Fire-resistant wooden I-joist

Abstract

This application relates to I-joists which are configured to resist fire damage. Specifically, the present application relates to reinforcing I-joists with reinforcing members configured to provide structural support and/or to provide a physical barrier to fire. This may help the I-joists to maintain structural integrity during a fire and so help improve safety during evacuation of a building and during fire-fighting operations.

Claims

1. A wooden I-joist comprising: a first flange; a second flange positioned opposite to the first flange; a continuous web spanning between the first flange and the second flange, such that each of the first and second flanges protrude laterally away from the web; multiple pairs of spaced-apart reinforcing members positioned along the length of the continuous web, wherein each reinforcing member is a single planar sheet of oriented strand board configured to span between facing surfaces of the first and second flanges, and enclose at least a portion of the outer surface of the web; a height of each reinforcing member being no greater than a distance between the facing surfaces of the first and second flanges; and a combined thickness of each pair of reinforcing members and the web enclosed therebetween being less than a width of the first and second flanges.

2. The wooden I-joist of claim 1, wherein the reinforcing members are coated with an intumescent coating.

3. The wooden I-joist of claim 1, wherein each pair of reinforcing members comprises two reinforcing members located on opposite sides of the web at the same axial position along the I-joist.

4. The wooden I-joist of claim 1, wherein adjacent reinforcing members are positioned to be at most 54 inches (140 cm) apart along the axis of the !-joist.

5. The wooden I-joist of claim 1, wherein the reinforcing members are connected to the facing surfaces of the first and second flanges using nails or screws.

6. The wooden I-joist of claim 1, wherein the reinforcing members are connected to the facing surfaces of the first and second flanges using one or more of: nails; screws; toenails; skewed nails; and skewed screws.

7. The wooden I-joist of claim 1, wherein the reinforcing members are connected to the facing surfaces of the first and second flanges using nails which penetrate through the flange into the reinforcing members through the respective facing surface.

8. The wooden I-joist of claim 3, wherein each pair of reinforcing members are connected to each other using one or more nails or screws which penetrate through the web.

9. The wooden I-joist of claim 1, wherein the sides of the web are at least partially covered with a layer, wherein the layer comprises one or more of: a fire-resistant layer; and a moisture-resistant layer.

10. The wooden I-joist of claim 1, wherein the reinforcing members are at least partially covered with a layer, wherein the layer comprises one or more of: a fire-resistant layer; and a moisture-resistant layer.

11. The wooden I-joist of claim 1, wherein the flanges are at least partially covered with a layer, wherein the layer comprises one or more of: a fire-resistant layer; and a moisture-resistant layer.

12. The wooden I-joist of claim 1, wherein the I-joist is configured to satisfy ICC-ES acceptance Criteria 14 approved in June 2016.

13. The wooden I-joist of claim 1, wherein the reinforcing members are configured not to protrude laterally away from the web farther than the first and second flanges.

14. The wooden I-joist of claim 1, wherein the flanges are formed from 24 lumber.

15. The wooden I-joist of claim 1, wherein at least one reinforcing member is connected directly to the facing surfaces of the first and second flanges.

16. A kit of parts comprising: a first flange; a second flange positionable opposite to the first flange; a continuous web configured to span between the first flange and the second flange such that each of the first and second flanges protrude laterally away from the web; and multiple pairs of spaced-apart reinforcing members positionable along the length of the continuous web, wherein each reinforcing member is a single planar sheet of oriented strand board configured to span between facing surfaces of the first and second flanges, and enclose at least a portion of the outer surface of the web; a height of each reinforcing member being no greater than a distance between the facing surfaces of the first and second flanges; and a combined thickness of each pair of reinforcing members and the web enclosed therebetween being less than a width of the first and second flanges.

17. The kit of parts of claim 16, wherein the kit of parts comprises: an unreinforced I-joist comprising the first and second flanges connected to the web; and multiple reinforcing members configured to span between facing surfaces of the first and second flanges.

18. A method of manufacture comprising: inserting a I-joist into a building under construction, the I-joist comprising: a first flange; a second flange positioned opposite to the first flange; a continuous web configured to span between the first flange and the second flange, such that each of the first and second flanges protrude laterally away from the web; and thereafter connecting multiple pairs of spaced-apart reinforcing members positioned along the length of the continuous web, such that each reinforcing member is a single planar sheet of oriented strand board configured to span between facing surfaces of the first and second flanges, and encloses at least a portion of the outer surface of the continuous web; a height of each reinforcing member being no greater than a distance between the facing surfaces of the first and second flanges; and a combined thickness of each pair of reinforcing members and the web enclosed therebetween being less than a width of the first and second flanges.

19. The wooden I-joist of claim 1, wherein: a length of each reinforcing member is greater than the height thereof.

20. The wooden I-joist of claim 1, wherein: the combined thickness of each pair of reinforcing members and the web enclosed therebetween is less than one-half a width of the first and second flanges.

21. The wooden I-joist of claim 20, wherein the thickness of each reinforcing member is equal to the thickness of the web.

