LOW PRY SEISMIC FITTING

Abstract

Applicant has disclosed a seismic fitting, and related method, to attach a cable to a structure (e.g., a concrete ceiling, wall or beam of a commercial building). In the preferred “apparatus” embodiment, the seismic fitting, when anchored, comprises: a base with a substantially circular footprint; a substantially circular inner channel, in the base, housing a midsection of cable (preferably wire rope); at least two cable exits in the inner channel, wherein the cable exits are chamfered to prevent and radially equidistant from one another; and a fastener (e.g., a concrete anchor), extending through the entire base, and having one end anchored in concrete; wherein opposite ends of the cable extend beyond the channel and fitting.

Description

RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application Ser. N. 62/311,592, entitled “LOW PRY SEISMIC FITTING,” filed Mar. 22, 2016. Applicant incorporates that prior application by reference in its entirety.

FIELD OF INVENTION

This invention relates to seismic fittings.

BACKGROUND OF INVENTION

Seismic retrofitting (a.k.a. seismic fitting) is typically considered “ . . . the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with our recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codes in the late 1960s for developed countries (US, Japan etc.) and late 1970s for many other parts of the world (Turkey, China etc.), many structures were designed without adequate detailing and reinforcement for seismic protection. In view of the imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world—such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines.” Wikipedia, https://en.wikipedia.org/wiki/Seismic_retrofit, January 2017.

Retrofit techniques are applicable for various natural hazards such as earthquakes, tropical cyclones, tornadoes, and severe winds from thunderstorms.

It is the primary object of this invention to provide an economical seismic fitting to attach cable, e.g., wire rope, to a structure within the lowest allowable limits of prying on the fastener for the fitting.

It is a more specific object to fasten such a low-pry seismic fitting to a commercial structure composed of steel, concrete, wood, or other building material in a manner that will not damage or weaken the cable, captured by the fitting, but will provide a dampening effect and maximum resistance to cable failure under seismic load conditions.

It is yet another object, commensurate with the above-listed objects, to provide a durable seismic fitting which evenly distributes the load on a cable during seismic loads.

It is still another object to allow for installation of the seismic fitting on site.

SUMMARY OF INVENTION

Applicant has disclosed a Low Pry Fitting (“LPF”) which is specifically designed to reduce the prying effect on the fastener. The inventive LPF is a one-piece seismic fitting used to attach cable (e.g., wire rope) to a structure or component of that structure. The fitting does not damage or weaken the cable even when seismic loads push the certified cable to the cable's breaking strength during natural hazards or forces such as earthquakes, tropical cyclones, tornadoes, and severe winds from thunderstorms.

In the preferred “apparatus” embodiment, the LPF comprises: a substantially round, low pry, one-piece device with a raised inner channel provided for the cable; two chamfered exits from the channel for the cable located on the centerline of the fastener; and an attachment hole for attaching the LPF to the structure with a suitable fastener, such as a concrete anchor. The channel has an open bottom. When anchored to a structure, the fitting captures a midsection of the cable with cable end portions extending beyond the fitting.

The LPF is particularly suited for use in concrete structures (e.g., concrete ceilings, walls or beams in commercial buildings) using concrete anchors as the fitting reduces the prying effect on the concrete anchor to minimal levels specified in NFPA-13.

DESCRIPTION OF DRAWINGS

The above and other objects of the current invention will become more readily understood when the following text is read in conjunction with the accompanying drawings, in which:

FIG. 1 is a side plan view of Applicant's preferred LPF anchored in a concrete structure (e.g., the illustrated first ceiling in an office building) with portions of the concrete, LPF and a cable broken away;

FIG. 2A is a front perspective view of the LPF;

FIG. 2B is a back perspective view of the LPF;

FIG. 2C is an enlarged view of an encircled cable exit shown in FIG. 2A.

FIG. 3 is a cross-sectional view of the LPF showing both cable exits;

FIG. 4 is a top perspective view of the LPF, anchored in the concrete structure, with a cable (here, e.g., wire rope) running through the LPF.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS

Applicant has disclosed a Low Pry Fitting (“LPF”) which can be installed onsite in an economical manner. This LPF is specifically designed to reduce the prying effect on a fastener in concrete applications (e.g., concrete ceilings, walls or beams in a commercial building, such as an office building or a parking garage) when used with a cable (wire rope) restraint system to brace against seismic loads.

As shown in FIGS. 1-4, the preferred LPF 100 comprises: a base 102 having a substantially circular outer perimeter; a substantially circular inner channel 104 (see FIGS. 2A, 2B), in the base 102, designed to house a midsection of a cable 106 (e.g., the illustrated wire rope); two exits 108a, 108b (see FIGS. 2A, 2B, 2C) from the channel 104 for the cable 106, wherein the exits 108a, 108b are located on a centerline of a fastener 112 (e.g., the illustrated concrete wedge anchor); and an attachment hole or throughbore 114 substantially perpendicular to, and extending through, the base 102, for attachment of the LPF 100 to a structure 116 (e.g., the illustrated concrete ceiling of an office building) by the fastener 112.

