Threaded rod wind and seismic resistance system

Abstract

Wood framed walls of buildings are strengthened against destructive wind and seismic forces by a threaded hold-down rod attached to the structure top plate and anchored to the building foundation. The foundation structure may be concrete or other floor joist or the like. The threaded rod is normally used in a system that attaches at top and bottom of studs at approximately every fourth or fifth stud along all load-bearing walls. The threaded rod system comprises two sections of threaded rod connected to the structure by way of a nut and washer at the top plate and embedded in the foundation at the bottom. A short section of threaded rod is embedded in the foundation and a coupling nut connects the short section to the remaining threaded rod section near the bottom plate. The short section may be manufactured of galvanized steel or stainless steel to avoid corrosion where fastened to a pressure treated bottom plate. In an alternate embodiment, an elongated wire bolt rod can be attached to the foundation and directly to a roof truss and ceiling plate. The described system can be installed during initial construction of a structure or retrofit into existing structures.

Description

CROSS REFERENCE TO RELATED APPLICATION

This Application claims the benefit of U.S. Provisional Application, Ser. No. 60/546,633 entitled Threaded Rod Wind and Seismic Resistance System, filed with the U.S. Patent and Trademark Office on Feb. 21, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to wood frame building structures, and more particularly to structures exposed to extreme wind and/or seismic conditions where building codes dictate that these structures be protected against structural failure and/or to save lives of occupants. In particular, the present invention relates to a hold-down system for anchoring the structure of a wood frame building to resist uplift forces encountered during a high wind or seismic situation. The present invention also relates to a system of threaded rods that provides additional reinforcements for an existing structure.

2. Background of the Prior Art

It is well known what high winds can do to a building, particularly to a wood frame construction low-rise structure. Generally, uplift forces tending to lift the roof off the structure or the entire structure off its foundation cause much of the damage sustained by the building.

Wood structures predominate in residential and light commercial construction, and when wood framing is employed, the structure must be protected from upward, shear and overturning loads developed by either wind or seismic activity, which differs with geographical location and is enforced by different building codes for these areas. For example, the Bahamas and Florida coastline, including the Florida Keys are situated in the pathway of the yearly Caribbean hurricane travel course and as such, encounter hurricanes and/or tornadoes from time to time.

In the case of upward loads, the building is generally tied to the foundation using a variety of steel connectors that tie the bottom plate to the foundation, wall studs to bottom plates, top plate to wall studs, floors to walls, and roof to walls. Typically, for uplift, connectors are attached to every stud (16″ O.C.), or at least every other stud (32″ O.C.). Shear and overturning loads are resisted by a combination of heavy-duty steel connectors, (either bolted to, or embedded in, the foundation, and nailed or bolted to the wood frame), and an approved structural sheathing material nailed directly to the exterior of the structure is used to create what is referred to as a “shear wall”. The size and number of such steel connectors vary depending on the severity of the wind and/or seismic conditions expected in the locality of the building, and the building's geometry.

In the current method used in the United States, such connectors are installed during the foundation and framing stages of construction. Laborers hired by the framing contractor generally install the connectors and sheathing. Correct size, location and number of fasteners (nails, screws, or bolts), are critical to the required load. Commonly, these laborers are inexperienced which frequently results in improper or inadequate installation. In all structures, the locations of most connectors mandate their installation during the framing stage due to related building components being placed at the same time. This process slows the foundation and framing stages of construction, which in turn increases labor costs. In addition, existing structures without having appropriate connectors in place are at risk of destruction should a hurricane or earthquake occur.

From the foregoing, it is apparent that there is a critical need for a structural tie-down system that provides for uplift, shear and overturning loads that is cost effective and easy to install and that can be installed after the foundation and framing stages of the building are complete.

The various features of novelty that characterize the invention will be pointed out with particularity in the claims of this application.

SUMMARY OF THE INVENTION

The present invention provides a solution to the above problem by reinforcing and anchoring the structure to the ground, wherein a hold down force is applied to the wall studs to counter the uplift and horizontal forces generated by high winds. The present invention can be incorporated during initial construction of the structure or retrofit into preexisting structures.

