EP0279675B1 - Insert assembly for use in a concrete structure - Google Patents
Insert assembly for use in a concrete structure Download PDFInfo
- Publication number
- EP0279675B1 EP0279675B1 EP88301377A EP88301377A EP0279675B1 EP 0279675 B1 EP0279675 B1 EP 0279675B1 EP 88301377 A EP88301377 A EP 88301377A EP 88301377 A EP88301377 A EP 88301377A EP 0279675 B1 EP0279675 B1 EP 0279675B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- insert
- insert member
- intermediate portion
- tapered
- assembly according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000919 ceramic Substances 0.000 claims description 11
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- 229910010293 ceramic material Inorganic materials 0.000 claims description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000004873 anchoring Methods 0.000 description 3
- 230000004323 axial length Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 241000486661 Ceramica Species 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 229910003465 moissanite Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000009751 slip forming Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/38—Connections for building structures in general
- E04B1/388—Separate connecting elements
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/38—Connections for building structures in general
- E04B1/41—Connecting devices specially adapted for embedding in concrete or masonry
- E04B1/4114—Elements with sockets
- E04B1/4121—Elements with sockets with internal threads or non-adjustable captive nuts
Definitions
- This invention relates to an improvement in an insert assembly which is used for mounting or securing various appliances or equipments onto a concrete surface.
- an insert member which is threadedly matable with a bolt member, is embedded within the concrete structure in order to mount various equipments onto the concrete surface.
- This kind of insert member is generally made of a metal such as steel and the like, and has a configuration such that an annual ridge or a laterally expanded portion is provided to increase the contact area of the insert member which contacts the concrete, enhancing the insert member's anchoring performance to the concrete.
- this conventional insert member is made of metal, it tends to have an inconveniently heavy weight to handle, and also tends to corrode in a rather short period.
- the corrosion of the insert member causes the deterioration of not only the insert member itself but also of the concrete surrounding the insert member.
- coloured plastic caps and the like attachable to the insert members are required to distinguish the insert members for a particular conduit from other insert members.
- Insert members made of synthetic resin may solve the cost problem, however, it is not refractory and, this time, a problem with the insert member's yield strength would arise.
- the plastic insert member has a neck-like portion, the potential of a crack or rupture would be increased because of stress concentration to the neck-like portion.
- FIG. 1 shows an example of the insert member prepared according to the disclosure of this application.
- This insert member 10 is of a truncated conical configuration and has a threaded hole 12 formed along the center axis of the insert member 10.
- the smaller end face 14 of the insert member 10 is exposed so that a bolt member 20 can be screwed into the threaded hole 12.
- the bolt member 20 is, for example, a conventional bolt including a threaded distal end portion 24 and a laterally expanded head portion (not shown).
- the threaded hole 12 of the insert member 10 opens not only to the smaller end face 14 but also to the larger end face 16 of the insert member 10 so as to enable the bolt member 20 to be screwed in the hole 12 as far as the distal end 24 of the bolt member 20 reaches to the level of the larger end face 16.
- This insert member is refractory, and, because of its improved configuration, it has less potential to undergo a stress concentration than conventional insert members.
- a lid member 22 serving as a water stop must be fitted in the opening at the larger end face 16 to prevent the water in the concrete from exuding through the hole 12, the bolt member 20 is in practice not allowed to be screwed so deeply as might be expected.
- FR-A-1,561,627 discloses an insert assembly for use in a concrete structure for mounting equipment onto a concrete surface, the insert assembly comprising: an insert member which is suitable for being embedded in the concrete structure; and a bolt member threadedly matable with the insert member and arranged to be anchored to and project from the concrete surface when the bolt member is mated with the insert member embedded in the concrete structure, said insert member having a tapered intermediate portion the tapered intermediate portion having an external tapered surface which is inclined outwardly with respect to the longitudinal axis (X) of the insert member towards one end of said tapered intermediate portion and having a threaded through hole which extends along said longitudinal axis past said end of said tapered intermediate portion into an end wall portion which is integrally joined to said end of said tapered intermediate portion and can receive the threaded end portion of the bolt member, said threaded through hole being closed by an end wall of said end wall portion and said end wall portion having a transverse outer size not larger than that of said end of the insert member.