22. The wooden I-joist of claim 21, wherein the flanges are formed from 24 lumber and the thickness of each reinforcing member is less than .

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described with reference to the drawings in which:

(2) FIGS. 1a and 1b is a side view and cross-section of a first embodiment of an I-joist.

(3) FIGS. 2a and 2b is a side view and cross-section of a second embodiment of an I-joist.

(4) FIGS. 2c and 2d is a side view and cross-section of a further embodiment of an I-joist.

(5) FIG. 3 is an overhead plan of a floor construction comprising I-joists.

(6) FIGS. 4 and 5 are cross sections of the floor construction of FIG. 3.

(7) FIG. 6 is an overhead plan of a floor construction comprising I-joists.

(8) FIG. 7 is a cross-section of the floor construction of FIG. 6.

(9) FIGS. 8a and 8b is a side view and a cross-section of a further embodiment of an I-joist.

(10) FIGS. 9a and 9b are perspective views of the embodiment of FIG. 8a incorporated into a floor structure.

DETAILED DESCRIPTION OF THE INVENTION

(11) In accordance with the present disclosure, I-joists are described. The I-joists described herein comprise reinforcing members configured to help improve structural integrity of the I-joists (particularly during a fire).

(12) A standard, unprotected I-Joist may fail during a fire because the web, which connects the top flange to the bottom, burns through quickly (e.g. in approximately 5 minutes). The I-Joist is further degraded as the top and bottom flanges continue to burn after the web has burned through, and are weakened until there is no load carrying capability.

(13) In embodiments of the present disclosure, the top and bottom flanges may have more mass (utilizing 24s instead of 23s). In addition, the top flange is connected to the bottom flange by a specifically designed, proprietary system of reinforcing members (e.g. blocks of wood or OSB), installed at certain intervals along the I-Joists, to bolster the connection of the top flange to the bottom flange and/or to protect and reinforce the web. The reinforcing members may be treated with an intumescent, proprietary, fire resistant paint. For example, intumescent paint is used on OSB panel products to separate buildings where combustible cladding is used (like vinyl siding). The intumescent paint may comprise hydrates, sodium silicates and/or graphite. The intumescent paint on the web may provide 15 minute fire separation as well as reduces the ability of the flame to spread (e.g. ASTM E-84 Class A rating, and in addition to the structural effect of the reinforcing members, they shield the web between the reinforcing members from the fire, maintaining the structural connection of the top flange to the bottom flange provided by the web. The reinforcing members may be specifically cut approximately 1/16 small on each end so they can be easily inserted between the flanges. During a fire the intumescent coating expands to fill this 1/16 gap so to resist heat and flame from degrading the web. In the full scale floor assembly fire test, it is shown that embodiments of the modified I-Joists installed with the reinforcing members, will exceed the equivalency requirements mandated by the 2012 IRC Section R501.3.

(14) In the present disclosure, the specific modifications, method of manufacture, and method of installation describe how to help improve resistance to failure in the event of a fire for an I-joist, and thereby help meet or exceed the requirements of Section R501.3 of the 2012 IRC.

I-Joist Example 1

(15) As shown in FIG. 1a and FIG. 1b, according to a first embodiment of the present disclosure, there is provided a wooden I-joist 100 comprising:

(16) a first flange 101;

(17) a second flange 102 positioned opposite to the first flange 101;

(18) a web 103 spanning between the first flange and the second flange, such that each of the first and second flanges protrude laterally away from the web; and

(19) at least one reinforcing member 114a, 115a, 116a configured to span between, and be connected directly to, facing surfaces 101a, 102a; 101b, 102b of the first and second flanges 101, 102, wherein each reinforcing member encloses at least a portion of the outer surface of the web.

(20) The reinforcing member may enclose at least a portion of the outer surface of the web by being configured such that an inner surface of the reinforcing member abuts an outer surface of the web. It will be appreciated that the area of the outer surface of the web enclosed may span between the first and second flanges 101, 102.

(21) Coordinate System

(22) For the purposes of this disclosure, the axis of along the I-joist 100 is the z-axis. The length of a particular component will correspond to the dimension along this z-axis. The axis perpendicular to the web surface is the x-axis. The width of a particular component will correspond to the dimension along this x-axis. The axis perpendicular to the x-axis and to the z-axis is the y-axis. The height of a particular component will correspond to the dimension along this y-axis. This is shown in FIG. 1a.

(23) Materials

(24) In this embodiment, the first flange 101 and the second flange 102 are made of wood. In particular, the first and second flanges are made of SPF Lumber, which comprises wood from spruce, pines and/or fir trees. In this case, the first and second flanges 101, 102 are wooden boards with a substantially rectangular cross section. In each of the first and second flanges 101, 102, one surface comprises a groove configured to receive the web 103.

(25) In this embodiment, the web 103 is formed from oriented strand board (OSB). It will be appreciated that in other embodiments, the web 103 may be formed from wood or other processed wood fibres (e.g. plywood).