It is an object of the present invention to provide a threaded rod anchor system for a structure of a wood frame building that reinforces the structure against damage in a high wind situation, such as a hurricane.

It is a further object of the present invention to enable installation of a threaded rod anchor system after the foundation is set, without prior embedding anchor bolts. A related object is to enable installation of a threaded rod anchor system after the roof, wall framing, and exterior sheathing are in place.

It is another object of the present invention to provide an anchor system for a frame construction building that provides a downward force around the periphery of the structure, thereby to better resist any upward lift imparted to the walls and roof by high winds. It is still another object of the present invention to provide an anchor system for a low-rise, wood frame building that can be easily installed in preexisting structures. A related object is to enable increased uplift resistance in pre-existing structures with minimum invasion of wall members. A further related object is to increase value in structures existing in high wind and seismic zones.

It is another object of the present invention to provide an anchor system for a wood frame building that provides reinforcement to the walls and roof structure, thereby providing greater resistance to damage during high wind conditions. A related object is to increase public safety in structures existing in high wind and seismic zones.

It is a further object of the present invention to eliminate the need for hurricane clips and straps to be installed at top and bottom plates in the construction of a wood frame building.

It is yet another object of the present invention to enable cost effective construction of wood frame structures while meeting all Building Code requirements. A related object is to provide an anchor system for a building that complies with the recommendation of all major building codes.

This invention relates to a novel method of bracing a wood framed building, e.g., a residential dwelling, having a structure including a foundation upon which rests a plurality of parallel vertical studs separating horizontal bottom plates from horizontal ceiling plates. The structure is reinforced against the destructive forces of the atmosphere and of seismic origin by a system of threaded rods between vertical studs and between bottom plates and ceiling plates, at much greater spacing than 32″ O.C. In a preferred embodiment, a vertical connection is made between such horizontal bottom plate and horizontal ceiling plate, and the concrete foundation. The system comprises two sections of threaded rod connected to the structure by way of a nut and washer at the top plate and embedded in the foundation at the bottom. A short section of threaded rod is embedded in the foundation and a coupling nut connects the short section to the remaining threaded rod section near the bottom plate.

Recent changes to EPA regulations require that a more metal corrosive treatment be used in pressure treated wood. The treatments that are currently used have been banned. Therefore, in frame construction where pressure treated wood comes into contact with metal (i.e. threaded rods) it is necessary to use a corrosive resistant material, such as galvanized or stainless steel. It is obvious that to place full-length rods from the foundation slab to the top plate will be extremely expensive and drive costs up. Accordingly, the present invention is vital to reduce cost and prevent corrosion by using a short section of galvanized or stainless steel rod of a length that will be long enough to establish adequate embedment depth into the concrete foundation, typically 6 inches, and to pass through the pressure treated bottom wall plate approximately 3 inches. After that, the short section of rod can connect to a standard, non-coated rod with a coupling and then on through to the top plate.

The threaded rod system disclosed herein offers more body, more strength, and more durability to the purchasing public. Such threaded rod system may be made from different combination of sizes of the smaller diameter, upper longer rod and the short larger diameter rod at the bottom to fit many framing applications and strength requirements. Such threaded rod anchor system creates a solid attachment between the foundation and the ceiling top plate. This simple invention enables a threaded rod anchor system that can be easier to install and more reasonably priced and that, in fact, can be made or put in place by any skilled or semi-skilled person.

The various features of novelty that characterize the invention will be pointed out with particularity in the claims of this application.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features, aspects, and advantages of the present invention are considered in more detail, in relation to the following description of embodiments thereof shown in the accompanying drawings, in which:

FIG. 1 is an elevational view of a typical load bearing wall section employing the present invention;

FIG. 2 shows an illustration of one embodiment of the present invention;

FIG. 3 shows an enlarged portion of FIG. 2 illustrating an embodiment of the present invention as connected to the top plate;

FIG. 4 shows an enlarged portion of FIG. 2 illustrating an embodiment of the present invention as connected to the bottom plate; and

FIG. 5 is a cross sectional view of a method of embedding a threaded rod in a foundation according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention summarized above and defined by the enumerated claims may be better understood by referring to the following description, which should be read in conjunction with the accompanying drawings in which like reference numbers are used for like parts. This description of an embodiment, set out below to enable one to build and use an implementation of the invention, is not intended to limit the enumerated claims, but to serve as a particular example thereof. Those skilled in the art should appreciate that they may readily use the conception and specific embodiments disclosed as a basis for modifying or designing other methods and systems for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent assemblies do not depart from the spirit and scope of the invention in its broadest form.

