Structural reinforcement system and reinforcing method at joint between structural members

In a structural reinforcement system of the present invention, a reinforcing material of a bundled fibrous material is positioned spanning a joint between structural members, and then opposite end sections of the reinforcing material are inserted into apertures formed in each of the structural members and fixed in place by anchoring with an adhesive. An angle formed between a center line of each aperture and a line connecting openings of the apertures should preferably ranges between 135.degree. to 160.degree.. The reinforcing material is preferably a bundle of fibers selected from the group consisting of aramid fiber, nylon fiber, carbon fiber, glass fiber, and steel fiber, and the bundle of fibers is impregnated with a resin.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a structural reinforcement system and a
 reinforcing method for reinforcing the joint sections between structural
 members applied in wooden buildings such as between a concrete continuous
 footing and a sill, a concrete continuous footing and a sill and a post, a
 sill and a post, a sill and a brace, a post and a beam, a post and a
 girder, two different beams, a beam and a girder or a girt, or
 alternatively for reinforcing the joint sections between structural
 members or masonry units such as concrete blocks, pre-cast concrete,
 stone, or brick.
 2. Description of the Related Art
 In recent years, the collapse of buildings and concrete block walls and the
 like due to strong earthquakes has become a major problem. For example, a
 particular cause of the collapse of wooden buildings is the portions where
 a sill and a post, a post and a beam, or a beam and a girder are joined
 via a tenon and/or a joint, and cases have been substantiated where the
 vibration of an earthquake has caused the tenon to pull out, or the joint
 to be destroyed.
 As a result, in the recent construction of new wooden buildings, joints
 between members such as sills, posts, braces and beams have been
 reinforced by using various types of mounting materials such as nails,
 bolts, and nuts to attach steel fixtures such as hold down bolts or angle
 plate reinforcing metal struts to the external side, or both sides of the
 structural members.
 However, in the case of the reinforcement of joints in existing buildings,
 use of the structural reinforcement system s described above would require
 the removal of interior finishing of the buildings to expose the joints,
 and consequently the earthquake proofing reinforcement of existing wooden
 buildings using the above structural reinforcement systems has proved to
 be difficult.
 In addition, thought has been given to simplifying the attachment of the
 metal reinforcement fixtures by using nails or screws to attach the
 reinforcement fixtures to the joints from the outside. However, there are
 inherent problems with such a technique, such as a deterioration in
 strength and durability in comparison with a structure using a bolt and
 nut which is fixed from both the inside and the outside, a lack of
 reliability of the reinforcement, and a lack of aesthetic appeal of the
 resulting exterior.
 Furthermore, in the case of a structural reinforcement system using the
 above type of metal reinforcement fixtures, there are also problems of
 durability, as dew condensation will form on the metal reinforcement
 fixtures, resulting in rust and corrosion. Moreover, there is also a
 danger that as a result of the dew condensation generated on the metal
 reinforcement fixtures, the sills, posts, and beams will deteriorate, and
 will invite termite damage.
 Furthermore, in the case where metal reinforcement fixtures are used to fix
 rigidly a joint section, there is a danger that the shock during an
 earthquake will not be absorbed and dispersed, and it will act directly on
 the structural members, resulting in the rupture of the structural
 members.
 SUMMARY OF THE INVENTION
 The present invention takes the above problems into consideration, with an
 object of providing a highly reliable structural reinforcement system and
 reinforcing method for the joint sections of structural members, which is
 easy to install, has excellent durability, and give less damage to the
 structural members, moreover it can also be used in existing buildings.
 In order to achieve the above object, a structural reinforcement system for
 joint sections of structural members of the present invention is a
 structural reinforcement system for reinforcing joints between associated
 structural members wherein a reinforcing material of a bundled fibrous
 material is positioned spanning the joint between the structural members,
 and then opposite end sections of the reinforcing material are inserted
 into apertures respectively formed in the structural members and fixed in
 place by anchoring with an adhesive.