(26) In this case the dimensions of the first and second flanges 101, 102 are the same. It will be appreciated that in some embodiments, the first flange 101 may have different dimensions to the second flange 102. For example, the height and/or width of the first flange 101 may be greater or less than the corresponding dimension of the second flange 102.

(27) In this case, each of the reinforcing members 114a, 115a, 116a comprises wood.

(28) In this case, the reinforcing members are coated with a proprietary fire resistant intumescent paint. The intumescent paint serves two purposes: it helps slow the burning of the reinforcing member itself, and as the intumescent paint is heated, it expands (e.g. as a cellular foam) and seals any crack (or gap) between the reinforcing member and the top and bottom flange. This seals the web from the heat and flames, protecting the integrity of the web situated behind the reinforcing member.

(29) Construction

(30) In this case, the reinforcing members are arranged in spaced-apart pairs 114a, 114b, each pair of reinforcing members comprising two reinforcing members located on opposite sides of the web at the same axial position along the I-joist 100. That is, the reinforcing member pairs 114a, 114b are arranged such that at least a portion of the web 103 is enclosed on opposing sides by the reinforcing members. This may help ensure that this portion of the web 103 is protected on both sides from water and/or fire. Spacing the reinforcing members apart along the axis of the I-joist may allow the overall weight of the I-joist to be reduced.

(31) When the I-joist is being constructed, the web 103 is inserted into the grooves in the first and second flanges 101, 102 and glued. That is, in this case, the web is connected to the flanges with glue. It will be appreciated that the groove may or may not be positioned in the middle of the width of the first and second flanges 101, 102.

(32) Each reinforcing member in this case is connected to the respective facing surfaces 101a, 102a; 101b, 102b of the first and second flanges 101, 102 by one or more fasteners 121a-d. In this case, each reinforcing member is connected directly to the first and second flanges by a toenail 121a-d (or skewed nail) which is driven from an exposed surface of the reinforcing member 114a, 114b, through the reinforcing member at an angle and into the flange 101, 102.

(33) In addition, in this example, the pair of reinforcing members 114a, 114b are connected to each other using one or more fasteners 122 (nails in this case) which penetrate through the web 103.

(34) Dimensions

(35) In this case, the width of the web 103, W.sub.W, is approximately 0.39 inches (1 cm). The height of the web 103, H.sub.W, may be different in different embodiments. In this case, the height of the web is 6.5 inches (16.5 cm). The length of the web is related to the length of the I-joist, L.sub.I, which may be dependent on the application. For example, an I-joist may have a length of more than 14 feet (4.3 m)

(36) In this case, the width of the first and second flanges 101, 102, W.sub.F1, W.sub.F2 is around 3.5 inches (9 cm). The height of the first and second flanges 101, 102, H.sub.F1, H.sub.F2 is around 1.5 inches (4 cm). That is, the first and second flanges 101, 102 are formed from 24 boards. It has been found that using 24 flanges may help satisfy the test described in ASTM E119 section 8.6 (Edition approved May 1, 2011. Published May 2011; DOI: 10.1520/E0119-11). The length of the first and second flanges is related to the length of the I-joist, L.sub.I, which may be dependent on the application.

(37) In this case, each reinforcing member 114a, 114b, 115a, 116a is substantially cuboid-shaped (e.g. block-shaped).

(38) The height of the reinforcing member 114a, 114b, 115a, 116a corresponds to the height of the web 103 between the facing surfaces. That is, when in place, the reinforcing member 114a, 114b, 115a, 116a simultaneously abuts the inner surfaces of both the first and second flanges.

(39) In this case, the length of the reinforcing member 114a, 114b, 115a, 116a is less than the height of the reinforcing member. It will be appreciated that, in other embodiments, the length of the reinforcing member 114a, 114b, 115a, 116a may be greater or equal to the height of the reinforcing member (e.g. the height of web between the facing surfaces).

(40) In this case, the width of the reinforcing members 114a, 114b, 115a, 116a is around 1.5 inches (4 cm). That is, in this case the width of the reinforcing members 114a, 114b, 115a, 116a is less than the width of the facing surfaced on the first and second flanges. This means that, when in place, the reinforcing members 114a, 114b, 115a, 116a are configured not to protrude laterally away from the web farther than the first and second flanges 101, 102.

(41) In this case, adjacent reinforcing members 114a, 115a, 116a (e.g. reinforcing member pairs) are positioned to be 54 inches (140 cm) apart along the axis of the I-joist. It will be appreciated that, in other embodiments, adjacent reinforcing members may be positioned closer together or farther apart. It has been found that positioning the reinforcing members at most 54 inches (140 cm) apart along the axis of the I-joist may help satisfy the test described in ASTM E119 section 8.6.

(42) In some embodiments, a reinforcing member 115a or reinforcing member pair is positioned at the mid-point along the length of the I-joist. The other reinforcing members or member pairs are, in this case, positioned with respect to this central reinforcing member or reinforcing member pair.

(43) Coatings

(44) The wooden I-joist may comprise a fire-resistant layer and/or a moisture-resistant layer (e.g. in the form of a coating).

