NZ264341A

NZ264341A - Wood column-beam joint structure; lag screw bolts and t-shaped gusset plates and slitted beam members

Info

Publication number: NZ264341A
Application number: NZ26434194A
Authority: NZ
Inventors: Kohei Komatsu
Original assignee: Forestry & Forest Products Res
Priority date: 1994-03-10
Filing date: 1994-08-30
Publication date: 1996-07-26
Also published as: JP2653414B2; AU7155094A; CA2131107A1; AU678839B2; CA2131107C; JPH07252888A

Description

264 34 1 Priority Dato(s): J.o..l5.|..9.frf.

Complete S pacific:? tion Filed: Class: (§). £LQ.^.J&.\.|.af5?jLSS Publication Date: P.O. Journa: No: | Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION WOOD COLUMN-BEAM JOINT STRUCTURE USING LAG SCREW BOLTS We, FORESTRY AND FOREST PRODUCTS RESEARCH INSTITUTE BELONGING TO MINISTRY OF AGRICULTURE, FORESTRY AND FISHERIES a Japanese Company of Matsunosato 1, KukizaJci—machi, InashdJci-gun, Ibaxaki—ken, Japan, hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: PT0520092 (followed by page la) Our Ref: DT203659 26 4 34 WOOD COLUMN-BEAM JOINT STRUCTURE USING LAG SCREW BOLTS BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a joint structure of wood column and wood beam, and more particularly to a joint structure for joining rigidly a column with a beam each having a large sectional area.

Description <?f the Related Act In recent years, large-scale wooden buildings have been constructed. However, sufficient method for realizing a rigid frame structure which does not need walls in both rigid and span directions has not yet been developed.

In order to realize a rigid frame as described above, one method has been developed in which double-end bolts are passed through a column to join a column member tightly with a beam member. However, it is difficult to adopt this method actually because deep sticking of sectional area of the beam member into the side faces of the column member becomes a fatal drawback.

Another method has been also developed in which deformed bars are inserted into a column and beams, and then bided with adhesives. However, this method has such drawbacks that a period of time for curing is needed upon execution and that control of the temperature and humidity is needed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a [(followed by page 2) 2 f> 4 3 4 1 novel wood column-beam joint structure capable of joining a ridge direction with a span direction rigidly at the same time by means of wood, and capable of realizing a two-dimensional rigid frame structure by a timber structure in the same manner as a steel frame construction and a reinforced concrete construction.

It is another object of the present invention to provide a novel wood column-beam joint structure capable of giving a role of a final fixture material to the structure by using laminated materials having large sectional areas, thereby reducing a cost for finishing the inside of a building and securing wide spaces having a large degree of freedom.

According to one aspect of the present invention there is provided a wood column-beam joint structure using lag screw bolts for joining a wood column member and wood beam members by means of lag screw bolts and gusset plates, each of the lag screw bolts consisting of a lag screw section and the bolt sections at its end sections, each of the gusset plates being made of steel plate formed into a T-shape, and having a plurality of through holes at its head section of T-shaped plate by virtue- of which the bolt end sections of the lag screw bolts can be fastened by nuts and a plurality of small holes into which drift-pins are fitted, wherein one end of each of the beam members is provided with a slit into which each of the leg sections of T-shaped plates of the gusset plates are fitted, and small through holes corresponding to the plurality of small holes of each 26 4 34 i of the leg sections of T-shaped plates; and wherein a plurality of the lag screw bolts are arranged side by side and horizontally screwed into the wood column member in such a way that each of bolt end sections thereof are protruded outside the column member; each of the bolt end sections protruded outside the column member are passed through the through holes of each of the head sections of T-shaped plates of the gusset plates and secured to the wood column member by means of nuts; each of the leg sections of T-shaped plates of the gusset plates are fitted into each of the slits of the beam member; and drift-pins for transmitting shearing force are fitted into the small holes of the leg sections of T-shaped plates and small through holes of the beam members corresponding thereto.

