System and Method for Structural Restraint Against Seismic and Storm Damage

Abstract

A system for structural restraint of structures against seismic and storm damage comprises a plurality of structural framing components; a plurality of structural sheathing components; a plurality of structural fasteners; one or more structural foundations; and a structural bonding agent applied to the interior and exterior to prevent failure of structural fasteners.

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to construction systems. In particular, the present invention relates to a restraint system for reinforcement of buildings against seismic and storm damage.

BACKGROUND OF THE INVENTION

Much of the world's population is located along seismic fault lines or in the paths of powerful storms such as hurricanes, monsoons, floods and tornadoes. The buildings in such areas are at risk of structural damage from seismic and storm events. As these population centers grow, the risk of loss of life and damage to structures will only increase.

During powerful seismic and storm events, prior art wood or light gauge steel frame construction techniques do not adequately hold the structural building components together. Although such framed structures are among the safest currently available, powerful seismic and storm events may result in the failure of their structural integrity. The primary reason for structural failure is the inability of the structural fasteners to keep the structural sheathing firmly attached to the structural framing. As structural fasteners primarily are designed to be static devices, they are likely to fail when subjected to dynamic forces.

Many jurisdictions are seeking ways to mitigate the effects of these powerful seismic and storm events through the upgrading of building codes. To date, nothing has been available to solve the problems associated with these events. Governments, as well as construction, insurance and forest industries and the general population, all have a great deal to benefit from a solution to these damaging effects.

As powerful seismic and storm events act on a structure, the three dimensional dynamic forces compromise the structural fasteners, causing them to work their way loose or out of the members in which they are embedded or, if they remain in place, they may tear their way through the structural sheathing or simply break off. The result is the weakening or complete loss of structural integrity of the building as the structural forces no longer are able to be transferred safely down to the structural foundations.

During powerful seismic and storm events failure points occur primarily along structural fastener strips of structural sheathing. These failure points may be at corners, at intersections, around door, window and other openings, at vertical joints, and along horizontal joints at floor and ceiling edges.

Presently there are no systems or structural fasteners which can prevent these failures. Existing prior art solutions use a form of building restraint consisting of a complex engineered system of steel rods, anchors, plates and straps requiring extensive notching, drilling and additional structural reinforcement. Installation of such a system may interfere significantly with construction schedules in that electrical, plumbing and other sub-trades will have their work suspended while the required building modifications are carried out. This form of restraint system fails to provide a solution to the problem of structural fasteners breaking off or pulling loose, out or through the structural sheathing, putting at risk the structural integrity of the structure.

The restraint system of the present invention provides a solution which maintains the integrity of the structural fasteners. This results in the structural sheathing remaining firmly attached to the structural framing and the structural foundations. The integrity of the entire structure is maintained and the structural loads are able to be transferred safely down to the structural foundation.

SUMMARY OF THE INVENTION

There is provided a system for structural restraint of structures against seismic and storm damage, the system comprising a plurality of structural framing components; a plurality of structural sheathing components; a plurality of structural fasteners; one or more structural foundations; and a structural bonding agent.

The structural bonding agent may be a thermoset elastomer having a tensile strength of at least 15 MPa (2000 psi) and may have an elastomeric flexural strength of at least 300%. The structural bonding agent may remain flexible to temperatures as low as −40° C. (−40° F.).

The structural bonding agent may be a spray foam insulation having a tensile strength of at least 0.35 MPa (50 psi) and an elastomeric flexural strength of at least 300%, and may remain flexible to temperatures as low as −40° C. (−40° F.).

There is further provided the use of a structural bonding agent to reinforce building structures against seismic and storm damage by preventing egress of structural fasteners from structural building components. The structural bonding agent used may be a thermoset elastomer, or a spray foam insulation.

The invention further comprises a method of reinforcing a structure against seismic or storm damage comprising the steps of framing a desired structure; applying a structural flexible bonding agent over structural fasteners at selected locations of the framed structure to achieve a desired thickness. The bonding agent may be injected into a structural cavity or applied by spraying. The flexible bonding agent may be applied to an area of between 100 mm (4″) and 255 mm (10″) wide centered over the joint between structural components.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the preferred embodiments is provided by way of example only and with reference to the following drawings, in which:

FIGS. 1A and 1B are cross-sectional views of two exterior walls of a building extending between structural foundation wall and roof truss, one (1B) of which depicts door and window openings, according to one embodiment of the present invention;