(45) In this case, the sides of the web and the reinforcing members are at least partially covered with a layer, wherein the layer comprises a fire- and moisture-resistant layer. In this case, the layer is a coating applied at a 3-4 mm wet film thickness.

(46) In this case, the flanges are not covered although it will be appreciated that in other embodiments, the flanges may be covered with a fire-resistant layer and/or a moisture-resistant layer. It will be appreciated that some coating run-off from the application process may be expected on the flanges.

(47) Alternative Fastener Configurations

(48) As shown in FIG. 2a and FIG. 2b, according to a second embodiment of the present disclosure, there is provided a wooden I-joist 200 comprising:

(49) a first flange 201;

(50) a second flange 202 positioned opposite to the first flange 201;

(51) a web 203 spanning between the first flange and the second flange, such that each of the first and second flanges protrude laterally away from the web; and

(52) at least one reinforcing member 214a, 215a, 216a configured to span between, and be connected directly to, facing surfaces 201a, 202a; 201b, 202b of the first and second flanges 201, 202, wherein each reinforcing member encloses at least a portion of the outer surface of the web.

(53) The reinforcing member may enclose at least a portion of the outer surface of the web by being configured such that an inner surface of the reinforcing member abuts an outer surface of the web. It will be appreciated that the area of the outer surface of the web enclosed may be configured to substantially span between the first and second flanges 201, 202 (e.g. before a fire, or after a fire has expanded any intumescent coating).

(54) The second embodiment is similar to the first embodiment in most respects. However, unlike the previous embodiment, in this embodiment, each reinforcing member in this case is connected to the respective facing surfaces 201a, 202a; 201b, 202b of the first and second flanges 201, 202 by one or more fasteners 221a-d in a different way. In this case, each reinforcing member is connected directly to the first and second flanges by nails 221a-d which are driven from an exposed surface of the flange 201, 202 into the reinforcing member 214a, 214b. The exposed surface is on the opposite side of the flange to the facing surfaces.

(55) In this case, reinforcing members (or filler blocks) will be installed at mid-span, every 4 (maximum) from mid-span, and at the joist ends. Mid-span 615 and intermediate 614, 616 reinforcing members (excluding end reinforcing members 613, 616) are secured, in this case, to the upper and lower flanges with two 2 subfloor screws at the top and bottom of each element on each side of the joist. These screws are to be installed through the face of the top and bottom flanges. Reinforcing members at I-joist ends will be secured with one 2 subfloor screw at the top and bottom on each side of the joist. A single 2 subfloor screw to be installed through the face of each reinforcing member will fasten the two opposing 26 reinforcing members to the web.

(56) As in the first embodiment, pairs of reinforcing members 214a, 214b are connected to each other using one or more fasteners 222 (nails in this case) which penetrate through the web 203.

(57) In addition, in this case, there are additional end reinforcing members 213a-b, 217a positioned at each end of the I-joist.

(58) Alternative Block-Type

(59) As shown in FIG. 2c and FIG. 2d, according to a third embodiment of the present disclosure, there is provided a wooden I-joist 400 comprising:

(60) a first flange 401;

(61) a second flange 402 positioned opposite to the first flange 401;

(62) a web 403 spanning between the first flange and the second flange, such that each of the first and second flanges protrude laterally away from the web; and

(63) at least one reinforcing member 414a, 415a, 416a, 417a, 418a configured to span between facing surfaces 401a, 402a; 401b, 402b of the first and second flanges 401, 402, wherein each reinforcing member encloses at least a portion of the outer surface of the web.

(64) The reinforcing member may enclose at least a portion of the outer surface of the web by being configured such that an inner surface of the reinforcing member abuts an outer surface of the web. It will be appreciated that the area of the outer surface of the web enclosed may be configured to substantially span between the first and second flanges 401, 402 (e.g. before a fire, or after a fire has expanded any intumescent coating).

(65) The second embodiment is similar to the first embodiment in most respects. However, unlike the previous embodiment, in this embodiment, each reinforcing member in this case is connected to the respective facing surfaces 401a, 402a; 401b, 402b of the first and second flanges 401, 402 by one or more fasteners 421a-d in a different way. In this case, the reinforcing members are connected directly to the second flange by 3 inch (#10) flat head wood screws 421b, 421d which are driven from an exposed surface of the flange 401, 402 into the reinforcing member 414a, 414b. The exposed surface is on the opposite side of the flange to the facing surfaces. In this case, each reinforcing member is connected directly to the first flange by 3 inch (#10) flat head wood screws 421a, 421c which are driven from an exposed surface of the reinforcing member 414a, 414b, through the reinforcing member at an angle and into the flange 401. It will be appreciated that other fasteners (e.g. nails or other screw types) may be used.

(66) In this case, the block size and configuration is different. In this case, the reinforcing members (or filler blocks) are 28 blocks of wood which are installed at mid-span, every 3 feet from mid-span (e.g. including one at mid-span).

(67) As in the first embodiment, pairs of reinforcing members 414a, 414b may or may not also be connected to each other using one or more fasteners (not shown) which penetrate through the web 403.

