Wood steel joint
The wood-steel joint design with cement-based heat absorption sections and fixing mechanisms addresses poor fire resistance by absorbing heat, enhancing joint integrity in wood-steel structures.
Patent Information
- Application Number
- JP2025200739
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-11-20
- Publication Date
- 2026-01-29
AI Technical Summary
Hybrid structures combining wood and steel materials face poor fire resistance at their joints.
A wood-steel joint design incorporating steel connecting members, cement-based fillers as heat absorption sections, and fixing sections to prevent direct heat transfer from steel to wood, using structural screws for installation and stabilization.
Enhances fire resistance by absorbing heat with moisture in cementitious fillers, preventing temperature rise from being directly transmitted to wooden components, thus improving joint integrity during fires.
Smart Images
Figure 2026015566000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to wood-steel joints. [Background technology]
[0002] Conventionally, beam string structures have been known that include an upper chord (beam) that is a bending compression member, a lower chord that is a tension member, and a strut that is a compression member that connects the upper chord and the lower chord. Patent Document 1 listed below proposes a configuration in which the upper end of the strut and the wooden upper chord are connected by a diagonal member made of tensioned reinforcing steel. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-37382 Summary of the Invention [Problem to be solved by the invention]
[0004] However, a hybrid structure combining wood and steel materials, as in Patent Document 1, has the problem of poor fire resistance at the joints between the wood and steel materials.
[0005] Therefore, the present invention has been made in consideration of the above circumstances, and provides a wood-steel joint that can improve the fire resistance performance of the joint between wood and steel material. [Means for solving the problem]
[0006] In order to achieve the above object, the present invention employs the following means. In other words, the wood-steel joint of the present invention comprises a wooden upper chord supported by steel connecting members provided on a support member, a steel lower chord, a plurality of steel struts arranged at intervals along the length of the upper chord and the lower chord and connecting the upper chord and the lower chord, and a wood-steel joint that joins the upper chord to at least one of the struts, the lower chord, and the connecting members, and the wood-steel joint is provided with a heat absorbing member that inhibits heat transfer from the steel member to the upper chord.
[0007] In a beam string structure configured in this way, the temperature of the steel members rises in the event of a fire. The heat absorption section inhibits heat transfer from at least one of the steel struts, lower chord members, and joint members to the upper chord member, thereby improving fire resistance.
[0008] Furthermore, in the beam string structure of the present invention, the wood-steel joint has a first joint that joins the upper chord member and the strut, and the first joint has a first heat absorption section in which a cement-based filler is filled in a recess formed from the bottom of the upper chord member upward, the upper end of the strut member embedded in the first heat absorption section, and a first fixing section that fixes the first heat absorption section to the upper chord member.
[0009] In a beam string structure configured in this way, the temperature of the steel struts rises in the event of a fire. At the first joint, the moisture contained in the cementitious filler absorbs the heat of the struts at the first heat absorption section, where the upper ends of the struts are embedded, preventing the temperature rise of the struts from being directly transmitted to the wooden upper chord. At this time, because the first heat absorption section is fixed to the upper chord by the first fixing section, the first heat absorption section does not fall and can continue to absorb the heat of the struts. This improves the fire resistance of the first joint, which is the joint between the wooden upper chord and the steel struts.
[0010] In the beam string structure according to the present invention, the first fixing portion may be a structural screw.
[0011] In a beam string structure configured in this way, the first heat absorption section can be mounted with a structural screw toward the upper chord, improving the ease of installation of the first fixing section.
[0012] Furthermore, in the beam string structure of the present invention, the wood-steel joint may have a second joint that joins the upper chord and the lower chord, and the second joint may have a second heat absorption portion in which a cement-based filler is filled in a recess formed from the lower part of the upper chord upward, an intermediate portion of the lower chord that penetrates the second heat absorption portion, and a second fixing portion that fixes the second heat absorption portion to the upper chord.
[0013] In a beam string structure configured in this way, the temperature of the steel lower chord rises in the event of a fire. At the second joint, the moisture contained in the cement-based filler absorbs the heat of the lower chord at the second heat absorption section, where the middle part of the lower chord is buried, preventing the temperature rise of the lower chord from being directly transmitted to the wooden upper chord. At this time, because the second heat absorption section is fixed to the upper chord by the second fixing section, the second heat absorption section does not fall and can continue to absorb the heat of the lower chord. Therefore, the fire resistance performance of the second joint, which is the joint between the wooden upper chord and the steel lower chord, can be improved.
[0014] Furthermore, in the beam string structure of the present invention, the wood-steel joint may have a third joint that joins the upper end of the support member that supports the upper chord to the upper chord, and the third joint may have a third heat absorption section in which a recess formed from the lower part of the upper chord upward is filled with a cement-based filler, a steel joint material connected to the upper end of the support member and embedded in the third heat absorption section, and a third fixing section that fixes the third heat absorption section to the upper chord.