 Because the joint between the structural members is reinforced with a
 reinforcing material of a fibrous material with excellent tensile
 strength, then when vibration resulting from an earthquake or the like is
 applied to the joint, undesirable occurrences such as the joint rupturing
 and the tenon pulling out can be prevented. Consequently, the collapse of
 the buildings or other structures reinforced by this structural members
 can be prevented.
 Furthermore in comparison with reinforcement by metal fixtures, the
 reinforcement using the present invention is able to absorb the shock
 applied to the joints, and release the stresses. In particular, by making
 the fibrous material a twisted type (rope type) or braided type material,
 the shock absorption capability of the material is increased even further.
 Moreover, in contrast to metal fixtures, the reinforcing material is able
 to be cut, enabling the length to be freely adjusted as required by the
 circumstances. In addition, the problem of dew condensation does not
 cause, and rust resulting from condensation cannot occur. Furthermore,
 because dew condensation does not develop, the problems of deterioration
 in the structural members, and termite damage can also be avoided. In
 addition, the fibrous material does not lose the aesthetic appeal of the
 building as shown in the metal fixtures.
 It is also possible to have the entire reinforcing material, or
 alternatively a portion of the reinforcing material impregnated with a
 resin. In those cases where the reinforcing material is a fibrous material
 into which has been impregnated a resin, the fibrous material which makes
 up the reinforcing material can be maintained in a bundled state, thereby
 improving the handling and workability.
 In a reinforcing method for joint sections between structural members
 according to the present invention, apertures are formed in the joined
 structural members, the apertures are filled with an adhesive, and then
 the opposite end sections of a reinforcing material comprising a bundled
 fibrous material are inserted in the apertures and fixed in place by
 anchoring with the adhesive. With this method, the joints between
 structural members can be reinforced with a reinforcing material
 comprising a fibrous material of superior tensile strength. Consequently
 when vibration is applied to a joint during an earthquake or the like,
 undesirable occurrences such as the joint rupturing or the tenon pulling
 out can be prevented. As a result, the collapse of buildings or other
 structures constructed from such structural members can be prevented.
 Furthermore, in comparison with those cases where reinforcement is
 conducted using metal fixture reinforcement, the reinforcement is carried
 out with a reinforcing material which is lightweight, is not bulky, and
 which is easy to handle. Therefore an installation operation which is
 simple and displays excellent operating efficiency can be achieved, and
 the transportation and carrying of the reinforcing material is also easy.
 Moreover, in comparison with metal fixtures, the fibrous reinforcing
 material is more able to absorb any shock applied to the joints of the
 structural members, and disperse the stress, and moreover avoid dew
 condensation problems, meaning rust will not develop. Furthermore, because
 dew condensation does not develop, the problems of deterioration in the
 structural members, and termite damage can also be avoided. Moreover the
 fibrous material does not affect the aesthetic appeal of the building in
 the same way as metal fixtures.
 In terms of fireproofing, the reinforcing material has heat resistant
 characteristics at temperatures above the permissible temperature for
 timber of 260.degree. C., and it is ideally suited for use in fire
 protection construction type external walls. Furthermore, even if the
 anchoring of the reinforcing material by adhesive is carried out during
 winter, the insulating characteristics of timber mean that the temperature
 inside the apertures will not fall too low, and will be maintained at a
 temperature suitable for the curing of the adhesive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 A description, based on the drawings, of embodiments of structural
 reinforcement systems and reinforcing methods for reinforcing the joint
 sections of structural member is as follows according to the present
 invention.
 In FIG. 1, numeral 1 denotes a concrete continuous footing. A sill 2 is
 fixed to the upper surface of the concrete continuous footing 1. A post 3,
 such as a corner post, is fixed vertically on the top surface of the sill
 2.
 A tenon (not shown in the drawing) is formed on the end of the post 3, and
 by engaging the tenon into a mortice (not shown in the drawing) formed in
 the sill 2, the post 3 is joined vertically to the sill 2 in an upright
 state. A structural reinforcement system is attached to the framework of
 the joint between the sill 2 and the post 3.