In the constitution as described above, a gusset plate comprising two rectangular steel plat.es each having a thickness from ten and several mm to several tens mm got butted against each other so as to, be formed in T-shape and welded with a double bevel groove welding may be preferably used. The leg section of the T-shaped plate is generally fitted vertically into a slit formed in the beam member. The lag screw bolts should support the gusset plate securely at several points. To cope with this, through holes are usually provided at least near the four corner of the head section of the T-shaped plate, and four lag screw bolts passing through these through holes are arranged side by side such that they are screwed into the column, member, However, the number of the lag screw bolts is not limited, and more of the lag screws (usually even number, such as six or eight) may be used to provide sections secured by the lag screw bolts. The lag screw bolt to be used in the present invention varies in accordance with the size of the adopted' column member and the beam member. However, a lag screw bolt which comprises a shaft of a round steel bar having a diameter of about 20 mm to 40 mm threaded, for example, in the form of a lag screw with a root diameter of 2.7 cm, a thread diameter of 3.5 cm and. a thread angle of 60°, and ends sections threaded according to M27 specifications, as an example as described later is generally used. The lag screw bolt to be used is not limited thereto.

In the constitution as described above, one bolt section may be provided at one end of the lag screw bolt to be secured with the gusset plate, thereby joining one beam member with the column member. And, two bolt sections may be provided at both ends of the lag screw bolt to pass through the column member, thereby two beam members are joined with the both ends, respectively. Further, a group of lag screw bolts may be buried in the column member and arranged side by side, and other group of lag screw bolts may also be buried in the column member in such a manner that these two groups of lag screw bolts cross at a right angle, thereby the beam members are joined with one column member in three or four dimensions.

The small holes of the leg section of T-shaped plate into which drift-pins are fitted and the small--holes of the beam member corresponding thereto should be formed in number - 26 capable of fitting a sufficient number of the drift-pins thereinto for bearing a shearing force. As a typical example, a number of these small holes may be preferably formed at equal intervals along circumferences of concentric double circles.

Any type of drift-pin may be used as long as it can bear shearing force between the beam member and the gusset plate. A steel pin having a diameter of 8 mm to 22 mm, preferably 14 mm to 19 mm may be used. The small holes of the leg section of T-shaped plate and the small through holes of the beam member corresponding thereto are formed so as to have diameters for driving the drift-pins to be fitted closely thereinto.

A laminated material or the like, for example, Oregon pine laminated wood may be used as the column member and the beam member to be joined according to the present invention, but they are not limited to this material. For example, a laminated veneer lumber (LVL) and PSL, so-called engineering wood, may be used.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1(a) is a front view of a column member of the present invention seen from the direction of through holes; Fig. 1(b) is a side view of the column member; Fig. 2(a) is a general view of a lag screw bolt of,the present invention; Fig. 2(b) is a partially enlarged view thereof; Fig. 3(a) is a front view of a beam member, of the present invention; 2 6%%4s3;4 Fig. 3(b) is a side view thereof; Fig. 3(c) is a plan view thereof; Fig. 4 shows a condition where four lag screw bolts are screwed in the column member and both ends of the lag screw bolts are protruded beyond both side faces of the column member; Fig. 5(a) is a front view of a gusset plate of the present invention; Fig. 5(b) is a side view thereof seen from a head section of T-shaped plate; Fig. 5(c) is a plan view of the gusset plate; Fig. 6 is a development showing a column-beam joint structure of the present invention in which the column member is joined with the beam members by means of the lag screw bolts and the gusset plates; and Fig. 7 shows outline of a device used for strength test of the column-beam structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A joint structure according to the present invention will be described in further detail by way of embodiment with reference to the accompanying drawings and results of a strength test.

Embodiment 1 Figs. 1 (a) and 1 (b) show a column member 1. In this embodiment, three sheets of Oregon pine laminated lumber 101 to 103 (15 cm x 45 cm) were subjected to the secondary bonding to form the column member 1 having a predetermined shape, i.e. 4 50 mm square and a length of 4,110 mm. Four through holes (pre-holes) 104 each having a diameter of 27 mm were formed at the positions shown in the figures (two of them are positioned at 1401 mm from the end of the column member and the rest of two are 2111 mm from the same, respectively). Fig. 1(a) is a front view of the column member 1 seen from the direction of the through holes, and Fig. 1(b) is a side view thereof.