- the present invention provides an insert assembly as disclosed in FR-A-1,561,627, characterised in that the insert member is made of a ceramic material and the end wall portion is tapered away from said one end in the opposite sense to the taper of said intermediate portion.
- the bolt member is allowed to be screwed in the threaded hole until the distal end of the bolt member reaches or advances past the junction of the tapered end wall portion and tapered intermediate portion of the insert member without damaging the watertightness of the insert member. Therefore, no axial tensile stress but rather an axial compressive stress is induced in the insert member. Accordingly, this insert member is capable of avoiding a crack or rupture due to a tensile stress, and shows a satisfactory rupture strength against the axial load applied to the bolt member.
- the ceramic of which the insert member is made is an alumina ceramica silicon carbide ceramic or a silicon nitride ceramic.
- the tapered surface of the intermediate portion of the insert member may for example be straight in axial cross-section.
- the inclination angle of the tapered surface of the intermediate portion with respect to the longitudinal axis preferably, is not less than 1° and not greater than 45°.
- the tapered intermediate portion may be of a truncated conical configuration, a truncated polygonal pyramidal configuration or a truncated elliptic conical configuration, for example.
- the tapered surface of the intermediate portion of the insert member may be convexly curved in its axial cross section, for example.
- the end wall portion may taper from its inner face to its outer face.
- FIGS. 2 to 7 the same parts as those in FIG. 1 are designated by the same reference numerals, and descriptions thereof will be omitted.
- FIG. 2 illustrate an insert assembly according to the present invention, in which reference numeral 30 designates a ceramic insert member adapted to be embedded in a concrete structure.
- This insert member 30 consists of three portions, namely, an intermediate portion (hereinafter referred to as an insert body) 32 of a truncated conical configuration, a hollow cylindrical guide portion 34 coaxially and integrally joined to the smaller end of the insert body 32 and an end wall portion 36 integrally joined to the larger end 33 (which is shown by the phantom line) of the insert body 32.
- the insert body 32 has a threaded hole 12 formed along the center axis X thereof.
- the hollow 38 of the guide portion 34 is aligned and communicated with the threaded hole 12 of the insert body 32 to allow a bolt member 20 to be screwed in the threaded hole 12 therethrough.
- the end wall portion 36 is of a truncated conical configuration of which larger end is coaxially connected to the larger end 33 of the insert body 32.
- the diameter of the larger end of the end wall portion 36 in FIG. 2 is generally equal to that of the insert body 32, however, the former may be smaller than the latter.
- the end wall portion 36 has a supplementary threaded hole 40 formed in the inner face thereof. This supplementary hole 40 is aligned and communicated with the threaded hole 12 of the insert body 32 to receive the distal end portion of the bolt member 20.
- the internal thread 42 of the supplementary hole 40 is continuously formed from the internal thread 44 of the threaded hole 12, that is, the major and minor diameters of the thread 42 are equal to those of the thread 44, and also the leads of the threads 42 and 44 are equal to each other.
- the tapered side face 46 of the insert body 32 is inclined at an angle ⁇ with respect to the longitudinal axis X of the insert member 30.
- the angle ⁇ i.e., the cone generating angle of the insert body 32 is not less than 1° and not greater than 45°, and preferably in the range of 15° to 30°. Below 1°, the resultant insert member 30 is not expected to have a satisfactory anchoring performance to the concrete structure, whereas, at 45° and above, when an axial load is applied to the bolt member 20 mated with the insert member 30, there is a potential of a tensile stress being induced in the insert body 32, particularly, in the larger end portion of the body 32. The best rupture strength of the insert body 32 is obtained when the angle ⁇ is 15° to 30°.
- the entire tube wall of the guide portion 34 has a uniform thickness, and the length L2 of the guide portion 34 is determined regarding the rupture strength of the entire insert member 30.
- a mold made of a rubber substance and having an internal configuration which fits around the insert member 30 is prepared.
- a threaded core member such as a bolt substantially equivalent to the bolt member 20 is coaxially fixed inside the mold.
