Connectors for Joining Timber Structures

This application claims priority from U.S. application No. 63/569,387 filed 25 Mar. 2024 entitled A CONCRETE CONNECTOR FOR JOINING TIMBER BUILDING ELEMENTS (A.K.A. TIMBER CONCRETE NODE OR TCN). This application claims the benefit under 35 U.S.C. § 119 of U.S. application No. 63/569,387 filed 25 Mar. 2024 entitled A CONCRETE CONNECTOR FOR JOINING TIMBER BUILDING ELEMENTS (A.K.A. TIMBER CONCRETE NODE OR TCN) which is hereby incorporated herein by reference for all purposes.

The present invention relates to timber connectors, in particular those for use to join mass timber structural components in building constructions. cl BACKGROUND

Mass timber structures (including solid heavy timber and engineered timber) require connections between timber structural components, including beams, columns, posts, purlins, and walls. These connections are typically made with metal ‘hangers’ that are screwed or nailed into the beams/columns/purlins/walls. High-capacity metal hangers exist, but they are expensive and susceptible to damage by fire. To protect against fire, they require supplemental protection via coatings or sacrificial timber cover. Metal hangers typically require tight installation tolerances. For beams connecting on either side of a single timber column two metal hangers are typically required.

There is a general desire for improved connectors for timber structures, and more particularly, for joining mass timber structures.

The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.

The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements.

Aspects of the present invention pertain to a structural connector. The structural connector is made of a material comprising concrete. The concrete connector is a fire-resistant connector. The concrete connector may be made of reinforced concrete configured to join mass timber structural components. Such concrete connectors may be referred to as a “Timber Concrete Node”, or “TCN”). The TCN can join mass timber structural components efficiently and securely. The TCN may be made in a variety of shapes and sizes, to suit the size of the timber structural components that are desired to be joined and the strength required for the connection. The TCN advantageously eliminates the need for costly and fire-susceptible metal connectors or hangers. In some embodiments, the TCN incorporates void channels that are cast into the concrete to accommodate fasteners such as self-tapping screws, thereby facilitating robust fastening to timber elements. Additionally, the TCN may provide alternative fastening options such as supplementary plates, rods, or dowels cast into the concrete. The modular design of the TCN allows the connector to support a wide range of structural demands while maintaining easy handling and installation. The TCN design facilitates onsite casting or pre-casting. With lightweight, normal weight, or ultra high-performance reinforced concrete, the TCN ensures structural integrity while providing a durable and versatile solution for assembling mass timber structures.

In some embodiments, in the most basic form, the TCN is a rectangular prism of precast concrete which attaches to the top side of a column. The TCN cantilevers beyond the face of the column and supports the bottom of 1 or 2 beams (which may be notched so the bottom of the beam is flush with the bottom of the TCN). In some embodiments, The TCN has a width which is the same or substantially the same as the timber elements that it is connecting. In some embodiments, the TCN has a width which is less than that of the timber. In such embodiments, the concrete connector may be partially surrounded by the timber.

Aspects of the present invention pertain to structural assemblies comprising at least two timber structural components being joined by one or more concrete connectors. The at least two timber structural components may comprise timber purlins, beams, columns, posts, walls, etc.

Further aspects of the invention and features of specific embodiments of the invention are described below.

Throughout the foregoing description and the drawings, in which corresponding and like parts are identified by the same reference characters, specific details have been set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail or at all to avoid unnecessarily obscuring the disclosure.

“Timber” refers to wood extracted from trees that is suitable for use as a structural component in the construction of buildings, bridges, and other structures. The timber as used herein includes unprocessed timber (or raw timber) and processed timber. One non-limiting example of a type of “processed timber” is “mass timber”.

“Timber structural components” or “timber structures” are solid, structural, load-bearing components that are made with timber, such as purlins, beams, columns, posts, walls, etc.

“Mass timber” refers to a type of solid or engineered wood products that is suitable for use as a structural component in the construction of buildings, bridges, and other structures. Mass timber is typically made by fastening multiple layers of wood products such as by glue, nail, dowel, etc. to produce a larger structural component such as panels, posts and beams, etc. Non-limiting examples of mass timber products include cross-laminated timber (CLT), dowel-laminated timber (DLT), nail-laminated timber (NLT), glue-laminated timber (Glulam or GLT), laminated strand lumber (LSL), laminated veneer lumber (LVL), parallel strand lumber (PSL), etc.

“Concrete” refers to a material composed of binder(s) and aggregates such as sand and gravel. As used herein, “concrete” includes any suitable type of concrete including but is not limited to one or more of ordinary or normal strength concrete (e.g., concrete that uses the common mix design of 1:2:4 of cement, sand and aggregates), lightweight concrete (e.g., concrete which has a density of less than about 1920 kg/), high-density concrete, high-strength concrete (e.g., concrete mix that is greater than about 40 megapascal (40 MPa), high-performance concrete (HPC), ultra high-performance concrete (UHPC), reinforced concrete, etc. In some preferred embodiments, the concrete comprises a self-consolidating concrete with small aggregate to reduce voids and produce a high-quality surface finish.