FIG. 2 is a cross-sectional view of the assembly of a wall stud, floor joist and structural foundation wall, according to one embodiment of the present invention;

FIG. 3 is a cross-sectional view of an assembly of a wall stud, floor joist and structural foundation wall including a door opening, according to one embodiment of the present invention;

FIG. 4 is a cross-sectional view of an assembly of a lower level wall stud, floor joist, and upper level wall stud above a door opening, according to one embodiment of the present invention;

FIG. 5 is a cross-sectional view of an assembly of a lower level wall stud, floor joist, and upper level wall stud, according to one embodiment of the present invention;

FIG. 6 is a cross-sectional view of a wall stud adjacent a window opening, according to one embodiment of the present invention;

FIG. 7 is a cross-sectional view of a wall stud and roof truss, according to one embodiment of the present invention;

FIG. 8 is a cross-sectional view of a wall stud and roof truss above a window opening, according to one embodiment of the present invention;

FIG. 9 is a front plan view of sections A, B and C of a structural wall, according to one embodiment of the present invention;

FIGS. 10A, 10B, and 10C are cross sectional views of corresponding wall sections A, B, and C of FIG. 9, according to one embodiment of the present invention;

FIG. 11A depicts a top view cross section of a wall configuration consisting of a 90 degree framed exterior corner;

FIG. 11B depicts a top view cross section of a wall configuration consisting of a 90 degree framed exterior corner, two 45 degree framed exterior corners and a 90 degree framed interior corner;

FIG. 11C depicts a top view cross section of a wall configuration consisting of two typical 45 degree framed interior corners; according to one embodiment of the present invention; and

FIG. 12 depicts a structural wall corner showing use of structural flexible spray foam insulation.

In the drawings, one embodiment of the invention is illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention.

DETAILED DESCRIPTION OF THE INVENTION

There is provided a structural restraint system to maintain building structural integrity during powerful seismic and storm events. The restraint system of the present invention reduces or eliminates structural fastener failure, whether through breakage, loosening, detachment, or rupture through the structural components they are meant to secure.

The restraint system of the present invention comprises five building components. These five structural building components are framing, sheathing, fasteners, a foundation, and a flexible bonding agent.

The framing may be manufactured of wood, steel, concrete, composite materials and combinations thereof Framing components may include studs, posts, plates, joists, rafters, beams, lintels, built up assemblies, trusses and monolithic concrete walls and floors.

The sheathing may be manufactured of wood, plank, plywood, oriented strand board (OSB), wafer board, composite boards, cement boards, fiberglass, polymer products and other structural membranes for walls, roofs and floors;

Each fastener may be a hardware device that mechanically joins two or more structural components together, for example, nails, staples, screws, and bolt assemblies.

The foundation may be constructed of concrete, masonry, treated wood, or other approved material

A suitable flexible bonding agent may be a spray-applied structural flexible elastomer, for example polyurea or equivalent, or a spray-applied flexible structural foam insulation, for example polyurethane or equivalent. The flexible bonding agent is applied to corresponding interior and exterior portions of the structure. The flexible bonding agent ideally should achieve rapid thermosetting, have fast reactivity, be relatively insensitive to moisture, and be fully curable in high humidity, cold or moist substrate conditions. The flexible bonding agent should have a minimum tensile strength of 15 MPa (2000 psi) for thermoset elastomer, or a minimum tensile strength of 0.35 MPa (50 psi) for structural spray foam insulation. The flexible bonding agent should have a minimum 300% elongation flexural strength for sprayed elastomer, and 150% for structural closed cell spray foam insulation, and should adhere tenaciously multiple substrates including wood, steel, composites and concrete. It should remain flexible at temperatures as low as −40° C. (−40° F.), and should permit application of multiple coats over one another. According to one embodiment, the sprayed elastomer may have Shore A hardness rating of between 85.2 and 86.2 or a Shore D hardness rating of between 54.5 and 55.5. Other hardness ratings are also possible within the scope of the invention. The spray foam insulation should have a minimum core density of 28 kg/m³ (1.75 pounds per cubic foot).

Existing prior art building restraint systems are designed to lessen the effects of powerful seismic and storm events only to the extent necessary to maintain structural integrity long enough to permit evacuation or rescue to save lives. The structure itself may suffer extensive damage and require extensive repairs to reattach the structural sheathing, or the building may be condemned to demolition. In contrast, the restraint system of the present invention not only maintains structural integrity to the extent necessary for the structure to survive one powerful seismic or storm event, but to survive multiple such events. The restraint system of the present invention achieves this improved outcome by holding the structural fasteners in place during the seismic or storm event so they can effectively perform their function of maintaining the structural integrity of the building.