The Merriam-Webster dictionary online (www.merriam-webster.com) defines centerline as “a real or imaginary line that is equidistant from the surface or sides of something.” As used in this application, the phrase “centerline of the fastener” is defined as an imaginary line equidistant from the “side” (not top or bottom) surface of the fastener 112.

As used herein, the term “structure” means something constructed or built of steel, concrete, wood, or other building material.

Chamfered edges 107a, 107b at the exits 108a, 108b of the fitting 100 prevent damage to the outer fibers of the cable 106 (e.g., the wire rope) when under tension. The cable channel 104 provides a positive entrapment of a midsection of the cable 106 when the LPF is attached to a structure 116 (see FIGS. 1, 4). Cable end portions 118a, 118b extend beyond the cable exits 108a, 108b and beyond the fitting 100.

Exits 108a, 108b are substantially the same and radially equidistant from each other. Thus, the LPF 100 only has to be rotated less than 180 degrees prior to inserting the cable 106 during onsite installation of the cabling and LPF. A quick peek through inspection hole 120, in the base 102, can insure the cable 106 is placed in the correct position within the channel 104.

As best seen in FIGS. 2A and 4, the preferred base 102 is flat except for the raised inner channel 104. That channel 104, which preferably has an open bottom, is adjacent the outer perimeter of base 102.

FIG. 1 illustrates the preferred fastener 112 being an expansion type concrete fastener (here, a wedge anchor) embedded in a concrete structure 116.

As explained at https://www.confast.com/articles/how-to-install-concrete-fasteners.aspx, the steps for installing a wedge anchor in cured concrete is:

• • 1. Drill hole into the concrete using a carbide tipped bit that meets ANSI standards. Bit size=anchor diameter when working with wedge anchors. Drill a hole ½″ deeper than the anchor will penetrate into the concrete making sure that the minimum embedment requirements are met. The hole can be drilled while the fixture is in place. It is important to make sure that the bit diameter being used will fit through the hole in the fixture.
  • 2. Clean out the hole using a wire brush, compressed air, vacuum, blow out bulb or another method.
  • 3. Put the nut and washer onto the wedge anchor and make sure that the nut is on the last threads (this will protect the threads from damage when the wedge anchor is hammered into the hole in the concrete).
  • 4. Insert the wedge anchor through the fixture's hole and into the hole in the base material. This should be a very tight fit—use a hammer to complete the installation until the nut and washer are tight against the fixture. It is important that the threads go below the surface of either the base material or the fixture.
  • 5. Turn the nut clockwise, until finger tight.
  • 6. Using a wrench, turn the nut 3-4 times until snug.

For concrete applications, it is simplest to place the fastener 112 before pouring of the concrete.

FIG. 4 shows the LPF 100, anchored to the concrete structure 116 (e.g., the illustrated first floor's ceiling 116 in an office building), with wire rope ends 118a, 118b. Each cable (wire rope) end can be used to brace structural components or devices (e.g., fire sprinkler systems, HVAC systems and plumbing pipes) in any suitable manner. For example, lateral bracing, longitudinal bracing or 4-way bracing could be used to brace a pipe (not shown).

Base 102 has a circular footprint, when anchored by fastener 112 (see FIGS. 1, 4). Cable 106 is captured in channel 104 when the LPF 100 is anchored to the structure (here, the illustrated concrete ceiling).

By allowing the load force to be distributed equally on both sides of the installed fastener 112, due to the alignment of the pressure points of the cable (wire rope) 106 with the centerline of the fastener 112, the prying effect on the fastener 112 is lessened during seismic events, cyclones, tornadoes, or severe winds from thunderstorms.

Using the LPF 100 and certified cable 106 (preferably wire rope) will allow for the code compliant tensioned sway control bracing of structural components, with the minimal prying effect applied to the fastener 112.

The LPF 100 is used to achieve compliance with various building codes and standards including, but not limited to, NFPA-13 and ASCE-7 for bracing of structural components or devices to resist damage due to seismic activity when using cable (wire rope) as the bracing element in a tension only environment.

For example, NFPA-13 describes a preferred order of where to fasten a seismic fitting in a commercial building: the ceiling, a wall, and a beam. That is the same preferred order for the LPF 100.

The LPF 100 is designed primarily to be anchored in a concrete ceiling (e.g., ceiling 116). When the LPF is in use, one cable end portion (e.g., 118b) is connected to the other cable portion (e.g., 118a) by a crimped sleeve 122 (see FIG. 4).