- Powdery material for ceramics such as Al2O3, SiC and Si3N4, having a particle size of about 20 to 30 ⁇ m is filled within the mold.
- the air is eliminated from the inside of the mold, and thereafter, hydraulic pressure of 9.81 ⁇ 1010 N to 2.94 ⁇ 1011 N (1,000 to 3,000 t/cm2) is applied on the mold, forming a compact out of the powdery material.
- the mold is removed from the resultant compact, and then the core member is unscrewed from the compact. Lastly, the compact is sintered at a temperature of about 1,700°C, resulting in the ceramic insert member 30 shown in FIG. 2.
- the preparing of the insert member is simple and easy, and moreover, the inclination angle ⁇ of the insert body 32 which is from 1° to 45° is convenient for preventing any air spaces from being produced in the insert member during the preparation process. Accordingly, it is expected to efficiently manufacture high quality insert members with excellent dimensional accuracy.
- the insert member 30 thus prepared is embedded, as shown in FIG. 2, in a concrete structure 18 to mount different equipments onto the surface 26 of the concrete structure.
- the insert member 30 is detachably attached to the inner surface of a form for concrete placing, and then concrete is placed inside the form.
- the attachment of the insert member 30 onto the form is achieved by fixing a projection member on the inner surface of the form and by firmly fitting the projection member in the hollow 38 of the guide portion 34.
- the removal of the form after the hardening of the concrete results in the embedding of the insert member 30 in such a manner that the free end of the guiding portion 34 is exposed.
- the bolt member 20 is threadedly engaged with the insert member 30 in mounting or securing an appliance, e.g., a gas conduit to the concrete surface 26, in other words, the appliance can be secured to the concrete surface 26 by means of the bolt member 20 screwed into the threaded hole 12 of the insert body 32 through the hollow 38 of the guide portion 34.
- an appliance e.g., a gas conduit to the concrete surface 26
- the appliance can be secured to the concrete surface 26 by means of the bolt member 20 screwed into the threaded hole 12 of the insert body 32 through the hollow 38 of the guide portion 34.
- the bolt member 20 thus securing the appliance on the concrete surface, particularly when it serves as a hanging bolt, is usually subjected to an axial load which urges the bolt member 20 in a direction indicated by arrow C.
- This axial load is transmitted to the concrete structure 18 via the tapered side face 46 of the insert body 32, whereby the reaction force is applied uniformly to the conical side face 46 by the concrete structure 18.
- the bolt member 20 since the bolt member 20 is engaged with the insert member 30 as deeply as the distal end 24 reaches or proceeds over the larger end 33 of the insert body 32, no axial tensile stress but an axial compressive stress is induced in the insert member 30.
- this ceramic insert member 30 can avoid a crack or rupture due to a tensile stress, and shows a satisfactory rupture strength against the axial load applied to the bolt member 20. Furthermore, because of the wedge-like configuration of the insert body 32, the more load the bolt member 20 is subjected to, the more firmly the insert member 30 contacts the concrete structure 18. The result is that the insert member 30 in connection with the concrete structure 18 shows an excellent anchoring performance.
- the bolt member 20 may be advanced or drawn back as long as the distal end 24 of the bolt member 20 is within the supplementary hole 40. That is, in this insert assembly, it is enabled, without bringing the distal end 24 of the bolt member 20 to a position halfway in the threaded hole 12, to adjust the length of the projecting portion 50 to a length of L3 to L3 + dL, where dL is equal to the length L4 of the supplementary threaded hole 40 (see FIG. 2).
- FIG. 4 illustrates a modified form of the insert member in FIG. 2, in which a cylindrical guide portion 54 is separately formed from the remainder of the insert member 52 and the guide portion 54 is detachably connected to the smaller end 56 of an insert body 58. More specifically, the threaded hole 12 is provided at its opening with an engaging section 60 having a larger inner diameter than the remainder of the threaded hole 12, and one of the opposite end sections of the guide portion 54 is fitted in the engaging section 60.
- the distance S between the concrete surface 26 and the insert body 58 it is possible to adjust the distance S between the concrete surface 26 and the insert body 58 by connecting the guide portions of different lengths to the insert body 58.
