Block Strap for Shear Panel Diaphragms

Abstract

Plywood shear panel diaphragms are utilized in building walls and roofs to support against lateral forces such as earthquakes, wind, tornadoes, and hurricanes. Plywood is typically used for the shear diaphragm in wood construction, nailed vertical or horizontal to wood members. When introducing an opening in a plywood shear panel diaphragm, the diaphragm becomes weakened. Shear transfer process is required to maintain integrity in the shear diaphragm at the opening. The strength from the diaphragm is transferred to the openings edges, the top and bottom edges, using blocks between the framing members acting in compression, and the strap, which acts in tension, transfers the support of the diaphragm to opening. When compared to conventional means, the Block Strap apparatus is a better, more accurate, predictable, cost cutting, labor reducing product for providing for shear transfer requirements in typical common wood construction.

Description

CROSS REFERENCE TO PENDING APPLICATIONS

This application claims benefit of prior filed co-pending provisional application No. 62/467,508 entitled “Block Strap” is a manufactured integral two component single piece of metal hardware that provides blocking and strapping for shear transfer support to an opening from a vertical or horizontal plywood shear panel diaphragm in a wood framed wall or roof” filed on Mar. 6, 2017 in the name of Daniel Lester Varnum of Moorpark, Calif., said provisional application being hereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

The purpose of this invention is to reduce labor, material costs, in the framing of buildings. Current methods are labor intensive and can be prone to errors in installation causing a reduction in the shear strength of the framing and or possible failure. Also, one of the major causes of cracking or sagging around windows and doors is from movement in the wall, which causes the windows to bind and doors not to properly open or close. Blocking and strapping is done at around the opening in to the diaphragm to strengthen the opening and lessen the moment at the shear diaphragm because of the opening.

The standard conventional method for blocking and strapping is done by using wood blocks and a metal strap, all installed separately. This is a labor intensive process. The standard conventional method also has problems with poor quality in installations, splitting of the wood blocks from nailing, poor quality in cutting material, and material waste from cutting blocks from wood beam stock. Conventional means requires multiple steps to make and install, thus creating costly time in labor.

As the conventional method uses cut blocks from wood beam stock, there are multiple saw passes required when cutting the blocks to the correct length. The blocks are handled one by one and nailed at each end into the wall stud or roof rafter by means of toe nailing. Toe nailing is driving a nail at an angle, which is a common method often used to fasten wood materials together; wood blocks to wood studs or roof rafters. Toe nailing often causes the wood block to split. As toe nailing is usually done parallel with the grain of the wood and only penetrates approximately 1 inch into the end of the block, the nail can easily breakdown the grain structure separating layers there by weakening the block connection to the stud or rafter. Studies show that 75% of the strength of the block is compromised when the grain is split. Though it is proper to remove split blocks, many contractors will not, and the blocks will be covered with plywood shear hiding the errors from engineers and or building inspectors. Blocking and strapping is provided in shear walls when shear walls are designed with openings. Blocks are installed between the studs in line with the top and bottom of the openings. Metal straps, commonly known as “Simpson Straps” or Collector Straps, are then nailed to the blocks and header or sill at the opening. This reinforces the opening by tying the opening to the blocked studs and plywood diaphragm, thereby creating a torsional or transactional resistance to a load, (moment), placed on the opening by shearing forces. In its normal practice, there are at least three blocks installed on each side of an opening, and then after the sheathing is installed, straps are nailed into position each side of the opening. Installing three conventional cut wood blocks requires a 10 step process, where the apparatus disclosed herein, reduces the steps to two with a guaranteed holding strength due to proper blocking.

In this disclosure of the apparatus, the “Block Strap” apparatus is a manufactured single piece, multi component piece of hardware installed in only two steps. Blocks are pre-attached to a steel or aluminum strap. The blocks and strap are made of materials that are appropriate for the loads to be resisted. Walls or roof designed with openings in a shear diaphragm create a weakening in the diaphragm. Shear forces from wind, earthquake and vertical loading create shearing stress to the openings. Engineers or architects will specify the type and size of lumber and hardware to be used to create the proper resistance to the shearing forces in the diaphragm. Because the blocks of this invention are not nailed to any wood members, and are usually manufactured in metal or recycled construction grade polymers, they will not split. The lengths are accurate and fit snug between the framing members. There is also no waste of wood materials in that it is manufactured metal or polymer product. The apparatus can be mass produced.

