a continuous diaphragm at each level of application. The modular nature of the composite action panel allows flexibility such that a system utilizing the composite action panel may be tailored to fit any building geometry with a series of repetitive composite action panel elements preferably connected as illustrated in the accompanying drawings and description. The prefabricated nature of the composite action panel allows composite action panels to be shop fabricated, improving construction tolerances, and increasing speed of construction while eliminating the need for separate tradesmen to field install slab reinforcement. 
     Exemplary embodiments of the composite action panel of this disclosure and systems employing same are illustrated in the accompanying drawings and description. However, the composite action panel may be implemented such that any combination of the primary materials (timber, steel and concrete) presented herein may be utilized at any point during the lifespan of a structural system to achieve a structural floor or roof system, other systems as disclosed herein. A modular composite timber floor system consistent with principles disclosed herein enables the reduction or elimination of temporary formwork and shoring while utilizing traditional building materials to increase speed of construction and reduce overall building costs. Additional benefits of the proposed disclosure include but are not limited to: lightweight and stackable making for easy transportation and erection, introduces sequestered carbon into the project thus improving sustainable performance, and provides an attractive visual finish potentially eliminating the need for a hung ceiling. 
       FIG. 1  is a perspective view of an illustrative example of a single composite timber floor system employing one or more composite action panels consistent with principles disclosed herein. As seen in  FIG. 1  the modular composite timber floor system panel includes a timber panel  10  connected to steel reinforcement  20  via connectors  30  which form a composite action panel. Concrete  40  (shown in phantom for easier understanding) is cast on top of the composite action panel(s), encasing and embedding all of the steel reinforcement. In this exemplary description, the timber panel  10 , rebar trusses  20  and connectors  30  are prefabricated and combined into one or more composite action panels and shipped to site. Once installed the one or more composite action panels are installed on site, and then the concrete  40  is cast in place creating a monolithic floor system.  FIG. 2  illustrates this prefabricated composite action panel prior to placement of concrete  40 . 
     The timber panel  10  illustrated in  FIG. 1  shows an exemplary size and shape of timber panel, however it is possible to implement panels of any shape and size in accordance with principles of the present disclosure. Although the timber panel  10 , illustrated in  FIG. 1 , shows a cross laminated timber profile with 3 ply thickness, any number of ply&#39;s may be used. The timber panel must be sufficiently strong to act as part of a composite concrete form. Alternate means of lamination are also possible including, but are not limited to, dowel laminated timber, nail laminated timber &amp; glue laminated timber panels. In addition, as noted above, the timber can be made of natural or man-made wood. 
     In this illustrative example, the steel reinforcement  20  is composed of deformed steel bars and round steel rods. However, alternative types of steel reinforcement can be used to achieve composite action between the other materials (timber  10  &amp; concrete  40 ). These alternative types include but are not limited to steel plates, perforated steel plates and rolled steel sections. Further this illustrative example shows an exemplary size and configuration of steel reinforcement, however steel reinforcement  40  can be configured in a variety of ways to achieve the required strength and serviceability performance. 
       FIG. 3  is an exploded perspective view of the illustrative example shown in  FIG. 2 .  FIG. 3  shows the timber panel  10  at the base of the illustrative assembly or composite action panel. Connectors  30  allow for a structural connection between the timber panel  10  and the prefabricated rebar trusses  21 . In this illustrative example, the connector plate  30  is connected to the timber panel  10  via self-tapping lag screws  32 , as shown in  FIG. 11 a -11 c   . This is just one potential method of connection between the timber panel  10  and the connectors  30 . Alternate connection techniques will be described in more detail in the following discussion (refer to  FIGS. 12 a -12 f   ). The rebar trusses  21  are welded to the connectors  30  at all points of contract. In this illustrative example, the composite action panel is designed and detailed as a 1-way system, meaning the composite action panel spans in the span direction or length of the rebar trusses (long direction in the figure) and is supported at both of its ends in the cross-span or transverse direction (the short ends in the figure). The rebar trusses  21  are configured to run parallel to this span direction. By connecting a series of rebar trusses  21  in parallel via the connectors  30  to the timber panel  10 , a prefabricated composite action panel is created. Transverse reinforcement  22  is provided in the direction perpendicular to the span. In this illustrative example, transverse reinforcement  22  is provided as additional reinforcement bars which are wire tired in place using standard construction techniques, however it is possible that the transverse reinforcement bars  22  are integrated into the rebar trusses  21  to contribute to the composite action panel&#39;s composite strength and allow for 2-way system applications. 