 Numeral 11 denotes a reinforcing material. The reinforcing material 11 is
 installed in a position spanning the joint (joint section) between the
 post 3 and the sill 2, and in a position spanning the joint between the
 post 3, the sill 2 and the concrete continuous footing 1.
 The reinforcing material 11 is a bundled fibers, and examples of suitable
 fibrous materials with superior tensile strength include either one, or
 two or more, of the materials selected from organic materials such as
 nylon fiber and aramid fiber, inorganic materials such as carbon fiber and
 glass fiber, and metallic fibers such as steel fiber. Furthermore, a
 plurality of fibers can be bundled in parallel to form the reinforcing
 material 11, or alternatively a plurality of fibers can be twisted to form
 a twisted rope type material, or woven to form a braided type material.
 Next is a description of the installation structure of the reinforcing
 material 11, using the reinforcing material fitted across the joint
 between the sill 2 and the post 3 as an example.
 As shown in FIG. 2, open apertures 12 are formed on the surface of the
 structural members of the sill 2 and the post 3. The apertures 12 are
 formed at an angle so that the distance between the apertures increases
 with movement from the aperture openings deeper into each aperture.
 The opposite end sections of the rod shaped reinforcing material 11 are
 inserted into the respective apertures 12, and the inserted reinforcing
 material 11 is then fixed in place inside the apertures 12 with an
 adhesive 13, as shown in FIG. 3.
 The anchored sections 11b, comprising the opposite end sections of the
 reinforcing material, are inserted into the apertures 12, and then they
 are anchored in place with the adhesive 13, bent with respect to a bonded
 section 11a comprising an intermediate portion of the reinforcing material
 11. There are no particular restrictions on the type of adhesive 13 used,
 but single liquid, or double liquid epoxy resin type adhesives are
 effective.
 The bend angle .theta. between the bonded section 11a and the anchored
 sections 11b is set to an obtuse angle of approximately 150.degree.. Any
 angle could be used for the bend angle .theta. between the bonded section
 11a and the anchored sections 11b, but obtuse angles are preferable in
 terms of maximizing strength, with angles between 135 to 160.degree. being
 even more desirable, and angles of approximately 150.degree. being
 particularly suitable. The internal corner of the aperture 12, at the bend
 point between the bonded section 11a and the anchored section 11b, is
 curved, with the corner having been smoothed off.
 There are no restrictions on the thickness of the reinforcing material 11,
 but applicable values for use in a standard house should preferably be
 between 3 to 20 mm, with values between 5 to 13 mm being even more
 desirable. Thickness values within this range result in good workability.
 The diameter of the apertures 12 should preferably be between 2 to 1.2
 times the diameter of the reinforcing material 11, with diameters of 1.5
 to 1.3 times the diameter of the reinforcing material 11 being even more
 desirable. Values within this range result in good workability and good
 anchoring strength by the adhesive 13.
 There are no restrictions on the depth of the apertures 12, but applicable
 values for use in a standard house should preferably be between 60 to 200
 mm, with values between 80 to 140 mm being even more desirable. Depths
 within this range resulted in good anchoring strength (adhesive strength)
 by the adhesive 13, with low cost.
 In the installation of a structural reinforcement system using the
 reinforcing material 11 on the joint between the sill 2 and the post 3,
 first apertures 12 are formed in both the sill 2 and the post 3. Then the
 adhesive 13 is inserted inside the apertures 12. After this the anchoring
 sections 11b of the reinforcing material 11 are inserted in the apertures
 12, and the intermediate bonded section 11a is flattened out into a
 straight line.
 In this manner, by using the joint structural reinforcement system and
 reinforcing method described above, the joints between structural members
 such as the concrete continuous footing 1, the sill 2 and the post 3 are
 reinforced with a reinforcing material 11 comprising a bundled fibrous
 material of superior tensile strength. Therefore when vibration is applied
 to a joint during an earthquake or the like, undesirable situation such as
 the joint rupturing or the tenon pulling out can be prevented. As a
 result, the collapse of buildings or other structures constructed from
 such structural members can be prevented.