FIG. 1 shows a typical load bearing wall section employing a threaded rod system according to the present invention, indicated generally as 10. Wall studs 13 may be single or doubled and serve to connect ceiling plate 16 with bottom plate 19. Such bottom plate 19 may be manufactured of pressure treated lumber. In a typical construction, the threaded rod system 10, would be used on each side of all load bearing exterior corners, within 12-inches of each corner and on each side of all openings 6-feet or greater. Such system would also be used at an average of 6-feet on center intervals in between and along bearing walls having uplift loads. This corresponds to approximately every fourth or fifth stud along such load-bearing wall. In an alternate embodiment, a wire bolt system can be used in place of the full-length threaded rod.

Referring to FIG. 2, a threaded rod system 10 is illustrated, having an elongated threaded rod 21 connected at its top end to top plate 16 and connected at its bottom end to a coupler 25. The threaded rod system 10 is situated between wall studs 13 and within the inner wall 22 and outer wall 23. Threaded rod 21 may comprise a ½-inch, ⅜-inch, or ¼-inch steel rod having threads along its entire length. In an alternate embodiment, threaded rod 21 can be replaced by an appropriately constructed wire bolt having a threaded portion at each end.

As further illustrated in FIG. 3, an aperture is created through top plate 16 to enable threaded rod 21 to pass therethrough. Top plate 16 may consist of double plates 26, 27 as would be apparent to those skilled in the art. Threaded rod 21 is passed through the aperture and secured by a suitable washer 28 and nut 30 above the top plate 27. Nut 30 has internal threads to engage threaded rod 21.

Threaded rod 21 is connected at its bottom end to a coupler 25, as shown in FIG. 4. Coupler 25 has an internally threaded female fitting on both ends. In one embodiment, coupler 25 is sized and configured to receive a threaded rod of the same size on each end. In another embodiment, coupler 25 comprises a reducer coupling wherein coupler 25 is sized and configured to receive a threaded rod of one size on a first end and of a second size on the remaining end. For example, coupler 25 may be sized to receive a ⅝-inch stubby rod 36 on one end and either a ½-inch, ⅜-inch, or ¼-inch threaded rod 21 on the other end. In another application, coupler 25 may be sized to receive a ½-inch stubby rod 36 on one end and either a ⅜-inch or ¼-inch threaded rod 21 on the other end

As further illustrated in FIG. 4, threaded rod system 10 further comprises a stubby threaded rod 36 embedded in the building foundation, as described below. An aperture 39 is created through bottom plate 19 to enable stubby rod 36 to pass therethrough. Stubby rod 36 may be secured by a suitable washer 41 and nut 43 above bottom plate 19. To conform to present EPA requirements for avoiding corrosion, if bottom plate 19 comprises pressure treated lumber such stubby rod 36 should be zinc coated or constructed of galvanized steel or stainless steel. Stubby rod 36 is connected to coupler 25 on such coupler's bottom end. Stubby rod 36 may comprise a ⅝-inch, ½-inch, ⅜-inch, or ¼-inch steel rod having threads along its entire length. In a preferred embodiment, stubby rod 36 is of a larger size than threaded rod 21.

Referring to FIG. 5, stubby rod 36 is embedded in foundation 45. Preferably, the foundation 45 is poured and bottom plate 19 and foundation 45 are subsequently drilled to form a socket 55 to receive stubby rod 36. Socket 55 is partially filled with a suitable adhesive 59, for example, epoxy, polymers, expanding cements, etc. It is understood that foundation other than slab foundations are within the purview of this invention such as a basement or stem wall which may have a wood floor system between the bottom plate and the embedment into concrete. When using a threaded rod as the stubby rod 36, such rod should be embedded at least 6-inches into foundation 45 and should be long enough to extend approximately 3 inches above bottom plate 19.