- FIG. 5 shows another modified form of the insert member in FIG. 2, in which an insert body 62 is tapered toward a guide portion 64 in such a manner that the tapered side face 66 thereof in an axial cross section is convexly curved.
- Reference numeral 68 designates a recesse formed in the side face of the insert member 70 to avoid rotational movement of the insert member 70 when it is embedded in the concrete.
- the reaction force to be exerted on the tapered side face 66 by the concrete structure 18 reduces gradually toward the larger end of the insert body 62 whereby, when the bolt member 20 is not screwed in the threaded hole 12 so deeply as the distal end 24 comes into the supplementary hole 40, the tensile stress to be induced in the larger end portion of the insert body 62 is considerably less than that to be induced in the insert body 32 shown in FIG. 2.
- the insert bodies 32, 58 and 62 and the end wall portion 36 are of truncated conical configurations, they may be of truncated polygonal pyramidal configurations or of truncated elliptic conical configurations. In such configurations, the insert members are enabled to prevent rotational movement when they are embedded in the concrete. Furthermore, instead of the end wall portion 36, an end wall portion of a cylindrical configuration may be employed. This cylindrical end wall portion must have an outer diameter smaller than that of the larger end of the insert body.
- insert members in the preceding embodiments may be colored during their preparation in order to distinguish themselves from other insert members used for different purposes. More specifically, when the insert members for different conduits, that is, for instance, an electric cable conduit, a gas conduit, a water conduit and an air conduit, are colored differently, securing operation for each conduit onto the concrete surface is made efficient and effective, and mistakes in securing operation is reduced.
- This test insert member 30 was embedded in the concrete structure 18 as shown in FIG. 6.
- a steel tension bar 72 having a threaded end portion is threadedly engaged with the test member 30.
- Axial tensile load was applied to the tension bar 72 by means of a ram chair 74 and jack 76 fixed above the test member 30, and was increased until any one of the test member 30, tension bar 72 and concrete structure 18 was broken.
- the tensile load applied to the tension bar 72 was determined by a load cell 78 which was operatively connected to the jack 76. The result was that the concrete structure 18 was broken as shown in FIG.
- This value of the determined tensile load Pb i.e., the compressive load applied to the test insert member upon the destruction of the concrete structure 18 is shown in Table 1 with the design load Pd of the insert member.
- the design load Pd of the test insert member is defined by the same formula given in Example 1.
- the breaking load of the test insert members is substantially greater than the design load thereof, that is, the insert member according to the present invention has excellent rupture strength.
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Description
- This invention relates to an improvement in an insert assembly which is used for mounting or securing various appliances or equipments onto a concrete surface.
- It is not possible to weld metal members such as steel plates and brackets directly to the surface of a concrete structure such as a concrete building, bridge, dam, retaining wall, breakwater and the like. For this reason, an insert member which is threadedly matable with a bolt member, is embedded within the concrete structure in order to mount various equipments onto the concrete surface. This kind of insert member is generally made of a metal such as steel and the like, and has a configuration such that an annual ridge or a laterally expanded portion is provided to increase the contact area of the insert member which contacts the concrete, enhancing the insert member's anchoring performance to the concrete. Because this conventional insert member is made of metal, it tends to have an inconveniently heavy weight to handle, and also tends to corrode in a rather short period. The corrosion of the insert member causes the deterioration of not only the insert member itself but also of the concrete surrounding the insert member. Furthermore, when a plurality of such insert members are used at the same time for mounting different conduits, that is, for example, an electric cable conduit, a gas conduit, a water conduit and a conduit for air conditioning, coloured plastic caps and the like attachable to the insert members are required to distinguish the insert members for a particular conduit from other insert members. These plastic caps, however, are costly and are not refractory, therefore, it is preferable not to use a large number of them. Insert members made of synthetic resin may solve the cost problem, however, it is not refractory and, this time, a problem with the insert member's yield strength would arise. In particular, when the plastic insert member has a neck-like portion, the potential of a crack or rupture would be increased because of stress concentration to the neck-like portion.