“Precast” means that the material (e.g., concrete) is cast into the desired form before being transported to the site of installation. For example, the concrete may be poured into a preshaped mold at a plant, and left to cure in a suitable environment. Once cured, the mold is removed and reused. The precast concrete may be transported to the site of installation.

Referring to, in one embodiment, the invention is a structural connectoradapted to join timber structural components. The structural connectoris made of a material comprising an amount of concrete that is more than 90% of the total volume of the connector, and in some embodiments, more than 95%, and in some embodiments, more than 97%. In some example embodiments, the total volume of voids in the concrete connectoris in the range of from about 1% to about 5%, and in some example embodiments, between about 2% to about 3%. The voids may for example be provided to accommodate one or more fasteners and/or reinforcing members. As used herein the term “about” provides literal support for the exact numerical value that it precedes, the exact numerical value ±5%, as well as all other numerical values that are near to or approximately equal to that numerical value.

The structural connector(which may be referred to herein as a concrete connector) of the present invention is highly resistant to fire, thereby making such connector an attractive alternative to the conventional metal connectors for timber structural components that are used in building constructions. The concrete connector described herein may also be referred to herein as a “Timber Concrete Node” or “TCN”.

In some embodiments, the connector is made of a material comprising fiber-reinforced concrete. The fibers in the fiber-reinforced concrete may be distributed throughout the concrete mix. The fibers that make up the fiber-reinforced concrete may for example comprise one or more of natural fibers (e.g., plant fibers), synthetic fibers (e.g., polypropylene fiber (PP), polyvinyl alcohol fiber (PVA), polyethylene fiber (PE) and nylon (PA), etc.), glass fibers, and steel fibers. In some embodiments, the amount of fibers in the fiber-reinforced concrete is not more than about 2% of the total volume of the concrete and in some embodiments, not more than about 1% v/v, and in some embodiments, not more than about 0.5% v/v.

In some embodiments, one or more reinforcing membersare embedded in the concrete of the concrete connector(see e.g.,). The one or more reinforcing membersare provided to increase tensile strength of the concrete. The reinforcing membermay for example be arranged to extend along a longitudinal axis of the concrete connector, or in along a direction that is transverse to the longitudinal axis of the concrete connector. The one or more reinforcing members may be precast into the concrete.

In some embodiments, the reinforcing membercomprises one or more reinforcing bars (or rebar) such as steel reinforcing bars. However, other suitable reinforcing members may be used such as but is not limited to bars such as fiberglass bars, threaded rods, mesh panels, etc. In embodiments in which a plurality of reinforcing members are provided, the plurality of reinforcing members may be arranged to extend in one axis direction of the concrete connector.

In some embodiments, the concrete connectoris made of a fiber-reinforced concrete that is additionally reinforced by one or more reinforcing members such as one or more rebars.

In some embodiments, the compressive strength of the concrete connectoris about 25 to about 35 MPa, and in some embodiments, greater than about 150 MPa. The concrete can be made from conventional mix designs or very high strength formulations in the case of ultra-high performance concrete.

Referring to, in some embodiments, one or more mounting channelsare defined within the concrete connector. The mounting channelmay be precast into the concrete. In some embodiments, the mounting channelextends along the longitudinal axis of the concrete connector, from one surface to an opposite surface of the concrete connector. In some embodiments, the mounting channelextends along a direction transverse to the longitudinal axis of the concrete connector, from one surface to an opposite surfaceof the concrete connector. A fastenermay be insertable through each one of the mounting channelsfor fixedly securing the concrete connectorto the timber structural component. The fasteneris arranged to protrude from the surfaceof the concrete connector.

Any suitable fastenerswhich can penetrate timber structural componentsto securely attach the connectorthereto may be used, including but are not limited to partially threaded and/or fully threaded screws (e.g., self-tapping screws), rod, dowel, plate, etc. The fastenermay be oriented orthogonal (i.e.,) 90° relative to the surfaceof the concrete connector, or inclined at an angle (such as by about 15 to 45°) relative to the surfaceof the concrete connectorso that the fastenerapproach the wood end grain at an angle.

In some example use embodiments, at least one concrete connectoris arranged between two timber structural componentswhich are desired to be joined. One concrete connectormay however be joined to more than two timber structural components.

Referring to, in some embodiments, a plurality of concrete connectorsare fixed connected together to form a combined concrete connectorwhich allows it to comprise two lighter weight parts that combine to have the same bending resistance as if it was one solid cast part. In some embodiments, one or more reinforcing memberssuch as steel bolts is used to secure the plurality of concrete connectorsto form the combined concrete connector. As an example, the reinforcing membermay be inserted through a precast mounting channelprovided in the concrete.