The restraint system of the present invention is easy to apply to existing or new structures, greatly reduces the costs of seismic upgrades to buildings, does not interfere with construction schedules, and is highly effective in preventing structural fasteners from working their way loose, out or through the structural sheathing, or breaking off entirely.

The system is able to compensate for natural settling and shrinkage of structures, and is applicable to all site and factory assembled, platform or balloon framed, wood or light gauge steel construction for single and multi-family residential, commercial, industrial and institutional structures, whether single or multi story structures.

The restraint system of the present invention is compatible with building codes around the world. The degree of protection may be adjusted to meet the design parameters for a particular structure. Increased protection may be achieved by increasing the width of spray application, or by applying multiple coats to increase the thickness of the bonding agent.

According to the present invention, the sprayed elastomer is applied to the interior as well as the exterior of a building structure. According to another embodiment, the present restraint system allows use of sprayed structural foam insulation for the interior application, along with a sprayed structural flexible bonding agent for the exterior application, to act as one system in providing a dual purpose insulation and restraint system. In this embodiment, a structural closed cell spray foam insulation may be applied to the interior of the structure in lieu of the sprayed elastomer.

In operation, at framing completion or at the completion of a phased portion of the construction, the structural flexible bonding agent is applied in a generally linear spray pattern at the locations specified in the figures. The flexible bonding agent is applied generally in a linear spray pattern approximately 100 mm (4″) to 255 mm (10″) wide and centered over the structural components that are being covered and restrained. The structural flexible bonding agent in elastomer form should be applied approximately 5 mm-7 mm ( 3/16″-¼″) thick. Special care should be taken to ensure the fastener strips are covered. In lieu of applying the structural flexible bonding agent in elastomer form to the interior portions of a structure, a flexible structural foam insulation may be applied to fill a stud or other cavity to provide the required interior portion of the restraint system to the structural components.

Wherever structural fasteners are used to connect together two or more structural components, the flexible bonding agent may be applied over the fasteners to prevent the fasteners from losing their function during a seismic or storm event. The structural flexible bonding agent will ensure the structural fasteners are prevented from working loose, out or through the structural sheathing, or breaking off, thus maintaining the connection of the fastener to the structural framing. The restraint system of the present invention acts to completely integrate the structural components and bind them together as a single unit.

Referring now to FIGS. 2 and 3, these drawings depict a wall stud (1) vertically disposed above a subfloor (3), which is over a floor joist (4). Adjacent the exterior wall surface, a floor rim joist (5) abuts the floor joist. Wall sheathing (6) is applied to the exterior of the wall stud. An anchor bolt assembly (8) passes through a sill plate (9) and sill plate gasket (10) or equivalent into a structural foundation wall (11). In FIG. 2, a top or bottom wall plate (2) is shown below the wall stud.

According to the present invention, a structural flexible bonding agent (7) is sprayed or otherwise applied adjacent selected connection points between structural components. As shown in FIG. 2, the flexible bonding agent is applied at the interior lower end of the wall sheathing along the area at which it is adjacent the wall plate, as well as along the exterior of the area at which the wall sheathing is in proximity to the subfloor and the floor rim joist, and along the area at which the floor rim joist, sill plate, sill plate gasket and structural foundation wall are adjacent. FIG. 3 depicts application of the flexible bonding agent along the exterior of the area at which the wall sheathing is in proximity to the subfloor, and the floor joist, and along the area at which the floor rim joist, sill plate, sill plate gasket and structural foundation wall are adjacent, as well as into the gaps formed at the top, middle, or bottom edges of the structural sheathing.

Referring now to FIG. 4, the flexible bonding agent of the restraint system is depicted applied along the connection area between the wall sheathing and the wall plate; exterior to the wall sheathing, subfloor and floor rim joist; exterior to the floor rim joist, wall plate and wall sheathing, and along the connection between the wall sheathing, a lintel sill opening (14) and a jack stud opening (15). FIG. 4 depicts a lintel opening (12) and a lintel space opening (13) above the lintel sill opening.

Referring now to FIG. 5, the flexible bonding agent of the restraint system is depicted applied along the connection area between the wall sheathing and the wall plate for an upper level; exterior to the wall sheathing, subfloor and floor rim joist; exterior to the floor rim joist, wall plate and wall sheathing, and along the connection between the wall sheathing and a wall plate for a lower level.