[0015] In a beam string structure configured in this way, the temperature of the steel joint material rises in the event of a fire. At the third joint, the moisture contained in the cementitious filler absorbs the heat of the joint material in the third heat absorption section where the joint material is embedded, preventing the temperature rise of the joint material from being directly transmitted to the wooden upper chord. At this time, because the third heat absorption section is fixed to the upper chord by the third fixing section, the third heat absorption section does not fall and can continue to absorb the heat of the joint material. Therefore, the fire resistance performance of the third joint, which is the joint between the wooden upper chord and the steel joint material, can be improved. [Effects of the Invention]
[0016] The wood-steel joint assembly according to the present invention can improve the fire resistance of the joint between wood and steel material. [Brief explanation of the drawings]
[0017] [Figure 1] FIG. 1 is a schematic perspective view showing a beam string structure according to an embodiment of the present invention. [Figure 2] FIG. 1 is a schematic front view showing a beam string structure according to an embodiment of the present invention. [Figure 3] FIG. 3 is an enlarged view of part III in FIG. 2. [Figure 4] FIG. 3 is an enlarged view of part IV in FIG. 2. [Figure 5] FIG. 3 is an enlarged view of part V in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION
[0018] A beam string structure according to one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing a beam string structure according to one embodiment of the present invention. A beam string structure 100 according to this embodiment, shown in Figure 1, is applied to the roof frame or floor frame of a building. The beam string structure 100 extends in a first direction (the direction of arrow X shown in Figure 1, etc.) along the horizontal direction. On the roof frame or floor frame, multiple beam string structures 100 are installed at intervals in a second direction (the direction of arrow Y shown in Figure 1, etc.) that is perpendicular to the first direction along the horizontal direction. Both ends of the beam string structure 100 in the longitudinal direction (first direction) are supported by supporting members such as columns 91 (see Figure 2) or walls that extend in the vertical direction (the direction of arrow Z shown in Figure 1, etc.). In each component, the side away from the center in the first and second directions may be referred to as the outside, and the side toward the center may be referred to as the inside.
[0019] FIG. 2 is a schematic front view showing the beam string structure 100. As shown in Figure 2, the beam string structure 100 comprises an upper chord 1, a lower chord 2, beams 3, and a wood-steel joint 10. The wood-steel joint 10 comprises a first joint 4, a second joint 5, and a third joint 6.
[0020] The upper chord member 1 extends in a first direction. In this embodiment, the upper chord member 1 is formed by joining a pair of upper chord components 11, 11 with an upper chord connector 11a. The upper chord components 11 are inclined relative to the horizontal plane so as to gradually rise upward as they approach the center in the first direction.
[0021] FIG. 3 is an enlarged view of part III in FIG. As shown in Figure 3, the upper chord constituent member 11 has a core material 12, a fire-resistant covering portion 13, and decorative wood 14. The core material 12, which is the main part of the upper chord constituent member 11, is made of wood and has a rectangular pillar shape. The fire-resistant covering portion 13 covers the outer surface of the core material 12. The fire-resistant covering portion 13 has a reinforced gypsum board 13a that fits along the outer surface of the core material 12, and a fire-resistant sheet 13b that covers the outer surface of the reinforced gypsum board 13a. The decorative wood 14 covers the outer surface of the fire-resistant covering portion 13.
[0022] As shown in Figure 2, the lower chord member 2 is a steel member. The lower chord member 2 has a first lower chord component 21 and a pair of second lower chord components 22, 22. The first lower chord component 21 and the second lower chord component 22 can be made of steel rods, for example.
[0023] The first lower chord component 21 extends in a first direction. The second lower chord component 22 is inclined so as to gradually rise upward from the end of the first lower chord component 21 toward the outside in the first direction.
[0024] The beam members 3 are installed at two locations spaced apart in the first direction. The beam members 3 are steel members. The beam members 3 extend in the vertical direction. The beam members 3 connect the upper chord member 1 and the lower chord member 2. The lower end of the beam member 3, the end of the first lower chord component 21, and the end of the second lower chord component 22 are joined by joints 21a.
[0025] The first joint 4 joins the upper chord 1 and the strut 3. As shown in FIG. 3, the first joint 4 has a first heat absorption part (heat absorption part) 41, a joining strut 32, and a first fixing part 42. By rotating a nut (not shown) on the strut 3, the strut 3 can be stretched and tension can be introduced into the lower chord 2. By introducing tension, the stress in the upper chord 1 can be controlled.
[0026] An upwardly recessed recess 12a is formed on the lower surface of the core material 12. The first heat absorbing portion 41 is made of mortar (cement-based filler) filled in the recess 12a.