       FIG. 4 a    is a perspective view of a single rebar truss  21  illustrated in  FIG. 3  and described above. The rebar truss  21  is a 3-dimensional truss that is made up of one straight continuous top deformed bar  21 A, two inclined continuous diagonal bars  21 B which are bent in a galloping fashion, two straight continuous bottom deformed bars  21 C, two horizontal end support bars  21 D (one at each end) and two vertical end support bars  21 E (one at each end). All bars are welded together at points of contact to create a single three-dimensional rebar truss  21 . 
       FIG. 4 b    is a perspective view of an explosion diagram of the components described above in  FIG. 4 a   . The inclined continuous diagonal bars  21 B are welded to the top bar  21 A and bottom bat  21 C. Bottom bars  21 C are welded to the horizontal end support bars  21 D which are welded to the vertical end support bars  21 E. The vertical end support bars  21 E are also welded to the top bar  21 A. As previously noted, this represents but one preferred rebar truss configuration. Other configurations may be implemented consistent with the principles of the present disclosure. 
       FIG. 5 a    is a plan view of the prefabricated rebar truss  21  illustrated in  FIG. 4 a   . Sections  5   b  &amp;  6   c  are used as reference for the sections shown in  FIGS. 5 b    &amp;  6   c.    
       FIG. 5 b    is an elevation view of the prefabricated rebar truss  21  illustrated in  FIG. 4 a   . Refer to  FIG. 5 a    for location of the section  5   a . This elevation shows an example of galloping configuration of the inclined diagonal bar  21 B. As shown, the galloping diagonal bar  21 B has horizontal segments which occur at regular spacing at both the top and bottom of the truss allowing sufficient contact between the diagonal bar  21 B and the top and bottom bars  21 A and  21 C respectively. The horizontal segments of the diagonal bar  21 B are shown in this preferred embodiment, but are not required as long as sufficient contact between the diagonal bars  21 B and top and bottom bars ( 21 A &amp;  21 C) is achieved. This truss profile is created from a continuous piece of round steel rod, however truss behavior may be achieved using an alternate configuration as previously noted. Any truss configuration which allows for composite action between the rebar cage  21  and the timber panel  10  would be consistent with the principles disclosed herein. Sections  6   a  &amp;  6   b  are used as reference for the sections shown in  FIGS. 6 a    &amp;  6   b.    
       FIG. 6 a    is a section view cut at a typical cross section of the prefabricated rebar truss  21  illustrated in  FIG. 4 a   . Refer to  FIG. 5 b    for location of section. As shown in this section, the top bar  21 A is pinched between the two inclined diagonal bars  21 B, and a weld is made between these two along this contact. Also shown in this section is the location of the bottom bar  21 C relative to the inclined diagonal bar  21 B. 
       FIG. 6 b    is a section view cut at the end of the prefabricated rebar truss  21  illustrated in  FIG. 4 a   . Refer to  FIG. 5 b    for location of section. As shown in this section, the top bar  21 A sits above the vertical end support bar  21 E and the bottom bars  21 C sit above the horizontal end support bar  21 D. The horizontal end support bar  21 D runs interior to the vertical end support bar  21 E. Each of these bars are connected via welds at the locations of contact. 
       FIG. 6 c    is a section view cut at the end looking perpendicular to the span direction of the prefabricated rebar truss  21  illustrated in  FIG. 4 a   . Refer to  FIG. 5 a    for location of section. This section shows the relationship between the bottom and top bars  21 C &amp;  21 A respectively and the support bars (horizontal &amp; vertical,  21 D &amp;  21 E respectively). Further, this section shows the horizontal segments of the inclined diagonal bars  21 B as well as the termination of the diagonal bars  21 B at the end of the rebar truss  21 . 