SUMMARY OF THE PRIOR ART AND STATE OF THE ART

Buildings are structurally designed to transfer all gravity, uplift, and lateral loads to the foundation. In wood framing, the structural systems typically consist of the roof structure that supports the roof deck and floor framing that supports the floor. Supporting components for these systems are exterior and interior load-bearing walls, beams, girders, rafters, floor joist and posts. In the structural engineering the bearing walls and roof decks become shear diaphragms. This is a structural system composed of braced panels, (also known as shear panels), to counter the effects of lateral load acting on a structure. Wind and seismic loads are the most common loads that shear diaphragms are designed to resist. A wall or roof diaphragm is a structural element that transmits lateral loads that act upon the vertical or horizontal resisting elements of the structure. A shear wall is simply a cantilevered diaphragm to which load is applied at the top of the wall through a top plate and is transmitted out along the bottom of the wall along a sole plate. The sole plate or bottom plate is held down by bolting to the foundation. Because of this load path, each component in the load path needs to have capacity of transferring the full load for a shear wall to work as expected. Shear diaphragms are vertical or horizontal in nature, as stated a horizontal roof deck or vertical wall. Horizontal diaphragms can be sloped such as in a gable roof or a hipped roof in a wood structure. Shear walls in wood framed structures with windows or other large openings such as doors must be structurally connected through the opening to the diaphragm so as to maintain the resistance of the lateral forces put upon the load path that acts upon the diaphragm. This is usually done with extra vertical members to resist the vertical compression loads and a header over an opening, which allows for the vertical load of the opening to be carried horizontally across the opening. This horizontal header must be tied or connected to the vertical members using blocking and strapping between and to the studs, respectfully, so as to transfer the lateral forces put on the opening to the shear wall diaphragm to reduce the moment.

The integrity of the overall building depends not only upon the strength of the structural components, but also on the adequacy of the connections that exist between them. Critical connections occur throughout the structure, but in wood framed structures, the most critical connections exist where there are window and or door openings in shear walls or roof diaphragms. Current and conventional method of securing these critical connections is through the use of wooden blocks placed between the studs immediately next to the opening and a steel strap that joins the blocks and studs to the top and or bottom of the opening thereby distributing the shear loads to the opening from the adjoining framing members. As detailed, this current method is fraught with potential damaging issues which subject the building to stresses not planned for.

The apparatus disclosed in this disclosure consists of series of fabricated blocks, preferably recycled metal or polymer, and an elongated metal strap of specific length and gauge metal. The blocks are of specific gauge metal, and are rectangular in shape. The blocks have a specific width, depth and height. There can be two blocks, three blocks or however many is required. The number of blocks that are attached to the strap depends on the length of the strap required. The strap is permanently attached to the blocks during the manufacturing process. Depending on the size of the opening and the amount of shear stresses that are being placed upon the opening, the number of blocks and length of the strap will vary.

This invention is an improvement on what currently exists because it is a one piece manufactured metal product component with multiple blocking configurations which is very predictable and reliable in its structural integrity. The invention is accurate in size and measurement, and with no defects before and after installation. It is mass produced and easily and quickly installed.

A structural engineer or architect, in the structural construction documents, would specify a particular Block Strap from a catalog of choices. The choices made would depend on the lateral stress requirements to support from the plywood shear panel diaphragm to an opening in the diaphragm. With consistency in the manufacturing process and ease of installation, the straps will resist the stresses as designed, where currently split wood blocks will not resist the stresses as designed.

The metal blocks and strap would be machine fabricated, formed and manufactured. The strap would be welded to the blocks. The apparatus is integral piece of hardware consisting of metal strap and multiple blocks. The strap and block become integral by means of positive permanent connection of the two entities. The permanent connection is made during the manufacturing process.

Quick install set tabs would be fabricated in the strap to preset the component. This would set and give stability to the component in order to complete the required installation of nailing of the strap to the wood roof rafters or wood studs and to the header over an opening. This allows for one man installation of this new strap.

BRIEF SUMMARY OF THE INVENTION

Accordingly, it is the goal of this invention to create an apparatus that will enable contractors to properly block and frame an opening in a plywood shear panel diaphragm with a single piece of material that will ensure proper placement and quality of the blocking and strapping thereby ensuring that the calculated shear values that the architect or engineer had specified will be obtained in actuality.