[0027] The beam 3 has a beam body 31 formed in a cylindrical shape. A connecting beam 32 having a male screw is screwed onto the upper end of the beam body 31. The connecting beam 32 penetrates the decorative wood 14 and fire-resistant coating 13 of the upper chord component 11, and the upper end 32u is embedded in the first heat absorption part 41. The first heat absorption part 41 inhibits heat transfer from the steel beam 3 to the upper chord 1.
[0028] The first fixing portion 42 is a screw for wooden construction (for example, Panelead (registered trademark) or the like) that fixes the first heat absorbing portion 41 to the core material 12. By screwing the first fixing portion 42 into the core material 12, the first heat absorbing portion 41 is fixed to the core material 12, and the upper end of the bundle 3 is fixed to the core material 12 via the first heat absorbing portion 41.
[0029] FIG. 4 is an enlarged view of part IV in FIG. As shown in Figure 2, the second joint 5 joins the upper chord member 1 and the lower chord member 2. As shown in Figure 4, the second joint 5 has a second heat absorption portion (heat absorption part) 51, an intermediate portion 22a of the second lower chord component 22, and a second fixing portion 52.
[0030] An upwardly recessed recess 12b is formed on the lower surface of the core material 12. The second heat absorbing portion 51 is made of mortar (cement-based filler) filled in the recess 12b.
[0031] The upper part of the second lower chord component 22 penetrates the upper chord component 11. The upper end 22u of the second lower chord component 22 protrudes from the upper surface of the upper chord component 11. A fire-resistant coating 15 is provided at the upper end 22u of the second lower chord component 22 and at the point on the upper surface of the upper chord component 11 where the second lower chord component 22 penetrates. The middle part 22a of the second lower chord component 22 is embedded in a second heat absorption part 51. The second heat absorption part 51 inhibits heat transfer from the steel second lower chord component 22 to the upper chord member 1.
[0032] The second lower chord component 22 is configured such that the ends of multiple rod members 22b are connected via connecting members 22c. Male threads are formed on the outer peripheral surface of the ends of the rod members 22b, and are threaded into female threads formed on the inner peripheral surface of the connecting member 22c. Furthermore, by rotating the connecting member 22c, tension can be introduced into the lower chord member 2. By introducing tension, the stress in the upper chord member 1 can be controlled.
[0033] The second fixing portion 52 is a screw for wooden construction that fixes the second heat absorbing portion 51 to the core material 12. By screwing the second fixing portion 52 into the core material 12, the second heat absorbing portion 51 is fixed to the core material 12, and the middle portion 22a of the second lower chord constituent member 22 is fixed to the core material 12 via the second heat absorbing portion 51.
[0034] FIG. 5 is an enlarged view of a portion V in FIG. 2, the third joint 6 joins the upper end 91u of the column 91 and the upper chord 1. As shown in FIG. 5, the third joint 6 has a third heat absorption portion (heat absorption portion) 61, a second joint member (joining material) 94, and a third fixing portion 62.
[0035] An upwardly recessed recess 12c is formed on the lower surface of the core material 12. The third heat absorbing portion 61 is made of mortar (cement-based filler) filled in the recess 12c.
[0036] A first joint member 92 is joined to an upper end portion 91u of the column 91 by a joint such as a bolt (not shown). The first joint member 92 is joined to a second joint member 94 by a joint pin 93.
[0037] The second joint member 94 has a plate portion 94a that fits along the underside of the core member 12. The plate portion 94a has a protrusion 94b, such as a bolt, that protrudes upward. The second joint member 94 is a steel member. The plate portion 94a and protrusion 94b of the second joint member 94 are embedded in the third heat absorption portion 61. The third heat absorption portion 61 inhibits heat transfer from the steel second joint member 94 to the upper chord member 1.
[0038] The third fixing portion 62 is a screw for wooden construction that fixes the third heat absorbing portion 61 to the core material 12. By screwing the third fixing portion 62 into the core material 12, the third heat absorbing portion 61 is fixed to the core material 12, and the second joint member 94 of the pillar 91 is fixed to the core material 12 via the third heat absorbing portion 61.
[0039] In the beam string structure 100 configured in this manner, the temperature of the steel struts 3 rises in the event of a fire. At the first joint 4, the moisture contained in the cementitious filler absorbs the heat of the struts 3 at the first heat absorption section 41, where the upper ends 32u of the struts 3 are embedded, and the temperature rise of the struts 3 is not directly transmitted to the wooden upper chord 1. At this time, because the first heat absorption section 41 is fixed to the upper chord 1 by the first fixing section 42, the first heat absorption section 41 does not fall and can continue to absorb the heat of the struts 3. Therefore, the fire resistance of the first joint 4, which is the joint between the wooden upper chord 1 and the steel struts 3, can be improved.