(68) A floor based on this embodiment was tested following the test methodology described in ASTM E119, Standard test methods for fire tests of building and construction materials and AC14, Acceptance criteria for prefabricated wood I-joists. It was found that the reinforcing members compensated for the web being burned in order to maintain structural load. Some of the calculations for this test are shown in the Calculations of Parameters for Second Fire Performance Test section below.

Floor Construction: Example 1

(69) FIG. 3 is a plan view of a floor construction comprising the I-joists 300a-g described in relation to the first embodiment. In this case, the floor is rectangular with a two opposing edges and two opposing sides. In this case, the joists 300a-g are configured to span between the opposing edges (and are arranged parallel to two opposing sides). In this case, the edges are longer than the sides. It will be appreciated that in other embodiments, the edges may be the same or smaller than the sides. The side-to-side distance, S.sub.SS, in this case is 18 feet (5.5 m). The edge-to-edge distance, S.sub.EE, in this case is 14 feet 2.5 inches (4.3 m).

(70) In this case, the distance between the centres of adjacent I-joists 300a-g, S.sub.II, is 2 feet (60 cm). The distance between the closest I-joist 300a, 300g to a side wall and the side wall is greater than the inter I-joist distance. In this case, the distance between the closest I-joist and the side wall is 3 feet (90 cm). In this case, seven I-joists 300a-g are used for this subfloor.

(71) Each I-joist 300a-g in this example comprises three pairs of reinforcing members (e.g. 314, 315, 316). One of the reinforcing member pairs (e.g. 315) is located centrally between the two edges (e.g. halfway along the axis of the I-joist).

(72) In this case, the ends of the joists are placed on 24 bearing plates 332. This is more clearly shown in FIG. 4 which is a cross-section view through section A-A in FIG. 3; and in FIG. 5 which is a cross-section view through section B-B in FIG. 3. In this case, the I-joists are fastened to the bearing plates with fasteners 342. In this case, the fasteners 342 comprise two 10d (3 or 7.5 cm) nails, one toe nailed through the face of the flange on each side of the web.

(73) In addition, rim boards 331 are used to close both sides and edges of the assembly around the perimeter. Each end of the I-joists is fastened to the rim board 331 with fasteners 341a-d, which in this case are two 8d (2 or 6.4 cm) nails on both the top and bottom flanges. The bottom of the rim board is fastened to the bearing plate around the perimeter with fasteners, which are in this case with 8d (2 or 6.4 cm) nails at 6 on centre.

(74) The subfloor layer 333 in this case comprises a single layer of 23/32 (nominal or 2 cm) thickness Tongue and Groove (T&G) oriented strand board (OSB) placed over the joists with the 8 (2.4 m) long edges positioned at right angles to the joists. The subfloor is connected to framing members using 8d nails at 6 on centre spacing at joints and 8 on centre for the construction site.

(75) In this case, the subfloor 333 is constructed by first installing unreinforced I-joists in the floor. Once the floor area has been covered such that precipitation cannot reach the I-joists (e.g. by installing a roof on the building), the reinforcing members are installed. This means that if the reinforcing members are covered with a layer (e.g. a coating) which is fire resistant but not moisture resistant, the layer material may be protected from rain or other precipitation. In addition, other fire resistant materials may be applied after the floor area has been covered. For example, any remaining exposed area of the web may be provided with a layer of drywall (e.g. comprising gypsum plaster). For example, a layer of drywall may be attached to each side of the exposed web using fasteners (e.g. nails, screws and/or staples). The drywall may comprise fiberglass or vermiculite which may improve fire-resistant properties.

Floor Construction: Example 2

(76) As shown in FIG. 6, in a second embodiment, the subfloor may be constructed using I-joists of the second embodiment (FIGS. 2a and 2b). In this case, the arrangement of the I-joists in the floor may be similar to that described in relation to FIG. 3.

(77) The side-to-side distance, S.sub.SS, in this case is 18 feet (5.5 m). The edge-to-edge distance, S.sub.EE, in this case is 14 feet 2.5 inches (4.3 m).

(78) In this case, the distance between the centres of adjacent I-joists 600a-i, S.sub.II, is 2 feet (60 cm). The distance between the closest I-joist 600a, 600i to a side wall and the side wall is less than the inter I-joist distance. In this case, the distance between the closest I-joist and the side wall is 1 foot (30 cm). In this case, nine I-joists 600a-i are used for this subfloor.

(79) Each I-joist 600a-i in this example comprises four pairs of reinforcing members (e.g. 613-617). One of the reinforcing member pairs (e.g. 315) is located centrally between the two edges (e.g. halfway along the axis of the I-joist).

(80) In this case, the end reinforcing members allow the rim board 631 in a different way as shown in FIG. 7.