It is another object of this invention to create an apparatus that can be specified by architects or engineers that will possess the proper structural components that will ensure that calculated loads are properly secured without having to rely on possibly inferior wood and block placements by contractors.

It is another object of this invention to create an apparatus that can have multiple variants easily selected from stock with set shear load resisting capabilities that can be mass produced.

It is an embodiment of this invention to create a single apparatus which incorporates two of the single apparatuses which will aid in assembly and proper construction to facilitate the planned shearing values.

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1, the frontal elevation is disclosed of the apparatus.

In FIG. 2, the top side elevation is disclosed.

In FIG. 3, a top side oblique from a right side elevation is shown.

In FIG. 4, a rearward elevation is shown.

In FIG. 5, a wall assembly is shown with the apparatus shown in use from a front elevation view.

In FIG. 5A, a wall assembly is shown with the apparatus shown in use from a front right side oblique elevation view.

In FIG. 5B, a detail view of FIG. 5A detailing the proximal end of the apparatus in use is shown.

In FIG. 6, a rear elevation view of the wall assembly is shown showing the apparatus in use.

In FIG. 7, a left side frontal oblique view of an embodiment of the apparatus is shown.

In FIG. 8, a frontal elevation of an embodiment of the apparatus is shown.

In FIG. 9, a top side elevation is shown of an embodiment of the apparatus.

In FIG. 10, a rearward elevation of the embodiment of the apparatus is shown.

DETAILED DESCRIPTION OF THE INVENTION

This invention as disclosed in the drawings has the principle use in the construction environment but there exists no limiting language to prevent this invention to be practiced in other fields of use. The invention consists of two main elements, a blocking section and a retention section. This invention is detailed with the use of the invention in the creating of shear panels in new or existing wood framed construction but its use is not limited to only construction industry usage as disclosed by its best mode disclosure by this application.

FIG. 1 details the front view of the apparatus 100 where exterior portion 2 of strap 1 is bounded by proximal end 10 and distal end 9 with top edge 8 and lower edge 8A. Distal end 9 contains header attachment means 28. The strap 1 has two principle functional areas; a blocking section 1B and a header section 1A. The strap is constructed using metallic compounds, usually steel or aluminum. It is foreseen that other materials can be used so long as the structural integrity of the strap is maintained. The thickness or gauge of the strap will directly correlate to the lateral shear force resistance values of the strap as well as the length of the strap as it attaches to the header. FIG. 3 details the attachment means 28 shown in this disclosure as a pattern of nail openings 6, said opening extending from exterior portion 2 through rearward portion 3. Said attachment means is the method through which apparatus 1 is secured to a member that forms the upper header of an opening in a building wall. When an opening is constructed in a wall that is subject to shear forces, blocks and steel straps are used to transfer shear moments at the opening to the vertical diaphragm to attempt to prevent lateral forces from collapsing the wall. FIG. 5 shows such an opening for a window. Construction Codes mandate that openings in horizontal diaphragms with a dimension that is greater than 4 feet shall be constructed with metal ties and blocking. Blocking shall extend not less than the dimension of the opening in the direction of the tie and blocking. Ties shall be attached to blocking in accordance with the manufacturer's instructions but with not less than eight 16d common nails on each side of the header-joist intersection. In this disclosure, attachment means is a series of nail opening pattern 6 through which 16d common nails are inserted, thereby attaching the distal end of the apparatus to the header portion 21 of the opening, as detailed in drawing FIGS. 5 and 5A.

FIG. 2 is an upper view of the apparatus detailing the series of blocks 4 that are attached near the proximal end of apparatus 1, where said blocks are bounded by four horizontal lateral surfaces 12 and two vertical faces 10. Said blocks are constructed of a material that is accepted in the building codes. Current construct practices use lumber, usually poor quality scrap materials that are lying about the construction site, which are of varying quality, causing their shear force resistance value to vary as well. In this apparatus, metal blocks are recommended for ease of manufacturing and attachment to the rearward portion 3 of strap 1.