       FIG. 7  is a plan view of the illustrative composite action panel shown in  FIG. 2 . This  FIG. 7  shows how the prefabricated rebar truss  21  and the transverse reinforcement  22  are laid out on the timber panel  10  below. A series of rebar trusses running in the direction of the span are placed in a parallel configuration and equally spaced across the width of the timber panel. Similarly, transverse reinforcement bars  22  running perpendicular to the span are placed in a parallel configuration and equally spaced across the length of the timber panel. 
       FIG. 8 a    &amp;  FIG. 8 b    are longitudinal and transverse section views, respectively, of the composite action panel shown in  FIG. 7 . Refer to  FIG. 7  for section cut locations.  FIG. 8 a    shows an exemplary distribution of transverse reinforcement  22  as well as the elevation of the prefabricated rebar truss  21  as it relates to the timber panel  10 .  FIG. 8 b    shows an exemplary distribution of prefabricated rebar trusses  21  across the width of the timber panel  10  as well as the elevation of the transverse reinforcement  22  relative to the top bar  21 A and bottom bar  21 C. Refer to  FIGS. 5 &amp; 6  for details of the rebar truss assembly. 
       FIG. 9  is a plan view of the connectors  30  laid out on the timber panel  10  as shown in the illustrative composite action panel shown in  FIG. 2 . As shown in this figure, the exemplary composite action panel has three steel connector plate types. The typical interior connector plates  31 A are continuous strips of steel plate which run transverse to the composite action panel span and are located to ensure contact between the inclined diagonal bars  21 B (refer to  FIGS. 5 a    &amp;  5   b ) and the interior connector plate  31 A. This contact allows for welding between the interior connector plate  31 A and the inclined diagonal bars  21 C. The end connector plates  31 B are located at both ends of the composite action panel. Similar to the interior connector plates  31 A, the end connector plates  31 B are continuous strips of steel plate which are positioned to ensure contact with the inclined diagonal bars  21 B, allowing for weld between the end connector plates  31 B and the inclined diagonal bars  21 B. End connector plate  31 B size may be adjusted to prevent seepage of wet concrete during the placement of concrete on site. The side connector plate  31 C is a single continuous strip of steel plate located on one side of the timber panel  10 . The edge-most inclined diagonal bar  21 B is welded to the side connector plate  31 C. 
     In this illustrative example, lag screw fasteners  32  are used to connect the connector plates  30  with the timber panel  10 . Alternative connection types include but are not limited to those shown in  FIG. 12 a   - 12   f.    
       FIG. 10 a    is a plan detail of a corner of the timber panel  10  and connector plate  30  assembly. This detail shows the side connector plate  31 C extending beyond the timber panel  10 . This extension allows the connector plate to also function as a pour stop at the end and side connection. Refer to  FIG. 13-16  for more detail on composite action panel end and side connections. It is also possible to extend the end connector plate  31 B beyond the timber panel as required to accommodate the end connection detail, refer to  FIG. 16   a.    
       FIG. 10 b    is a plan detail of a typical edge of the timber panel  10  and connector plate  30  assembly. The prefabricated rebar trusses  21  have been included in fine line form in this detail to illustrate the overlap between these trusses  21  and the connectors plates (interior  31 A and edge  31 C). 
       FIG. 11 a    is a section detail cut at the end of the illustrative composite action panel shown in  FIG. 2  which is consistent with the current disclosure. Refer to  FIG. 9  for section cut location. This detail shows the end connector plate  31 B flush with the timber panel  10  at the end support condition. Refer to  FIG. 13-16  for more detail on composite action panel end and side connections. Although this is used as an exemplary configuration of the end plate  31 B, rebar truss  21  and timber panel  10 , alternative configurations are possible which are consistent with principles disclosed herein. This detail also shows the lag screw fasteners  32  which connect the end connector plate  31 B and the interior connector plate  31 A to the timber panel. Alternative connection types include but are not limited to those shown in  FIG. 12 a   - 12   f.    