The concrete connectormay comprise a shape and/or dimension that is suitable for connecting the timber structural componentswhich are desired to be joined. The concrete connectordescribed herein may be used to join any combination of timber purlins, beams, columns, posts, walls, etc. For example, the concrete connectormay be used to join purlin to beam, purlin to wall, purlin to column, beam to wall, beam to beam, beam to column, and when used as a splice, the concrete connectormay also be used to join column to column, or post to post.

illustrate different relative sizes and/or shapes of the concrete connectorfor arranging the concrete connectorto join a plurality of timber structural components.also illustrate example configurations of arrangement between the concrete connectorto join the plurality of timber structural components.

In some example embodiments, the concrete connectorhas a shape of a rectangular prism. The concrete connectormay comprise a rectangular-shaped cross-section along a longitudinal axis of the connector.illustrate example embodiments of how the concrete connectormay be arranged to join one or more columns to one or more beams.

In some example embodiments, the concrete connectoris arranged such that surfaces of the connectorare positioned to contact a respective end of one or more beams and columns. In some embodiments, the concrete connectorhas a width which is the same or substantially the same as the timber structural componentswhich the connectoris arranged to join.

In some example embodiments, the concrete connectoris arranged to be received within a receiving slot of one or more of the timber structural componentswhich the connectoris arranged to connect. In some embodiments, the concrete connectorhas a width which is less than that of the one or more timber structural componentswhich the connectoris arranged to connect.

In some example embodiments, the concrete connectoris arranged such that surfaces of the connectorare positioned to contact a respective end of one or more beams and columns. In theembodiments, an endof a timber columnis joined to a lateral faceof the concrete connector. An endof the second timber columnmay be arranged to contact the opposing second lateral faceof the concrete connector. Two adjoining timber beams,each comprises a recessed corner edge,. Each of the recess corner edges,are dimensioned to contact a respective base,and a respective portion of the lateral faceof the concrete connector. A plurality of mounting channelsA,B,C may extend along a direction transverse to the longitudinal axis of the concrete connector, from one lateral faceto the opposing second lateral face. A fastener may be inserted through each one of the mounting channelsA,B,C to secure the concrete connectorto the beams,. In theembodiments, the width of the concrete connectoris the same as, or similar to, that of the column,and the beams,.

illustrates an embodiment in which the width of the concrete connectoris less than that of the column. In such embodiment, the columnmay comprise a receiving slotat an endthereof. The concrete connectormay be inserted through the receiving slotof the column. In such embodiments, the columnmay be arranged to partially encompass the concrete connector.

illustrates an embodiment in which the width of the concrete connectoris less than that of the columns,and the beams,. In such embodiments, the columncomprises the receiving slotat the endthereof. The beams,each comprise a receiving slot,at the respective ends,thereof. The concrete connectormay be inserted through the receiving slotof the column, and the receiving slots,of the beams,. In such embodiments, the column, and the beams,both encompass the concrete connector.

illustrate an embodiment in which a continuous timber columnis provided. In such embodiments, a receiving channelis defined through the columnbetween opposing lateral faces,of the column. The receiving channelis dimensioned for receiving the concrete connector. The recessed corner edges,of the beams,are arranged in contact with the respective bases,and respective portions of the lateral faceof the concrete connector.

illustrate an embodiment in which the concrete connectorhas an “I”-shaped cross-section along the longitudinal axis of the connector. An “I”-shaped concrete connectormay desirably reduce the weight of the connectorand/or increase the thickness of the remaining timber on the face of the column. In some embodiments, the “I”-shaped cross sectional concrete connectoris joined to an endof a timber columnon a lateral faceof the connector. In such embodiments, the concrete connectorcomprises a receiving slot(one is not shown) each defined on a respective opposing lateral faces(one is not shown) of the connector. The lateral faceis orthogonal to the lateral faceon which the connectoris joined to the timber column. The receiving slotsare each dimensioned to be received within a receiving channeldefined at an endof the second timber column. When assembled, the endof the second timber columnmay be in contact with the endof the timber column.

illustrate an embodiment in which a plurality of concrete connectorswhich are coupled together (e.g., by bolting) to form one combined concrete connectorfor connecting beams,to the continuous column.illustrate the coupling of two concrete connectorsA,B which comprise a “T”-shape along the longitudinal axis of connector; however, this is not mandatory. The concrete connectorsA,B may have any suitable shapes such as a rectangular prism.

illustrates an example structural assembly which comprises a plurality of purlinsjoined to a plurality of beams,and columnsby a plurality of concrete connectors.

is a close-up view showing one of the connections between the purlin, beams,and columnwith two concrete connectorsA,B.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the scope thereof. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.