Figs. 2(a) and 2(b) show a lag screw bolt 2. In this embodiment, the lag screw bolt 2 comprises a shaft 201 threaded in the form of a lag screw having a length corresponding to a width of the column member 1, thread diameter of 3.5 cm, a root diameter of 2.7 cm, a thread angle of 60° and a pitch of 10 mm; and two bolt sections each having a length of 5 cm provided at the ends of the lag screw bolt 2 to protrude beyond the column member 1 when the shaft 201 is screwed in the column member 1. The bolt sections are threaded according to M27 bolt specifications. The lag screw bolts 2 are screwed into the through holes 104 of the column member 1 having a diameter of 27 mm using a torque wrench in such a manner that both ends thereof protrude beyond the column member 1. Fig. 2(a) is a general drawing of the lag screw bolt 2; and Fig. 2(b) is a partially enlarged view of thereof.

Figs. 3(a) to 3(c) show a beam member 3 (2616 mm x 200 mm x 800 mm) made of Oregon pine laminated lumber. About 800 mm length of slit having a thickness of 11 mm and a number of through holes (pre-holes) 302 into which steel drift-pins each having a diameter of 18 mm can be driven 2 6 4 3 4 circumferentially are provided at one end of the beam member 3. Two stepped sections 303 are provided at the corner portions of one end of the beam member 3 in order to secure spaces for fastening gusset plates 4 described later to the end sections, protruded beyond the column member 1, of the lag screw bolts 2 by means of nuts. Fig. 3(a) is a front view of the beam member 3; Fig. 3(b) is a side view thereof; and Fig. 3(c) is a plan view thereof.

Fig. 4 shows a condition where four bolt sections of the lag screw bolt 2 threaded according to M 27 bolt specifications each having length of 5 cm are protruded beyond the both side faces of the column member 1.

Figs. 5(a) to 5(c) show a T-shaped gusset plate 4. The gusset plate 4 comprises a head section of T-shaped plate (end plate) 401 made of steel plate having a rectangular shape of 790 mm height by 200 mm wide and a thickness of 14 mm; and a leg section of T-shaped plate 402 made of steel plate having a rectangular shape of 7 90 mm height by 7 90 mm wide and a thickness of 9 mm which is butt welded with a double bevel groove welding to be fixed to the head section 401. The head section of T-shaped plate 401 has hour through holes 403 each having a diameter of 30 mm at four corners thereof. In the leg section of T-shaped plate, 16 small holes 404 each having a diameter of 18 mm are formed at equal intervals along each of circumferences of the inner and outer concentric circles having radii 260 mm and 323 mm, respectively. Fig. 5(a) is a front view of the.gusset plate 4; Fig. 5(b) is a side view thereof seen from the head 26 4 34 1 section of T-shaped plate; and Fig. 5(c) is a plan view of the gusset plate 4.

Fig. 6 is a development showing a column-bean joint structure of the column member 1 and the beam members 3 as described above by means of the lag screw bolts 2 and the gusset plates 4. In this embodiment, four lag screw bolts are arranged side by side along two crossing dimensions, respectively, to pass through the column 1, and the beam members 3 are jointed to respective ends of the bolts through the gusset plates 4. In other words, the bolt sections 202 of four lag screw bolts 2 screwed in and fixed to the column member 1 are passed through the through holes 403 of the gusset plate 4 to be fastened by means of nuts, thereby fixing the gusset plates to the column member. And, the lag section of T-shaped plate 402 is inserted into the slits 301 of the beam member 3, and then the drift pins each having a diameter of 18 mm are driven into the small holes 404 of the gusset plates 4 and the through holes 302 of the beam member 3 corresponding thereto to fix them, thereby finishing joint of the column member 1 and the beam members 3.

In this embodiment, lower surfaces of ends of the lag screw bolt protruded beyond the column member is covered with a U-shaped fire-resistant covers (laminated material). Strength Test With respect to the column-beam joint structure constituted as described above, test samples 1 to 3 of column-beam crossing were produced. The heights of the beam 2 6 4 5 of these samples were 500 mm, 650 mm, and 800 mm, respectively. These samples were subjected to a strength test (Fig. 7) in which vibration in left and right directions was repeatedly given to the column member with a condition described below. A lower end of the column member and outer ends of the beam members were supported by hinges, respect ively.