       FIGS. 11 b    &amp;  11   c  are additional section details cut through the illustrative composite action panel shown in  FIG. 2  which is consistent with the current disclosure. Refer to  FIG. 9  for section cut location. Similar to  FIG. 11 a    these section details illustrate the fasteners  32  used to connect the interior connector plates  31 A to the timber panel. Further,  FIG. 11 b    shows the contact between the rebar truss  21  and the interior connector plate  31 A. The rebar truss  21  and interior connector plate  31 A are welded together over this contact length. 
       FIGS. 12 a -12 f    are isolated section details looking in the transverse direction of the illustrative panel shown in  FIG. 2 . These details show alternative means of connections which allow for composite action between the rebar truss assembly  21  and the timber panel  10 . Note, means of connecting the rebar truss assembly  21  to the underlying timber panel  10  include, but are not limited to those presented in  FIGS. 12 a   - 12   f.    
       FIG. 12 a    shows lag screw fasteners  33 A connecting the connector plates  30  to the timber panel  10 . In this configuration, the rebar truss  21  is welded to the connector plate  30 . These lag screw fasteners  33 A may also be installed in an inclined orientation as shown in  FIG. 12   b.    
     Alternate means of mechanical connections are shown in  FIGS. 12 c    &amp;  12   d  which include nails  33 B and a punched metal plate  33 C. The punch metal plate  33 C, sometimes referred to as a spike plate, is a component typically used in the construction of timber trusses, but can also serve as a sufficient load transfer mechanism in the current disclosure. Connection between steel and timber components may also be via epoxy methods. This includes but is not limited to connecting the connector plates  30  directly to the timber panel  10  via epoxy  33 D, as well as connecting the rebar truss  21  directly to the timber panel  10  via epoxy. 
       FIG. 13 a    is a perspective view of an illustrative structural system using structural steel for the beam (end  42  and side  43 ) and column  41  framing, and a series of the prefabricated modular composite action panels  50  (refer to  FIG. 2 ) to construct the floor system. Composite action panels are shown representatively in this FIG. and the detailed steel trusses have not been included for clarity. As shown in this exemplary system, the modular floor system panels  50  are installed adjacent to one another and span between end support members  42 . In addition to providing structural stability of the system, side support members are provided parallel to the longitudinal face of the prefabricated modular composite action panels  50  to act as edge support for the end composite action panel. 
       FIG. 13 b    is a plan view of the illustrative structural system shown in  FIG. 13 a   . This plan clearly illustrates the modular nature of the disclosed composite action panels. Prefabricated Modular composite action panels  50  can be shaped and sized based on the structural system geometry to allow repetition of the same module to develop an overall floor system. Shown in this figure is a system using structural steel for framing elements, however, additional systems include but are not limited to reinforcement concrete framing, per-cast reinforced concrete framing, pre-stressed reinforced concrete framing, timber framing and any combination of these framing types. 
       FIGS. 13 a    &amp;  13   b  also illustrate the additional splice reinforcement required at the interface of adjacent composite action panels. Main splice reinforcement bars  25 A and transverse splice reinforcement bars  25 B are required at each interior end and side of the modular composite action panels  50  respectively. Hooked edge reinforcement  25 C is also required around the edges of the floor systems. These additional reinforcement bars can be installed at any point during the transportation and erection process prior to the placement of concrete. 
       FIG. 14  is a section detail taken at the side connection between two adjacent modular composite action panels  50 . Refer to  FIG. 13 b    for location of section cut. This detail shows an exemplary water stop mechanism which prevents the seepage of concrete through a potential seam  11  caused by erection tolerances. Although the detail shown in this example utilizes a thin strip of plywood  14  that may be field installed to connect the adjacent composite action panels and prevent the seepage of wet concrete, alternative water stopping mechanisms include but are not limited to, a thin gauge metal strip (refer to side connector plate  31 C,  FIG. 9 ), tape or a rubber gasket. One might also detail the timber panels  10  to have an offset top ply to allow for a natural overlap of the timber panels as is commonly done in construction using CLT panels as floor panels. 