The LPF 100 is also applicable to resist damage due to other natural hazards such as tropical cyclones, tornadoes, and severe winds from thunderstorms.

The LPF's reduction in the prying effect on the fastener 112 would also apply to the prying forces experienced in steel, wood, or other building materials. The LPF 100 would allow for smaller diameter fasteners to be used in those applications due to the low prying effect that these fittings provide.

Applicant's invention can also be thought of in method terms. In broadest language, the method comprises:

• • a. housing a midsection of cable within a substantially circular inner channel of a seismic fitting;
    • i. wherein the channel has an open bottom;
  • b. anchoring the seismic fitting to a structure; and
  • c. whereby the midsection of cable is captured between the structure and the open-bottom inner channel.

A narrower method comprises:

• • a. anchoring a seismic fitting to a structure (e.g., composed of steel, concrete, wood, or other building material) via an anchor extending perpendicular to the fitting, and entirely through a central throughbore of the fitting, with opposite ends of the anchor extending beyond the fitting;
  • b. wherein the seismic fitting comprises:
    • i. a base with a substantially circular footprint;
    • ii. the base has a front and a back;
    • iii. a substantially circular inner channel in the base and adjacent an outer perimeter of the base; and
    • iv. at least two cable exits from the inner channel, wherein the at least two cable exits are radially equidistant from each other, and wherein the at least two cable exits are located on a centerline of a concrete anchor; and
  • c. housing a midsection of cable, within the channel, with two opposite end portions of the cable extending beyond the cable exits and the fitting.

It should be understood that obvious structural modifications can be made without departing from the spirit or scope of the invention. For example, though perhaps not as secure: a sleeve anchor—used in concrete, brick or block—could be utilized as fastener 112. Accordingly, reference should be made primarily to the following claims rather than the foregoing specification to understand the scope of the invention.

Claims

1. A seismic fitting comprising:

a. a base, of the fitting, having a substantially circular outer perimeter;

b. the base has a front and a back;

c. a substantially circular inner channel, in the base, adapted in size and shape to house a midsection of wire rope;

d. two wire rope exits from the inner channel,

e. a throughbore substantially perpendicular to, and extending through the center of, the base; and

f. wherein the throughbore is adapted in size and shape for a concrete anchor to extend though the entire throughbore.

2. The seismic fitting of claim 1 further comprising chamfered edges at the exits to prevent damage to the wire rope when the wire rope cable is under tension.

3. The seismic fitting of claim 1 wherein the concrete anchor is a wedge anchor.

4. The seismic fitting of claim 1 wherein the two exits are 180° apart in the channel.

5. An apparatus comprising:

a. a seismic fitting comprising: i. a base with a substantially circular footprint; ii. the base has a front and a back; iii. a substantially circular channel, in the base, wherein the channel houses a midsection of a cable; iv. two cable exits in the inner channel, wherein the cable exits are radially spaced apart by 180°; and v. a throughbore perpendicular to, and extending through the center of, the base;

b. a concrete anchor, extending through the entire throughbore, and having one end anchored in concrete;

c. the concrete anchor is secured to the fitting; and

d. wherein two end portions of the cable extend beyond the cable exits and the fitting.

6. The seismic fitting of claim 5 further comprising chamfered edges at the cable exits to prevent damage to the cable when the cable is under tension.

7. The seismic fitting of claim 5 wherein the cable comprises a wire rope.

8. The seismic fitting of claim 5 wherein the concrete anchor is a wedge anchor.

9. A method of securing a cable to a structure, the method comprising:

a. anchoring a seismic fitting to a structure via an anchor extending perpendicular to the fitting and entirely through a central throughbore of the fitting with opposite ends of the anchor extending beyond the fitting;

b. wherein the seismic fitting comprises: i. a base with a substantially circular outer perimeter; ii. the base has a front and a back; iii. a substantially circular channel in the base and adjacent the perimeter; and iv. at least two cable exits from the inner channel, wherein the at least two cable exits are radially equidistant from each other, and wherein the at least two cable exits are located on a centerline of the anchor; and

c. housing a midsection of cable, within the channel, with two end portions of the cable extending beyond the cable exits and the fitting.

10. The method of claim 9 wherein the cable comprises a wire rope.

11. The method of claim 9 wherein the at least two cable exits have chamfered edges to prevent damage to the wire rope when the wire rope is under tension.

12. The method of claim 9 wherein the anchor is a concrete wedge anchor and the structure is concrete.

13. The method of claim 9 wherein the at least two exits are radially equidistant in the channel.

14. A method comprising:

a. housing a midsection of cable within a substantially circular inner channel of a seismic fitting; i. wherein the channel has an open bottom;

b. anchoring the seismic fitting to a structure; and

c. whereby the midsection of cable is captured between the structure and the open-bottom inner channel.