- To solve the problems mentioned above, the inventors have proposed an insert member made of ceramics in Japanese Patent Application No. sho 60-282465. FIG. 1 shows an example of the insert member prepared according to the disclosure of this application. This
insert member 10 is of a truncated conical configuration and has a threadedhole 12 formed along the center axis of theinsert member 10. Upon the embedding of theinsert member 10 in theconcrete structure 18, thesmaller end face 14 of theinsert member 10 is exposed so that abolt member 20 can be screwed into the threadedhole 12. Thebolt member 20 is, for example, a conventional bolt including a threadeddistal end portion 24 and a laterally expanded head portion (not shown). The threadedhole 12 of theinsert member 10 opens not only to thesmaller end face 14 but also to thelarger end face 16 of theinsert member 10 so as to enable thebolt member 20 to be screwed in thehole 12 as far as thedistal end 24 of thebolt member 20 reaches to the level of thelarger end face 16. This insert member is refractory, and, because of its improved configuration, it has less potential to undergo a stress concentration than conventional insert members. However, since alid member 22 serving as a water stop must be fitted in the opening at thelarger end face 16 to prevent the water in the concrete from exuding through thehole 12, thebolt member 20 is in practice not allowed to be screwed so deeply as might be expected. In particular, when it is required to adjust the length of that portion of thebolt member 20 protruding from the concrete surface, it is not even possible to bring thedistal end 24 into as deep contact as it has with the lid member 22 (see the phantom line in FIG. 1) but only to bring it halfway into the threadedhole 12. Consequently, when an axial load urging thebolt member 20 in the direction indicated by arrow B is exerted on thebolt member 20, an axial tensile stress tends to be induced in that portion of theinsert member 10 near the larger end, that is, the portion where thebolt member 20 is not inserted. This occurrence of tensile stress in the ceramic insert member is undesirable, since its tensile strength is less than its compressive strength. - FR-A-1,561,627 discloses an insert assembly for use in a concrete structure for mounting equipment onto a concrete surface, the insert assembly comprising: an insert member which is suitable for being embedded in the concrete structure; and a bolt member threadedly matable with the insert member and arranged to be anchored to and project from the concrete surface when the bolt member is mated with the insert member embedded in the concrete structure, said insert member having a tapered intermediate portion the tapered intermediate portion having an external tapered surface which is inclined outwardly with respect to the longitudinal axis (X) of the insert member towards one end of said tapered intermediate portion and having a threaded through hole which extends along said longitudinal axis past said end of said tapered intermediate portion into an end wall portion which is integrally joined to said end of said tapered intermediate portion and can receive the threaded end portion of the bolt member, said threaded through hole being closed by an end wall of said end wall portion and said end wall portion having a transverse outer size not larger than that of said end of the insert member. However the insert member is made of plastic.
- The present invention provides an insert assembly as disclosed in FR-A-1,561,627, characterised in that the insert member is made of a ceramic material and the end wall portion is tapered away from said one end in the opposite sense to the taper of said intermediate portion.
- In the insert assembly of the invention, the bolt member is allowed to be screwed in the threaded hole until the distal end of the bolt member reaches or advances past the junction of the tapered end wall portion and tapered intermediate portion of the insert member without damaging the watertightness of the insert member. Therefore, no axial tensile stress but rather an axial compressive stress is induced in the insert member. Accordingly, this insert member is capable of avoiding a crack or rupture due to a tensile stress, and shows a satisfactory rupture strength against the axial load applied to the bolt member.
- It is preferred that the ceramic of which the insert member is made is an alumina ceramica silicon carbide ceramic or a silicon nitride ceramic.
- The tapered surface of the intermediate portion of the insert member may for example be straight in axial cross-section. The inclination angle of the tapered surface of the intermediate portion with respect to the longitudinal axis, preferably, is not less than 1° and not greater than 45°. The tapered intermediate portion may be of a truncated conical configuration, a truncated polygonal pyramidal configuration or a truncated elliptic conical configuration, for example.
- Alternatively, the tapered surface of the intermediate portion of the insert member may be convexly curved in its axial cross section, for example.