In an alternate embodiment, stubby rod 36 may be held in socket 55 by a compression anchor fitting embedded in foundation 45.

The invention has been described with references to a preferred embodiment. While specific values, relationships, materials and steps have been set forth for purposes of describing concepts of the invention, it will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the basic concepts and operating principles of the invention as broadly described. It should be recognized that, in the light of the above teachings, those skilled in the art could modify those specifics without departing from the invention taught herein. Having now fully set forth the preferred embodiments and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It is intended to include all such modifications, alternatives and other embodiments insofar as they come within the scope of the appended claims or equivalents thereof. It should be understood, therefore, that the invention may be practiced otherwise than as specifically set forth herein. Consequently, the present embodiments are to be considered in all respects as illustrative and not restrictive.

Claims

1. A system for bracing a wood frame structure, comprising:

an elongated threaded rod attached to a top plate of said wood frame structure;

a stubby threaded rod attached to a foundation of said wood frame structure; and

a coupler joining said elongated threaded rod and said stubby threaded rod, wherein said stubby threaded rod passes through a bottom plate of said wood frame structure and is embedded in said foundation.

2. The system of claim 1, further comprising:

a nut and washer to attach said elongated threaded rod to said top plate.

3. The system of claim 1, wherein the system is placed within a wall of said wood frame structure.

4. The system of claim 1, wherein said elongated threaded rod is the same diameter as said stubby threaded rod.

5. The system of claim 2, wherein said coupler has internally threaded female fittings on both ends and said coupling is sized and configured to receive a threaded rod of the same size on each end.

6. The system of claim 1, wherein said elongated threaded rod is a smaller diameter than said stubby threaded rod.

7. The system of claim 6, wherein said coupler has internally threaded female fittings on both ends and said coupling is sized and configured to receive a threaded rod of one size on a first end and a treaded rod of a second same size on a second end.

7. The system of claim 1, further comprising:

a nut and washer to attach said elongated threaded rod at said bottom plate.

8. The system of claim 1, wherein said elongated threaded rod is replaced by a wire bolt having a threaded connection of each end.

9. The system of claim 1, wherein said elongated threaded rod comprises a steel rod having a diameter selected from the group consisting of:

½-inch;

⅜-inch; and

¼-inch.

10. The system of claim 1, wherein said stubby threaded rod comprises a steel rod having a diameter selected from the group consisting of:

⅝-inch;

½-inch;

⅜-inch; and

¼-inch.

11. The system of claim 1, wherein said stubby threaded rod comprises stainless steel.

12. The system of claim 1, wherein said stubby threaded rod comprises galvanized steel.

13. The system of claim 1, wherein said stubby threaded rod comprises zinc coated steel.

14. A method of strengthening a wood frame building structure to resist high wind and seismic conditions, such method comprising the steps of:

a. forming a socket in a foundation of such structure through a floor plate of such building frame;

b. attaching a first section of threaded rod to the foundation by inserting said first section of threaded rod into such socket and fastening such first section of threaded rod to the foundation;

c. forming an elongated tunnel through a ceiling plate of such building frame;

d. attaching a second section of threaded rod to the ceiling plate by inserting said second section of threaded rod into such elongated tunnel and fastening such second section of threaded rod to the ceiling plate; and

e. attaching said first section of threaded rod to said second section of threaded rod by a coupler.

15. The method according to claim 14, wherein the diameter of said first section of threaded rod is the same as the diameter of said second section of threaded rod.

16. The method according to claim 14, wherein the diameter of said first section of threaded rod is greater than the diameter of said second section of threaded rod.

17. The method according to claim 16, wherein said coupler comprises a reducing coupler.

18. The method according to claim 14, wherein said first section of threaded rod is attached to said foundation by means of said threaded rod being embedded in the foundation and sealed in place by a suitable adhesive.

19. The method according to claim 14, wherein said first section of threaded rod is attached to said foundation by means of a compression anchor embedded in the foundation.

20. The method according to claim 14, wherein said first section of threaded rod comprises steel selected from the group consisting of:

stainless steel;

galvanized steel; and

zinc coated steel.