(81) In this case, the ends of the joists are placed on 24 bearing plates 632. In addition, rim boards 631 are used to close both sides and edges of the assembly around the perimeter. Each end of the I-joists is fastened to the rim board 631 with fasteners 641a,d, which in this case are two 8d (2 or 6.4 cm) nails nailed to the end reinforcing members 613a,b. As described above, the end reinforcing members are connected in this case to the flanges by fasteners 223a,c which are nailed through the flange 601 and into the reinforcing members 213a,b.

(82) Although the present invention has been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention as understood by those skilled in the art.

(83) Alternative Reinforcing Member

(84) As shown in FIG. 8a and FIG. 8b, according to a further embodiment of the present disclosure, there is provided a wooden I-joist 800 comprising:

(85) a first flange 801;

(86) a second flange 802 positioned opposite to the first flange 801;

(87) a web 803 spanning between the first flange and the second flange, such that each of the first and second flanges protrude laterally away from the web; and

(88) at least one reinforcing member 814a, 815a, 816a configured to span between facing surfaces 801a, 802a; 801b, 802b of the first and second flanges 801, 802, wherein each reinforcing member encloses at least a portion of the outer surface of the web.

(89) The reinforcing member may enclose at least a portion of the outer surface of the web by being configured such that an inner surface of the reinforcing member abuts an outer surface of the web. It will be appreciated that the area of the outer surface of the web enclosed may be configured to substantially span between the first and second flanges 801, 802 (e.g. before a fire, or after a fire has expanded any intumescent coating).

(90) As in previous embodiments, the reinforcing members in this case are arranged in pairs wherein a particular portion of the web 801 is enclosed on both sides by members of a pair (e.g. reinforcing members 814a, 814b)

(91) The second embodiment is similar to the first embodiment in most respects. However, in this case, the reinforcing members are not blocks of wood but rectangular layer portions of OSB (which is the same material as the web in this case). In this case, the length of each reinforcing members is 2 feet and the distance between adjacent reinforcing members is also 2 feet. The thickness of the reinforcing members, W.sub.R1, W.sub.R2, is inches, which in this case, is the same thickness as that of the web, W.sub.W. In this case, the web is painted (e.g. with proprietary and/or intumescent paint). The reinforcing members are painted in this case with intumescent paint (e.g. around 14 mil or 0.4 mm wet). The thickness of the layer portions (e.g. W.sub.R1, W.sub.R2) may be less than inch.

(92) In addition, the flanges in this embodiment are 23 boards (other embodiments may have 24 boards).

(93) In addition, in this embodiment, each reinforcing member in this case is connected directly to the web by inch staples 822a-d which are driven from an exposed surface of the reinforcing members 814a, 815a, 816a and into the web 803. The exposed surface is on the opposite side of the flange to the facing surfaces.

(94) In this case, reinforcing members (or filler blocks) will be installed at mid-span, every 4 foot (maximum) from mid-span.

(95) As in the first embodiment, pairs of reinforcing members 814a, 814b are connected to the web using one or more fasteners 822a-d (nails in this case) which penetrate into the web 203.

(96) It will be appreciated that the width of the OSB reinforcing members may be different in some embodiments (e.g. the reinforcing members may have a width greater than such as 7/16).

(97) I-joists as described above may form part of a floor/ceiling assembly. In multi-family construction building codes may require a minimum of 60 minute fire separation between units (or apartments). A floor/ceiling assembly forms the ceiling of one apartment and the floor of the apartment above. A conventional floor/ceiling assembly is typically made up of the following: I-joistsstandard with no reinforcing members; A subfloor covering and spanning between the I-joists; Light weight concrete poured on top of the subfloor; Insulation (3) (this component is optional)the insulation provides sound reduction performance and thermal insulation; Resilient channelsthese are metal channels that run perpendicular to the joist at typically 16 o/c. The channels again isolate the joist from the gypsum board to provide small pathway for sound to travel. Gypsum (e.g. in the form of drywall)two layers of

(98) FIGS. 9a and 9b show a floor comprising I-joists according to the present disclosure. As shown in FIG. 9a, the floor assembly in this case comprises: I-joists 901each including reinforcing members 915a, a first flange 901; a second flange 902; and a web 903. A subfloor 951 (e.g. formed form wood) covering and spanning between the I-joists; Light weight concrete 955 poured on top of the subfloor. Optional insulation 954 (3)the insulation may help provide sound reduction performance and thermal insulation. Resilient channels 952these are metal channels that run perpendicular to the joist at typically 16 o/c. The channels again isolate the joist from the gypsum board to provide small pathway for sound to travel. Gypsumone layer 953 of fire rated gypsum Optional additional layers 955 (e.g. carpet or wood) overlaid on the concrete layer.

(99) That is, by improving the fire-resistance of the I-joist itself using reinforcing members as described above, the I-joist may require less fire protection from the gypsum (or drywall) layer or layers mounted on the bottom of the floor assembly. That is, the present I-joist may save one layer of drywall (or gypsum) and the labour of installing this additional drywall layer compared with a conventional ceiling/floor assembly.

(100) It will be appreciated that the structure shown in FIGS. 9a and 9b represents one embodiment of the present disclosure. Other embodiment with variations on this structure may also be used. For example, another embodiment may use multiple gypsum layers in conjunction with reinforced I-joists to further increase the fire-resistant properties of the assembly.