- The end wall portion may taper from its inner face to its outer face.
- Further preferred features are defined in the dependent claims.
- In the drawings:
- FIG. 1 is a side-elevational view partly in section of a conventional insert assembly;
- FIG. 2 is an axial cross-sectional view of an insert assembly according to the present invention;
- FIG. 3 is a side-elevational view partly in section of an insert member in FIG. 2;
- FIG. 4 is an axial cross-sectional view of a modified form of the insert member in FIG. 2;
- FIG. 5 is a side-elevational view partly in section of another modified form of the insert member in FIG. 2;
- FIG. 6 is a schematically side-elevational view partly in section of equipments and a concrete structure used for breaking tests given to test insert members; and
- FIG. 7 is a cross-sectional view of the concrete structure in which an insert member is embedded, showing the result of the breaking tests;
- Referring now to FIGS. 2 to 7, the same parts as those in FIG. 1 are designated by the same reference numerals, and descriptions thereof will be omitted.
- FIG. 2 illustrate an insert assembly according to the present invention, in which
reference numeral 30 designates a ceramic insert member adapted to be embedded in a concrete structure. Thisinsert member 30 consists of three portions, namely, an intermediate portion (hereinafter referred to as an insert body) 32 of a truncated conical configuration, a hollowcylindrical guide portion 34 coaxially and integrally joined to the smaller end of theinsert body 32 and anend wall portion 36 integrally joined to the larger end 33 (which is shown by the phantom line) of theinsert body 32. Theinsert body 32 has a threadedhole 12 formed along the center axis X thereof. The hollow 38 of theguide portion 34 is aligned and communicated with the threadedhole 12 of theinsert body 32 to allow abolt member 20 to be screwed in the threadedhole 12 therethrough. Theend wall portion 36 is of a truncated conical configuration of which larger end is coaxially connected to thelarger end 33 of theinsert body 32. The diameter of the larger end of theend wall portion 36 in FIG. 2 is generally equal to that of theinsert body 32, however, the former may be smaller than the latter. Theend wall portion 36 has a supplementary threadedhole 40 formed in the inner face thereof. Thissupplementary hole 40 is aligned and communicated with the threadedhole 12 of theinsert body 32 to receive the distal end portion of thebolt member 20. Theinternal thread 42 of thesupplementary hole 40 is continuously formed from theinternal thread 44 of the threadedhole 12, that is, the major and minor diameters of thethread 42 are equal to those of thethread 44, and also the leads of thethreads - As shown in FIG. 3, the
tapered side face 46 of theinsert body 32 is inclined at an angle ϑ with respect to the longitudinal axis X of theinsert member 30. The angle ϑ, i.e., the cone generating angle of theinsert body 32 is not less than 1° and not greater than 45°, and preferably in the range of 15° to 30°. Below 1°, theresultant insert member 30 is not expected to have a satisfactory anchoring performance to the concrete structure, whereas, at 45° and above, when an axial load is applied to thebolt member 20 mated with theinsert member 30, there is a potential of a tensile stress being induced in theinsert body 32, particularly, in the larger end portion of thebody 32. The best rupture strength of theinsert body 32 is obtained when the angle ϑ is 15° to 30°. - To maintain the proper rupture strength of the
insert member 30, it is preferred that the tube wall of theinsert body 32 at its smaller end has a thickness T defined by the following formula:
where k is a constant in the range of 4 to 5, and H is the height of thethread 44 formed instead thehole 12. More specifically, the tube wall's thickness T of theinsert body 32 at its smaller end is preferred to be about four to five times thicker than the height H of thethread 44. According to this relationship between the thickness T and the height H as well as the length L₁ of theinsert body 32 and the diameter D of thelarger end 33 of theinsert body 32, the inclination angle ϑ is concretely determined. The entire tube wall of theguide portion 34 has a uniform thickness, and the length L₂ of theguide portion 34 is determined regarding the rupture strength of theentire insert member 30. - The process for preparing the insert member mentioned above will now be described. First, a mold made of a rubber substance and having an internal configuration which fits around the