       FIG. 15 a    is a section detail showing an end support detail of a prefabricated modular composite action panel  50  supported by a steel wide flange beam at an interior support condition  41 A. Refer to  FIG. 13 b    for section cut locations. In this illustrative detail both adjacent timber panels  10  are bearing directly on the steel end support beam flange  41 A. The prefabricated modular composite action panels  50  are sized and erected to ensure composite beam action can be achieved between the end support member  41 A and the concrete  40  via the steel shear stud  44 . Additional main splice reinforcement  25 A are provided across the support line to achieve slab continuity. An erection strap  15  or equivalent is required in this configuration to ensure stability of the prefabricated modular composite action panel  50  during the temporary condition, prior to the placement of concrete. Alternative means of providing temporary stability include but are not limited to, timber to steel bolted connections and timber to timber connections. 
     Alternative interior panel end support methods include but are not limited to those shown in  FIGS. 15 b    &amp;  15   c . As shown in  FIG. 15 b   , the connection may be made by direct bearing of the end connector plate  31 B and the end support beam  41 A. The connection may also be made by running a continuous timber panel  10  across the top of the support beam  41 A as shown in  FIG. 15 c   . In the case of the detail illustrated in  FIG. 15 c   , additional considerations are required to notch the timber panel  10  to ensure composite action between the support beam  41 A and the concrete  40 , if composite action is desired. 
       FIG. 16 a    is a section detail showing an end support detail of a prefabricated modular composite action panel  50  supported by a steel wide flange beam at an edge support condition  41 A. Refer to  FIG. 13 b    for section cut locations. Similar to  FIG. 16 a   , the timber panel  10  is bearing directly on the steel end support beam flange  41 A. Also, similar to  FIG. 16 a   , the prefabricated modular composite action panels  50  are sized to ensure composite beam action can be achieved between the end support member  41 A and the concrete  40 . The edge of slab top reinforcement  26 A at this location is hooked as per typical reinforced concrete detailing standards, and edge of slab nosing bars  26 B are provided as shown in this exemplary detail. Refer to  FIG. 15 b    description above for information on alternative exterior end support configurations shown in  FIG. 16   b.    
       FIG. 17 a    is a section detail showing an end support detail of a prefabricated modular composite action panel  50  supported by a reinforced concrete beam at an interior support condition  41 B. Refer to  FIG. 13 b   , section  15   a  for section cut locations. As shown in this detail, the timber panel  10  is supported by beam formwork  12  used to form the interior concrete end support member  41 B. The potential performance of the beam formwork  12  includes, but is not limited to, temporary formwork which is removed after the curing of concrete, permanent formwork which is left in place for the duration of the structures lifespan or as a permanent integral part of the structural system which is composite with the concrete beam. The beam formwork may or may not require additional shoring  13  and still be consistent with the current disclosure.  FIG. 16 a    is a section detail showing an end support detail of a prefabricated modular composite action panel  50  supported by a steel wide flange beam at an edge support condition  41 A. Refer to  FIG. 13 b    for section cut locations. 
     Regarding the sequence of installation, in this illustrative example, the beam formwork  11  would be installed first, then the prefabricated modular composite action panel  50 . Lastly the beam stirrups  27 B, longitudinal bars  27 A and main splice reinforcement  25 A are installed. It is also possible for some of these components to be integrated together to increase speed of construction. 
       FIG. 17 b    is a section detail showing an end support detail of a prefabricated modular composite action panel  50  supported by a reinforced concrete beam at an edge support condition  41 B. Refer to  FIG. 13 b    section  16   a  for section cut locations. Refer to  FIG. 17 a    description for discussion on beam formwork  11  configuration and erection sequence. As shown in this section, the main splice bar  25 A for an exterior concrete end support element  41 B is hooked into the beam. 