Referring now to FIG. 6, a jack stud opening is shown above a sill opening (17) disposed above a trimmer stud opening (18). The flexible bonding agent is applied into the jack stud opening, along the connection area between the wall sheathing and the top of the sill opening, and along the connection area between the interior of the wall sheathing and the bottom of the sill opening.

Referring now to FIG. 7, the top of a wall stud is shown where it is adjacent a roof truss (20). Roof sheathing (21) is disposed above the roof truss. Flexible bonding agent may be applied between the interior of the wall sheathing and bottom of a wall plate, along the exterior of the wall sheathing where it is adjacent the roof truss, and between the roof truss and roof sheathing.

Referring now to FIG. 8, flexible bonding agent may be applied between the roof truss and roof sheathing, along the exterior of the wall sheathing where it meets the roof truss, along the exterior of the wall sheathing where it meets the lintel sill opening, and into a jack stud opening.

Referring now to FIG. 9, an interior view of a framed wall with a window and a door is depicted, showing the interior component of the sprayed elastomer as viewed from the interior. The section marked “A” depicts a portion of wall which contains a framed window opening. The section marked “B” depicts a portion of wall which contains an exterior vertical joint of the structural sheathing, and the section marked “C” depicts a section of wall which contains a framed door opening. FIG. 1 OA, 10B, and 1 OC show top view cross sections, below the top plates of the wall, of section “A”, section “B” and section “C”, respectively, of FIG. 9, including openings for jack studs (15), king studs (16), and trimmer studs (18).

FIGS. 11A, 11B, and 11C show the application of the interior and exterior bonding agent components at typical vertical structural sheathing joints and at a framed exterior corner.

Referring now to FIG. 12, structural flexible spray foam insulation bonding agent (22) may be applied between wall studs (1) and wall sheathing (6), in combination with flexible structural bonding agent applied to the exterior of wall sheathing where it joins other structural components.

It will be appreciated by those skilled in the art that other variations of the preferred embodiment may also be practised without departing from the scope of the invention.

Claims

1. A system for structural restraint of structures against seismic and storm damage, the system comprising:

a plurality of structural framing components;

a plurality of structural sheathing components;

a plurality of structural fasteners;

one or more structural foundations; and

a structural bonding agent.

2. The system of claim 1, wherein the structural bonding agent is a thermoset elastomer having a tensile strength of at least 15 MPa (2000 psi).

3. The system of claim 2 wherein the structural bonding agent has an elastomeric flexural strength of at least 300%.

4. The system of claim 3, wherein the structural bonding agent remains flexible to temperatures as low as −40° C. (−40° F.).

5. The system of claim 1, wherein the structural bonding agent is a spray foam insulation having a tensile strength of at least 0.35 MPa (50 psi).

6. The system of claim 5 wherein the structural bonding agent has an elastomeric flexural strength of at least 150%.

7. The system of claim 6, wherein the structural bonding agent remains flexible to temperatures as low as −40° C. (−40° F.).

8. Use of a structural bonding agent to reinforce building structures against seismic and storm damage by preventing egress of structural fasteners from structural building components.

9. The use of the structural bonding agent as in claim 8, wherein the structural bonding agent is a thermoset elastomer.

10. The use of the structural bonding agent as in claim 8, wherein the structural bonding agent is a spray foam insulation.

11. A method of reinforcing a structure against seismic or storm damage comprising the steps of:

framing a desired structure;

applying a structural flexible bonding agent over structural fasteners at selected locations of the framed structure to achieve a desired thickness.

12. The method of reinforcing a structure of claim 11, further comprising injecting the structural flexible bonding agent into a structural cavity.

13. The method of claim 11, wherein the flexible structural bonding agent is applied by spraying.

14. The method of claim 13, wherein the flexible bonding agent is applied to an area of between 100 mm (4″) and 255 mm (10″) wide centered over the joint between structural components.

15. The method of claim 13, wherein the flexible structural bonding agent is applied to selected locations on the interior of the framed structure, and corresponding selected locations on the exterior of the framed structure.

16. The method of claim 15, wherein the flexible structural bonding agent applied to selected locations on the interior of the framed structure is a thermoset elastomer, and the flexible bonding agent applied to corresponding selected locations on the exterior of the framed structure is a spray foam insulation.