Conditions of Test: Amplitude of left and right vibration...20 mm by 20 mm in left and right directions at beginning, and increased with V2 times by V2 times thereafter until 245 mm by 245 mm in left and right directions.

Number of repeat of vibration ... 8 times Form the results of the test, it was revealed that sticking of the head section of T-shaped plate 401 into the side faces of the column did not occur at all in the beginning and that the joint caused remarkably less deformation of the column and the beam compared with a conventional joining method which caused large deformation of the same.

As regards the break of the test samples, in case of the test sample 1 having a height of the beam member of 500 mm, draft-pin joint sections at the beam member were broken In case of the test samples 2 and 3, they were broken in • such a manner that lag screw bolts 2 were pulled out from the column. The proof stresses upon break were remarkably increased compared with a conventional joint method which caused large deformation due to sticking.

C D 4 From the results as described above, it was proved that the column-beam structure having high strength and toughness capable of being easily executed in a construction field and of reducing a initial deformation could be constituted.

The feature of the present invention offers the following advantages: The joint structure causing no sticking of the beam into the side faces of the column and less deformation, and having excellent strength can be provided; The column and the beam each having a large structure can be joined rigidly in a very simple method, both ridge and span directions can be joined rigidly at the same time, and a two-dimensional rigid frame structure which is quite same as a steel frame construction and a reinforced concrete construction can be realized by a timber structure; A cost for finishing the inside of the building constructed with the joint method of the present invention can be reduced and wide spaces having a large degree of freedom can be secured because the constitution material of the laminated materials having large sectional areas perform the role of final fixture materials; and As compared with a joint structure in which deformed bars are inserted into a column and beams, and then bided with adhesives, it is not necessary to secure a period of time of curing for bonding upon execution and to control the temperature and humidity, thereby remarkably reducing a period of time for constructing a building.

Claims

- 12 - WHAT XWE CLAIM IS: - 2 6 4 3M

1. A wood column-beam joint structure using lag screw bolts for joining a wood column member and wood beam members by means of lag screw bolts and gusset plates, each of said lag screw bolts consisting of a lag screw section and the bolt sections at its end sections, each of said gusset plates being made of steel plate formed into a T-shape, and having a plurality of through holes at its head section of T-shaped plate by virtue of which the bolt end sections of said lag screw bolts can be fastened by nuts and a plurality of small holes into which drift-pins are fitted, wherein one end of each of said beam members is provided with a slit into which each of the leg sections of T-shaped plates of said gusset plates are fitted, and small through holes corresponding to said plurality of small holes of each of said leg sections of T-shaped plates, • and wherein a plurality of said lag screw bolts are arranged side by side and horizontally screwed into said wood column member in such a way that each of bolt end sections thereof are protruded outside the column member, each of said bolt end sections protruded outside the column member are passed through the through holes of each of the head sections of T-shaped plates of said gusset plates and secured to the wood column member by means of nuts; each of the leg sections of T-shaped plates of said gusset plates are fitted into each of the slits of said beam member; and drift-pins for transmitting shearing force are fitted into the small holes of the leg sections of T-shaped plates and - 13 - 26 4 3 small through holes of the beam members corresponding thereto.

2 . A wood column-beam joint structure according to claim 1, wherein said bolt section of said lag screw bolt is provided at one end or either end of each of said lag screw bolt .

3 . A wood column-beam joint structure according to claim 1 or 2, wherein said small holes of the leg section of T-shaped plate into which drift-pins are fitted and said small holes of said beam member corresponding thereto are formed at equal intervals along any one of circumferences of a single circle, concentric double circles and concentric triple circles.

4. A wood column-beam joint structure according to any one of claims 1 to 3, wherein said leg section of T-shaped plate is in a plumb position and said head section of T-shaped plate is a rectangular shape and secured in position at least near the four corners thereof by said lag screw bolts and the nuts.

5. A wood column-beam joint structure substantially as herein described with reference to Figures 1-6.

6. A wood column-beam joint structure as claimed in claim 1 and substantially as herein described with reference to FORESTRY AND FOREST PRODUCTS RESEARCH INSTITUTE BELONGING TO MINISTRY OF AGRICULTURE, FORESTRY AND FISHERIES By Its Attorneys BALDWIN, SON & CAREY Figures 1-6.