(101) Calculations of Parameters for First Fire Performance Test

Appendix 1 Calculation of Load for Equivalent Fire Performance Test

(102) (in accordance with A4.4.1.2 of AC14)
1 Construction Details

(103) TABLE-US-00001 Physical Properties b (flange d (flange h (joist width) depth) height) 1) Joist Type (in) (in) (in) 9 PK35Plus FRI 3.5 1.5 9.5 2) Clear Span 13 ft + 7.5 in = 13.63 ft = 163.5 3) o/c spacing (in): 24 in 4) Sub-floor: 23/32 (nominal ) OSB
2 Calculation of Full ASD Bending Design Load

(104) TABLE-US-00002 End Bearing Length: 2.25 in Design Span: 13.81 ft = 165.75 in 1) Adjusted design moment Mr Reference Design Load Duration Temperature Beam Stability Repetitive Adjusted Design Value Factor Wet Service Factor Factor Member Factor Value Mr C.sub.D C.sub.M C.sub.t C.sub.L C.sub.r Mr lbs-ft lbs-ft 2365 1.0 1.0 1.0 1.0 1.0 2365 Note: Mr = MrC.sub.DC.sub.MC.sub.tC.sub.LC.sub.r 3) Allowable linear joist loading, W.sub.Mr $\begin{matrix} W_{{Mr}^{}} = 8 {Mr}^{} / L^2 \\ = 99 plf \end{matrix}$ 4) Allowable uniform area loading, .sub.Mr $\begin{matrix} _{{Mr}^{}} = W_{{Mr}^{}} / s \\ = 49.6 psf \end{matrix}$
3 50% of full ASD bending design load In fire test, each framing member (I-joist) shall support a load corresponding to 50% of its full ASD bending design lead as following: In full uniform linear load:

(105) $\begin{matrix} W = 50 % W_{{Mr}^{}} \\ = 49.6 plf \end{matrix}$

(106) Calculations of Parameters for Second Fire Performance Test

(107) Determination of Minimum Fire Test Duration of Solid Sawn 210 Floor Joist (in accordance with A4.4.1.5 of AC14)
1 Physical Properties of 210 Before Fire Exposure

(108) TABLE-US-00003 Physical Properties b h A S (Section I (Moment (width) (height) (Area) Modulus) of Inertia) 1) Joist Type (in) (in) (in{circumflex over ()}2) (in{circumflex over ()}3) (in{circumflex over ()}4) 2 10 1.5 9.25 13.88 21.39 98.93 2) Design Span 13.81 ft = 166 in (same as the I-joist design span) (L) 3) o/c spacing 24 in (in): 4) Species and S-P-F No2 & better Grade:
2 Calculation of Full ASD Bending Design Load

(109) TABLE-US-00004 1) Adjusted bending design value Fb Repetitive Adjusted Reference Wet Service Temperature Beam Stability Member Design Design Load Duration Factor Factor Factor Sizer Factor Flat Use Factor Incising Factor Factor Value Fb C.sub.D C.sub.M C.sub.t C.sub.L C.sub.F C.sub.fu C.sub.i C.sub.r Fb psi psi 875 1.0 1.0 1.0 1.0 1.1 1.0 1.0 1.15 1107 2) Allowable bending moment, Ma $\begin{matrix} Ma = F_{b}^{} S \\ = 23677 lbs - in \\ = 1973 lbs - ft \end{matrix}$ 3) Allowable linear joist loading, W.sub.Ma $\begin{matrix} W_{Ma} = 8 Ma / L^2 \\ = 83 plf \end{matrix}$ 4) Allowable uniform area loading, .sub.Ma $\begin{matrix} _{Ma} =_{Ma} / s \\ = 41.4 psf \end{matrix}$
3 50% of the Full ASD Bending Design Load,

(110) $\begin{matrix} = 50 %_{Ma} \\ = 20.7 psf \end{matrix}$
4 Determination of exposure time, t (min)

(111) $\begin{matrix} t = 14.8315 minutes \\ = 0.247 hrs \end{matrix}$

(112) 4.1 Calculation of Effective Char Layer Thickness, a.sub.Char

(113) Effective Char Rate:

(114) $\begin{matrix} _{eff} = 1.2_{r} / t .Math. 0.187 \\ = 1.2 1.5 / t .Math. 0.187 \\ = 2.34 in . / hr \end{matrix}$

(115) Effective Char Layer Thickness:

(116) 0 $\begin{matrix} a_{char} =_{eff} t \\ = 0.58 in \end{matrix}$

(117) 4.2

(118) Physical Properties of 2/10 after Fire Exposure (Dimension Reduced)Fire Exposure on Three Sides

(119) TABLE-US-00005 b h I (width = (height) = S (Section (Moment b 2a.sub.char h a.sub.char A (Area) Modulus) of Inertia) (in) (in) (in{circumflex over ()}2) (in{circumflex over ()}3) (in{circumflex over ()}4) 0.34 8.67 2.99 4.32 18.71