       FIG. 18  is a perspective view of a potential hoisting configuration of a single prefabricated modular composite action panel  50 . As shown in this figure, the composite action panel  50  can be lifted by 4 connection points  52 B at which secondary cables  52 A connect, and tie back to the primary cable  54 . The present disclosure allows for hoisting directly from the rebar cage. Additional fasteners are provided as required at hoist connection points to ensure adequate withdrawal capacity is available. Additional hoisting hardware may be included on the prefabricated modular composite action panel to increase connection capacity as required. Although this figure only illustrates a single composite action panel being hoisted, it is possible to hoist multiple composite action panels at a single time. 
       FIG. 19 a    is a general flow chart outlining the primary steps and materials involved in the fabrication and erection of a modular composite timber floor system consistent with principles disclosed herein. As shown in this figure and described in detail above, the timber panel  10 , connectors  30  and steel reinforcement elements (rebar truss)  20  make up the prefabricated modular composite action panel  50 . However, prior to fabrication of any composite action panel, detailed shop drawings of individual composite action panel pieces as well as the erection drawings must be generated to establish the geometry of each composite action panel to be fabricated. This detailing step may be done with traditional 2-dimensional shop drawings, or by using parametric 3-dimensional documentation tools. Once the composite action panel geometries are established through the documentation process, the composite action panels are fabricated.  FIG. 19 b    provides a flow chart detailing a suitable fabrication process, preferably performed in a shop or off-site from where the composite action panels are to be installed. After the composite action panels are shop fabricated, they can be shipped to the site where they are erected based on the erection plans.  FIG. 19 c    provides a flow chart detailing an erection process. Once erected, concrete is placed (poured), resulting in a structural system, which in this illustrative embodiment is a monolithic floor or roof system. 
     With continuing reference to  FIG. 19A , in step S 1 , the detailed shop drawings of individual composite action panel pieces as well as the erection drawings are generated to establish the geometry(ies) of each composite action panel to be fabricated. In step S 2 , the timber panel  10  and the steel reinforcement elements  20  are secured to each other by way of connectors  30 , such as those described above. In step S 3 , the prefabricated composite action panel results. In step S 4 , the prefabricated composite action panel is transported to an erection site. In step S 5 , the prefabricated composite action panel (and typically others) is placed into position at the erection site, for example, as a floor member, wall member, or ceiling member and temporarily joined with other structural components as described above such as other composite action panels, and concrete is poured into the form. Once the concrete (or cementitious material) has cured, the additional form members are removed in step S 6  and the result is an installed modular composite timber and truss panel, which in  FIG. 19A  is described as a floor panel as an example only. 
       FIG. 19 b    is a flow chart outlining the fabrication process of a single modular timber floor system panel consistent with principles disclosed herein. As shown in this fabrication flowchart, each component of the prefabricated modular composite action panel has unique fabrication requirements at the front end of the process (reference steps S 3 . 1 -S 3 . 3 ). Once each component is fabricated, they are combined to form a composite action panel. Depending on the connection methodology, the fabrication steps during the connection sequence vary, Refer to  FIG. 12 a -12 f    and the related description above for and understanding of these various connection types. 
     With continuing reference to  FIG. 19 b   , in step S 1 , the detailed shop drawings of individual composite action panel pieces as well as the erection drawings are generated to establish the geometry(ies) of each composite action panel to be fabricated. In steps S 2 . 1 , S 2 . 2  &amp; S 2 . 3 , raw materials are procured for fabrication of each individual component. In steps S 3 . 1 , S 3 . 2 , and S 3 . 3 , each composite action panel component is fabricated to the specified geometries per the individual piece drawings. The timber panel can be fabricated using standard industry techniques. The connectors can be fabricated by cutting plate pieces to length/size and then drilling holes in the plates. The reinforcement elements (steel truss) can be fabricate by cutting steel bars to length, bending the diagonal bars into the galloping shape and then welding all of the bars together as described above. 
     In steps S 4 . 1  and S 4 . 2 , additional prep work is performed on the timber panel as required per the specified connection type. In this example, it is determined if epoxy connections are to be used. If yes, then the timber panel is either routed to provide pockets to receive the connection plates or ripped to provide dado grooves for the connection plates. 