 Furthermore, in comparison with the metal fixture reinforcement, the
 present reinforcement is carried out by a reinforcing material with
 lightweight, not bulky, and easy to handle. Therefore, an installation
 operation with simple and excellent operating efficiency is achieved, and
 the transportation and carrying of the reinforcing material is also
 simple. Moreover, in comparison to reinforcement using metal fixtures, the
 fiber reinforced material is able to absorb any shock applied to the
 joints of the structural members, and disperse the stress. In those cases
 where the fibrous material is bundled and then either twisted to form a
 twisted rope type material or woven to produce a braided type material,
 the shock absorbing effect of the reinforcing material 11 is particularly
 large. Furthermore in comparison with metal fixtures, the cutting of a
 reinforcing material 11 comprising bundled fibers is relatively simple,
 and so the length of the reinforcing material 11 can be easily adjusted
 depending on the circumstances.
 In addition, dew condensation will not develop on the reinforcing material
 11, meaning that rust will not develop. Because of no dew condensation
 does not develop, the problems of deterioration in the structural members,
 and termite damage can also be avoided. Moreover the fibrous material does
 not affect the aesthetic appeal of the building in the same way as metal
 fixtures.
 In terms of fireproofing, the reinforcing material 11 shows heat resistant
 characteristics at temperatures above the permissible fire resistant
 temperature for timber of 260.degree. C., and is ideally suited for use in
 fire protection construction type external walls. Furthermore, even if the
 anchoring of the reinforcing material by adhesive is carried out during
 winter, the insulating characteristics of timber shows that the
 temperature inside the apertures will not fall too low, and will be
 maintained at a temperature suitable for the curing of the adhesive.
 Furthermore, by making the bend angle between the bonded section 11a
 comprising the intermediate portion of the reinforcing material 11, and
 the anchored sections 11b which comprise the opposite end sections of the
 reinforcing material which are to be anchored to the structural members,
 an obtuse angle, the amount of shearing force applied to the bend section
 can be reduced, enabling a further increase in the strength supplied by
 the reinforcing material 11. Moreover, by curving the corner of the
 aperture 12 where the reinforcing material 11 is installed, the amount of
 shearing force applied at the corner of the opening of the aperture 12 can
 be dispersed, enabling a further increase in the strength supplied by the
 reinforcing material 11.
 In the example described above, the reinforcing material 11 was a simple
 bundle of a fibrous material, but it is also possible to have a
 reinforcing material 11 wherein the entire or a portion of fibrous
 material bundle, is impregnated with a resin. There are no particular
 restrictions on the types of resin impregnated, but resins such as the
 thermoplastic resin polypropylene and the thermosetting resin polyester
 are particularly suitable.
 When a reinforcing material 11 impregnated with a thermoplastic resin is to
 be inserted in an aperture 12, then the part near the end of the linear
 reinforcing material 11, namely the section which will become the bend
 section, is heated and the resin impregnated in the fibrous material
 softened. If required the intermediate bonded section 11a can also be
 heated and softened.
 In those cases where a thermosetting resin is used as the resin for
 impregnating the reinforcing material 11, the opposite end sections of the
 reinforcing material 11 are heat hardened, and then inserted into the
 apertures 12 and anchored with the adhesive 13, and in those cases where
 the intermediate portion is also impregnated with resin, the intermediate
 portion is then also heat hardened. By using a reinforcing material 11
 comprising a fibrous material which has been impregnated with a resin, the
 fibrous material is maintained in a bundled state, thereby improving the
 handling and workability of the material.
 In addition to the joints between the concrete continuous footing 1 and the
 sill 2, the concrete continuous footing 1 and the sill 2 and the post 3,
 and the sill 2 and the post 3, the structural reinforcement system
 described above can also be applied to joints between other structural
 members, such as between the sill 2 and a brace, the post 3 and a beam and
 a girder, two different beams, or a beam and a girder and a girt, or
 alternatively can be applied to the reinforcement of the joints between
 structural members such as concrete blocks, pre-cast concrete, stone, or
 brick.