(120) 4.3

(121) Induced Stress Calculated Using Reduced Section Property and 50% of Full Bending Design Load,

(122) F.sub.b-induced

(123) 1) Linear Load w

(124) $\begin{matrix} w^{} = (s / 12) \\ = 41.38 plf \end{matrix}$

(125) 2) Induced Moment Under 50% of Full Bending Design Load

(126) $\begin{matrix} M = w^{} L .Math. 2 / 8 \\ = 986.53 lbs - ft \end{matrix}$

(127) 3) Induced Stress Calculated Using Reduced Section Property and 50% of Full Bending Design Load

(128) $\begin{matrix} F_{b - induced} = M / S^{} \\ = 2743.04 psi \end{matrix}$

(129) 4.4 Calculation of Member Strength for Fire Design, F.sub.b-fire

(130) TABLE-US-00006 Design Strength to Reference Member Flat Beam Design Strength Sizer Volume use Stability Member Value Factor Factor Factor Factor Factor Strength F.sub.b 2.85 C.sub.F C.sub.V C.sub.fu C.sub.L F.sub.b-fire psi psi 875 2.85 1.1 N/A 1.0 1.0 2743.13

(131) 4.5 the Following Condition Must be Met: F.sub.b-inducedF.sub.b-fire i.e. F.sub.b-fireF.sub.b-induced0

(132) 4.6 the Maximum Value of t which Meets the Above Condition could be Found Through an Iterative Procedure (Assume the Result is Acceptable when the Difference is within 0.5 Psi)

(133) $When t = 14.8315 minutes$ $\begin{matrix} F_{b - fire} - F_{b - induced} = 2743.13 - 2743.04 \\ = 0.09 psi \end{matrix}$ So, Minimum fire test duration of equivalent fire test is: T=14.8 minutes

(134) Calculations of Load for One Hour Layer Fire Test (Based on Assembly of FIGS. 9a and 9b)

(135) 1 Construction Details

(136) TABLE-US-00007 Physical Properties b (flange d (flange h (joist width) depth) height) 1) Joist Type (in) (in) (in) 11 PKI20 FRI 2.5 1.5 11 2) Clear Span 13 ft + 7.5 in = 13.63 ft = 163.5 3) o/c spacing (in): 24 in 4) Sub-floor: 23/32 OSB Sheathing 5) Insulation: 3 fiberglass batt 6) Resilient channel @ 16 o/c 7) Ceiling: Pabco Type C gypsum board 8) Rim board: 1 LVL
2 Calculation of Full ASD Bending Design Load End Bearing Length: 2.25 in Design Span: 13.81 ft=165.75 in

(137) TABLE-US-00008 1) Adjusted design moment, Mr Reference Beam Repetitive Adjusted Design Wet Service Temperature Stability Member Design Value Load Duration Factor Factor Factor Factor Factor Value Mr C.sub.D C.sub.M C.sub.t C.sub.L C.sub.r Mr lbs-ft lbs-ft 3079 1.0 1.0 1.0 1.0 1.0 3079 Note: Mr = MrC.sub.DC.sub.MC.sub.tC.sub.LC.sub.r 2) Allowable linear joist loading, W.sub.Mr $\begin{matrix} W_{{Mr}^{}} = 8 {Mr}^{} / L^2 \\ = 129 plf \end{matrix}$ 3) Allowable uniform area loading, .sub.Mr $\begin{matrix} _{{Mr}^{}} = W_{{Mr}^{}} / s \\ = 64.6 psf \end{matrix}$ Note: It is also confirmed that moment is the governing factor for this design.
3 Dead Load of test floor assembly, .sub.Dead

(138) TABLE-US-00009 Area Calculation Average Average Width Length Area Mass Length Weight- Items Description Mass (ft) (ft) (ft{circumflex over ()}2) (lbs/ft) (ft) W.sub.total (lbs) 1) 23/32 OSB Sheathing 2.07 8 14.21 113.67 235.29 2) 3.5 Fiber glass batt 0.37 8 14 112 41.59 3) Resilient channel @ 0.22 84 18.48 16 o/c 4) 5/8 Pabco Type C 2.35 8 13.63 109 256.15 gypsum board 5) 1 1/4 Rim board 4.7 28 131.60 6) I-joists 3.52 56 197.12 7) Nails 10.00 Total 890.23 So, Dead Load of test floor assembly in pst: $\begin{matrix} _{Dead} = W_{total} + Area \\ = 890.23 + 112 \\ = 7.95 psf \end{matrix}$
4 Required Superimposed Load for Test Assembly

(139) The required uniform superimposed load applied on test fire assembly for 24 o/c I-joist spacing (in psf of lbs/ft.sup.2)

(140) $\begin{matrix} _{actual} =_{{Mr}^{}} -_{Dead} \\ = 64.55 - 7.95 \\ = 56.6 psf (lb / {ft}^{2}) \end{matrix}$

Fire-resistant wooden I-joist

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Abstract

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