     In step S 5  the steel reinforcement elements (steel trusses) are connected to the connector plates based on the methods described above. In this embodiment, they are welded together. Alternatively, if the steel trusses are shipped individually and the connector plates are connected to the timber panel independent of the steel truss, this step can be performed later in the process, for example, in step S 8 . 
     In step S 6 , the transverse reinforcement (transverse rebar) is installed. Note, if the steel trusses are shipped individually and the connector plate is connected to the timber panel independent of the steel truss, this step can be performed later in the process, for example in step S 9 . In steps S 7 . 1 , S 7 . 2 , S 7 . 3  the connector plates are attached to the timber panel based on the selected method. In step S 7 . 1 , connector plates are attached using self-tapping lag screw. Alternatively or additionally, in step S 7 . 2  connector plates are attached using nails and minimal self-tapping screws. Alternatively or additionally, in step S 7 . 3  the connector plates are attached to the timber panel using epoxy. As can be appreciated, typically, only one type of attachment method would be used, but, depending on the requirements and/or circumstances, two or more attachment method may be used. 
     As mentioned above, if the steel trusses are shipped/transported individually, steps S 8  and S 9  can be performed. In step S 8 , the steel trusses would be welded to the connector plates. In step S 9 , the transvers rebar would be attached. 
       FIG. 19 c    is a flow chart outlining the erection process of a single prefabricated modular timber floor system panel consistent with principles disclosed herein. As shown in this flowchart, the present disclosure may be implemented in a building or other structure that is constructed using a wide range of material types. Depending on the base building material type, various construction techniques may be implemented to create a structurally stable system allowing installation of panels one at a time, or in groups. Depending on the end connection detailing, panels may require temporary connections to be made, thus ensuring stability of the system prior to the placement of concrete. 
     The following is a basic description of an exemplary construction process consistent with the flow chart provided in  FIG. 19 c    which may be used to construct a floor slab system using this disclosure: 
     In a step  10 , a determination is made as to the type of building structural material to be employed. In this description, three types are shown: steel, concrete, and heavy timber. The type of building structure material impacts the way in which the support framing is erected and support details for the composite action panels. 
     In step S 11 . 1 , steel framing is erected for steel structures. In step S 11 . 2 , pre-cast elements such as columns, walls, braces and beams are erected for pre-cast concrete buildings. Alternatively, in step S 11 . 3  forms into which concrete is to be poured are erected for the structural elements such as columns, walls and braces. In step  11 . 4 , timber framing is erected for timber buildings timber as the structural material. 
     If the building structural material is non-precast concrete, i.e., cast-in-place concrete, following step S 11 . 3 , in step S 12 , the support framing is formed by pouring concrete into the forms erected in step S 11 . 3  to create, e.g., the vertical structural elements. Support framing may be constructed using any commonly accepted building materials and techniques. This specification discloses flexible connection details allowing the composite action panels to be installed using a variety of support types. In step S 13 , temporary or permanent formwork for floor beams is install. 
     In steps S 14 . 1 , S 14 . 2 , and S 15  the prefabricated composite action panels are hoisted into place. In S 14 . 1  plural panels are hoisted to a staging location. And then in step S 14 . 2 , the composite action panels are distributed and placed in their final locations. Alternatively, in step S 15 , an individual composite action panel is hoisted into place. The exact location of a composite action panel depends on the modular layout of all panels, e.g., on a given floor, and is also dependent on the support type and allowable construction tolerances of the support. 
     In step S 16 , it is determined whether the rebar cage will extend beyond end of CLT. If the answer is no, then in step S 17 . 1  the composite action panels are secured in place, with the requirements for securing the composite action panels being based on end connection type. If the answer is yes, then in step  17 . 2 , splice reinforcement and additional edge reinforcement for the composite action panels are installed as noted above. Typical mild reinforcing steel bar is used for splices between adjacent panels, however alternative splice details which are accepted by the authority having jurisdiction for a given project may also be employed. 