 In the structural reinforcement system shown in FIG. 4 and FIG. 5, a
 channel (groove) 14 is formed on the surface of the members 2 and 3 in a
 position corresponding with the location of the bonded section 11a of the
 reinforcing material 11. In this manner, by forming a channel 14 and then
 installing the bonded section 11a inside the channel 14, the protrusion of
 the reinforcing material 11 can be eliminated.
 In such a case, in addition to the adhesive inside the apertures 12, the
 structural members (the sill 2 and the post 3) and the reinforcing
 material 11 can be further bonded together by providing adhesive 13 either
 at the opposite ends of the channel 14, or along the entire length of the
 channel 14.
 The structural reinforcement system shown in FIG. 6, shows a situation
 where plural reinforcing materials 11 in the same direction are provided
 inside a channel 14. It is possible to accommodate plural reinforcing
 materials 11 inside a channel 14 in this manner.
 In the structural reinforcement system shown in FIG. 7, a reinforcing pipe
 15 made of metal or the like is inserted inside an aperture 12, and the
 anchoring section 11b of the reinforcing material 11 is then inserted
 inside the reinforcing pipe 15 and fixed in place with an adhesive 13. By
 using the reinforcing pipe 15, the opening section of the aperture 12 will
 be protected by the reinforcing pipe 15 when a force acts on the
 reinforcing material 11, thereby preventing any damage to the opening
 section of the aperture 12, and enabling the reinforcing material 11 to be
 maintained in a state of good linkage with no slackness in the material.
 The reinforcing pipe 15 itself, is also fixed inside the aperture 12 with
 an adhesive.
 FIG. 8 shows a structural reinforcement system for a joint between a
 concrete continuous footing 1, a sill 2, and a post 3 away from a corner.
 FIG. 9 through FIG. 11 show the use of structural reinforcement systems of
 the present invention adapted for joints between a sill 3 and a beam 21,
 between two different beams 21, and between a sill 2 and a brace 22
 respectively.
 FIG. 12 shows a structural reinforcement system in which the joints between
 a series of blocks 23 are reinforced using a reinforcing material 11 of
 the present invention.
 FIG. 13 shows a structure in which the joints between a series of pre-cast
 concrete slabs 24 are reinforced using a reinforcing material 11 of the
 present invention.
 FIG. 14 shows a structure in which reinforcing material 11 is installed
 spanning a crack in a wall 25 in order to reinforce the structure. In this
 example, the joint (joint section) between the cracked sections of the
 wall 25 is reinforced using the reinforcing material 11.
 EXAMPLES
 The end surfaces of two timber structural members (105 mm.times.105
 mm.times.350 mm) were brought together, and a reinforcing material then
 fixed across the joint between the two structural members under the
 conditions described below. Next, the tensile strength and the stretch of
 the reinforcing material was measured by applying a lengthwise tensile
 load to the structural members.
 EXPERIMENT 1
 Reinforcing material: bundled aramid fibers of diameter 3 mm
 Number of strands of reinforcing material: two (used in a bundled form)
 Aperture angle: 150.degree. and 135.degree.
 Aperture depth: 100 mm
 Aperture diameter: 5 mm
 Adhesive: epoxy resin type adhesive
 EXPERIMENT 2
 Reinforcing material: bundled aramid fiber of diameter 6 mm
 Number of strands of reinforcing material: one
 Aperture angle: 150.degree. and 135.degree.
 Aperture depth: 100 mm
 Aperture diameter: 8 mm
 Adhesive: epoxy resin type adhesive
 Result of Experiment 1
 In the case of an aperture angle of 150.degree.:
 Tensile strength: 8.6 KN Final stretch amount: 5 mm
 In the case of an aperture angle of 135.degree.:
 Tensile strength: 8.4 KN Final stretch amount: 4 mm
 Result of Experiment 2
 In the case of an aperture angle of 150.degree.:
 Tensile strength: 16.2 KN Final stretch amount: 12 mm
 In the case of an aperture angle of 135.degree.:
 Tensile strength: 14.7 KN Final stretch amount: 10 mm