Said blocks 4 are separated by stud width opening 14 located on the rearward portion 3, which is usually a distance of 1½ inches which is the width of the 2×4 or 2×6 studs that are commonly used in wood construction. This width can be varied for other dimensions of lumber studs. Opposite of inter-stud width opening 14 on external portion 2 exists nail clip 5 and stud nail pattern 5A. The use of nail clip 5 is to facilitate a quick method of securing the apparatus in the opening, where once held in place, allows the installer to properly use the stud nail pattern 5A to attach the apparatus to the stud. At each opening between the existing studs, the blocks are inserted until the proximal end 10 is reached with proximal nail pattern 7 being used to secure the studs. Nail Clip 5 is also located in the proximal nail pattern 7 as seen in FIG. 3. Stud overlap 15 allows for the strap to extend past the last block. In the figures presented with this disclosure, only 2 blocks are being disclosed but this does not limit this disclosure to only a particular number of blocks. Larger openings will require a larger shear load moment resistance which will require more blocks and a longer strap to connect them.

FIG. 5 details the installation of the apparatus in the framing of a window opening. FIG. 5A details that the inter-stud distance 24 is used to determine the lateral horizontal dimension 12 of the block to fit between studs 23. Cripple studs 27 form the connection between the header 21 and top plate 29, while jack studs 26 hold the header 21 in place vertically. King stud 25 provides additional structural security to the assembly between the sole plate 28 an top plate 29. FIG. 5B details stud width 14 firmly encompassing stud 23 and stud width opening 24 is entirely filled with block. Proximal end 10 with stud overlap 15 cover the last stud FIG. 6 is a rearward view of the assembled apparatus with blocks 4 completely occupying the entire inter-stud distance 24. It should be noted that FIG. 5 details that two apparatus are used in securing the opening, one on each side of the opening attaching to the header 29.

An embodiment of the invention is the incorporation of two apparatuses into a single apparatus. Similar to the apparatus disclosed in FIG. 3, FIG. 7 shows an embodiment of the design where a single strap 28 is used incorporating the same blocks 4 spaced apart using the stud with opening 14. Header opening dimension 30 is used to span the opening located along the header of the opening. This embodiment will enable the installer to more quickly secure the opening using only one apparatus that has been specifically designed for the particular opening.

It can be appreciated by those appropriately skilled in the art that changes, modifications or embodiments can be made to this invention without departing from the spirit, principles, theories, ideas or conceptions that have been disclosed in the foregoing. It is herein recognized that the embodiments disclosed by this description of the best mode of practicing this invention, which will be hereafter described in their full breadth in the claims and equivalents thereof.

Claims

1. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms comprising of a

strap portion, where said strap portion comprises of a length of material having an external portion and an interior portion, said strap containing a multiple set of attachment means and an overlap section, and;

a block portion, said block portion comprising of at least one block protruding from and attached to said interior portion of said strap.

2. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 1 where said strap portion further comprises a

a blocking section, said blocking section containing said blocks, and;

a header section containing said multiple sets of attachment means.

3. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 1 where said lateral portion of said blocks is similar to the inter-stud width opening of adjacent studs.

4. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 3 where said apparatus contains 2 blocks.

5. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 3 where said apparatus contains more than 2 blocks.

6. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 1 where said attachment means consists of at least one stud nailing pattern and a header nail pattern

7. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 6 where said attachment means consists of at least one stud nailing pattern and a header nailing pattern, where said nailing pattern further comprises at least one nailing clip

8. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms comprising of a

strap portion, where said strap portion comprises of a length of material having an external portion and an interior portion, said strap containing a multiple set of attachment means and at least one overlap section, and;

at least one block portion, said block portion comprising of at least one block protruding from and attached to said interior portion of said strap.

9. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 8 where said strap portion further comprises a

at least one blocking section, said blocking section containing said blocks, and;

a header section containing said multiple sets of attachment means.

10. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 8 where said lateral portion of said blocks is similar to the inter-stud width opening of adjacent studs.

11. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 10 where said apparatus contains 2 blocks.

12. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 10 where said apparatus contains more than 2 blocks.

13. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 8 where said attachment means consists of at least one stud nailing pattern and a header nail pattern.

14. An improved mechanical apparatus for resisting lateral loads in shear panel diaphragms as in claim 13 where said attachment means consists of at least one stud nailing pattern and a header nailing pattern, where said nailing pattern further comprises at least one nailing clip.