[0040] Furthermore, since the first heat absorption portion 41 can be mounted by simply driving a structural screw toward the upper chord 1, the workability of the first fixing portion 42 can be improved.
[0041] Furthermore, in the event of a fire, the temperature of the steel lower chord 2 rises. At the second joint 5, the moisture contained in the cement-based filler absorbs the heat of the lower chord 2 at the second heat absorption section 51, where the middle section 22a of the lower chord 2 is buried, and the temperature rise of the lower chord 2 is not directly transmitted to the wooden upper chord 1. At this time, because the second heat absorption section 51 is fixed to the upper chord 1 by the second fixing section 52, the second heat absorption section 51 does not fall and can continue to absorb the heat of the lower chord 2. Therefore, the fire resistance performance of the second joint 5, which is the joint between the wooden upper chord 1 and the steel lower chord 2, can be improved.
[0042] Furthermore, during a fire, the temperature of the steel second joint member 94 rises. In the third joint 6, the moisture contained in the cementitious filler absorbs the heat of the plate portion 94a and the protruding portion 94b in the third heat absorption section 61, where the plate portion 94a and the protruding portion 94b of the second joint member 94 are embedded. This prevents the temperature rise of the plate portion 94a and the protruding portion 94b from being directly transmitted to the wooden upper chord 1. Because the third heat absorption section 61 is fixed to the upper chord 1 by the third fixing portion 62, the third heat absorption section 61 does not fall and can continue to absorb the heat of the plate portion 94a and the protruding portion 94b of the second joint member 94. This improves the fire resistance of the third joint 6, which is the joint between the wooden upper chord 1 and the steel second joint member 94.
[0043] The assembly procedures, shapes and combinations of the components, etc. shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., within the scope of the present invention.
[0044] For example, in the embodiment shown above, the beam string structure 100 is provided with the second joint 5 and the third joint 6, but the present invention is not limited to this. The beam string structure 100 only needs to be provided with at least the first joint 4 that joins the upper chord 1 and the beam 3.
[0045] Furthermore, in the above embodiment, a wooden structural screw is used as an example of the first fixing portion 42, but the present invention is not limited to this. For example, the recess 12a may be shaped to widen from the lower end of the core member 12 upward, making it difficult for the first heat absorbing portion 41 to fall out of the recess 12a, thereby fixing the first heat absorbing portion 41 to the upper chord member 1. The second heat absorbing portion 51 and the third heat absorbing portion 61 are similar to the first heat absorbing portion 41.
[0046] The Sustainable Development Goals (SDGs) are 17 international goals that were adopted at the United Nations Summit in September 2015. The beam string structure 100 according to this embodiment can contribute to achieving one of the 17 SDGs, for example, goal 15, "Protect and sustainably sustain the life on land." [Explanation of symbols]
[0047] 1 Top chord 2 Lower chord 3 Bundle material 4 1st joint (wood-steel joint) 5 Second joint (wood-steel joint) 6 Third joint (wood-steel joint) 10 Wood-steel joints 32u Upper end of beam 41 First heat absorption part (heat absorption part) 42 1st fixed part 51 Second heat absorption part (heat absorption part) 52 Second fixed part 61 Third heat absorption section (heat absorption section) 94 Second joining member (joining material) 100 String beam structure
Claims
1. A wood-steel joint that joins a wooden member and a steel member, A wood-steel joint having a heat sink that inhibits heat transfer from the steel member to the wooden member.
2. 2. The wood-to-steel joint according to claim 1, wherein the heat absorbing portion is a recess formed in the wooden member and filled with a cement-based filler.
3. the steel member includes a first steel member disposed below the wooden member and extending in a vertical direction; The wood-steel joint has a first joint that joins the wooden member and the first steel member, The first joint portion is a first heat absorption portion formed by filling a cement-based filler in a recess formed from the bottom to the top of the wooden member; an upper end portion of the first steel member embedded in the first heat absorption portion; The wood-to-steel joint according to claim 1 , further comprising: a first fixing portion that fixes the first heat absorbing portion to the wooden member.
4. The wood-to-steel joint according to claim 3 , wherein the first fixing portion is a structural screw.
5. the steel member includes a second steel member; The wood-steel joint has a second joint that joins the wooden member and the second steel member, The second joint portion is a second heat absorption portion formed by filling a cement-based filler in a recess formed from the bottom to the top of the wooden member; an intermediate portion of the second steel member that passes through the second heat absorption portion; The wood-to-steel joint according to claim 1 , further comprising: a second fixing portion that fixes the second heat absorbing portion to the wooden member.
Citation Information
Patent Citations
Wooden truss beam using steel product for lower chord member
JP1998037382A