     In step S 18 , concrete is poured and the composite action panel steel stiffening members are embedded in the concrete. Shoring can be provided as needed for the composite action panels and/or support beams prior to the pouring of concrete. 
     In step S 19 , any temporary formwork and shoring is removed. 
     In step S 20 , protective layers from the timber panel (i.e., that surface of the timber panel that is to be left exposed) are removed. If the composite action panels are used in a flooring system, the timber can be left exposed to provide a timber panel ceiling for a lower floor. 
       FIG. 20  is a perspective view showing a single bay of an exemplary structural system  60  and identifies the primary element types used in a typical structural system. This  FIG. 20 , in combination with the  FIGS. 21 a -21 c    and the preceding figures will be used to describe how the modular composite action panel disclosed herein can also be applied to the other typical elements of a structural system. In this way, it is possible that the embodiment described in this disclosure be used to form the entire structural system of a building or individual elements apart from slab elements which have been described in detail through the previous figures. 
     The typical elements shown in this exemplary single bay system are the slab  50 A incorporating one or more composite action panels, beam elements  61 , column elements  62 , braces elements  63  and wall elements  64 . Refer to the first paragraph of the detailed description portion of this specification for a description of slab elements  50 A performance characteristics. Beam elements  61  are horizontal elements which support the slab  50 A and are supported by column elements  62 , wall elements  64  or other beam elements. Column element  62  and wall element  64  are vertical elements which support slab element  50 A and beam element  61  and transfer building loads to the foundation system. Brace elements  63  are diagonally oriented, and typically connected adjacent vertical elements, but can also connect beam elements to vertical elements. 
       FIG. 21 a    is a perspective view illustrating the primary components of a prefabricated modular timber beam element  61 . Similar to the composite action panels described in detail above and illustrated in the earlier figures, the beam element consists of timber panels  10 , connector elements  30 , and steel reinforcement  61 A. As with the composite action panels, the timber  10  and steel reinforcement elements  61 A are prefabricated off site and joined together and then transported to an installation site as a modular package making for rapid and precise installation. The two elements, timber  10  and steel reinforcement  61 A can be made to act compositely by coupling them with the connector elements  30 . Unlike the slab element  50 A, the beam element  61  can have three outer sides of timber, creating a trough in which concrete can be placed on-site. An additional tie element  61 B can be provided as required to stabilize the vertical portions of the beam element  61  in the temporary condition. 
       FIG. 21 b    is a perspective view illustrating the primary components of a prefabricated modular timber column element  62 . This configuration is also applicable for the prefabricated modular timber column element  63 . Similar to the previous elements described, the column  62  (and brace  63  of  FIG. 20 ) consist of prefabricated timber panels  10  joined with steel reinforcement  62 A using connector elements  30 . The column and brace elements are unique in that they have four outer sides of timber which form a hollow tube. Following erection, concrete is placed in the tube, creating a structural element with potential composite behavior consistent with the previous descriptions offered in this disclosure. Similar to the beam elements and consistent with standard construction practices, ties are provided which connect opposing timber faces to ensure stability under the hydrostatic pressure of wet concrete. 
       FIG. 21 c    is a perspective view illustrating the primary components of a prefabricated modular timber wall element  64 . Wall elements  64  consist of timber panels  10  prefabricated with steel reinforcement  64 A via a connector element  30  on the interior face of each composite action panel. Two composite action panels can be installed opposite each other with stabilizing cross ties  64 B, leaving space between the composite action panels for concrete to be placed on-site. Each composite action panel can be installed separately, or a pair of composite action panels can be prefabricated together and installed as a double-sided wall form. The outer sides of the wall element will then be made of timber. 
     The forgoing description of an implementation of the disclosure has been present for the purpose of illustration and description. It is not exhaustive and does not limit the disclosure to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practicing the disclosure. Accordingly, while various embodiments of the present disclosure may have been described, it will be apparent to those of skill in the art that many more embodiments and implementations are possible that are within the scope of this disclosure. Accordingly, the present disclosure is not to be restricted except in light of the attached claims and their equivalents