insert member 30 is prepared. Then, a threaded core member such as a bolt substantially equivalent to thebolt member 20 is coaxially fixed inside the mold. Powdery material for ceramics, such as Al₂O₃, SiC and Si₃N₄, having a particle size of about 20 to 30 µm is filled within the mold. The air is eliminated from the inside of the mold, and thereafter, hydraulic pressure of 9.81 × 10¹⁰ N to 2.94 × 10¹¹ N (1,000 to 3,000 t/cm²) is applied on the mold, forming a compact out of the powdery material. The mold is removed from the resultant compact, and then the core member is unscrewed from the compact. Lastly, the compact is sintered at a temperature of about 1,700°C, resulting in theceramic insert member 30 shown in FIG. 2. As described above, the preparing of the insert member is simple and easy, and moreover, the inclination angle ϑ of theinsert body 32 which is from 1° to 45° is convenient for preventing any air spaces from being produced in the insert member during the preparation process. Accordingly, it is expected to efficiently manufacture high quality insert members with excellent dimensional accuracy. - The
insert member 30 thus prepared is embedded, as shown in FIG. 2, in aconcrete structure 18 to mount different equipments onto thesurface 26 of the concrete structure. In order to embed theinsert member 30, theinsert member 30 is detachably attached to the inner surface of a form for concrete placing, and then concrete is placed inside the form. The attachment of theinsert member 30 onto the form is achieved by fixing a projection member on the inner surface of the form and by firmly fitting the projection member in the hollow 38 of theguide portion 34. The removal of the form after the hardening of the concrete results in the embedding of theinsert member 30 in such a manner that the free end of the guidingportion 34 is exposed. Thebolt member 20 is threadedly engaged with theinsert member 30 in mounting or securing an appliance, e.g., a gas conduit to theconcrete surface 26, in other words, the appliance can be secured to theconcrete surface 26 by means of thebolt member 20 screwed into the threadedhole 12 of theinsert body 32 through the hollow 38 of theguide portion 34. Upon the engagement of thebolt member 20, since theend wall portion 36 seals thelarger end 33 of theinsert body 32 and also since the supplementary threadedhole 40 is provided in theend wall portion 36, thebolt member 20, as shown in FIG. 2, is allowed to be screwed in the threadedhole 12 until itsdistal end 24 reaches or advances over thelarger end 33 of theinsert body 32 without damaging the watertightness of theinsert member 30. - The
bolt member 20 thus securing the appliance on the concrete surface, particularly when it serves as a hanging bolt, is usually subjected to an axial load which urges thebolt member 20 in a direction indicated by arrow C. This axial load is transmitted to theconcrete structure 18 via the tapered side face 46 of theinsert body 32, whereby the reaction force is applied uniformly to the conical side face 46 by theconcrete structure 18. However, since thebolt member 20 is engaged with theinsert member 30 as deeply as thedistal end 24 reaches or proceeds over thelarger end 33 of theinsert body 32, no axial tensile stress but an axial compressive stress is induced in theinsert member 30. Therefore, thisceramic insert member 30 can avoid a crack or rupture due to a tensile stress, and shows a satisfactory rupture strength against the axial load applied to thebolt member 20. Furthermore, because of the wedge-like configuration of theinsert body 32, the more load thebolt member 20 is subjected to, the more firmly theinsert member 30 contacts theconcrete structure 18. The result is that theinsert member 30 in connection with theconcrete structure 18 shows an excellent anchoring performance. - When the length of that
portion 50 of thebolt member 20 projecting from theconcrete surface 26 must be adjusted due to a different thickness of the material such as steel plate to be secured, thebolt member 20 may be advanced or drawn back as long as thedistal end 24 of thebolt member 20 is within thesupplementary hole 40. That is, in this insert assembly, it is enabled, without bringing thedistal end 24 of thebolt member 20 to a position halfway in the threadedhole 12, to adjust the length of the projectingportion 50 to a length of L₃ to L₃ + dL, where dL is equal to the length L₄ of the supplementary threaded hole 40 (see FIG. 2). - FIG. 4 illustrates a modified form of the insert member in FIG. 2, in which a cylindrical guide portion 54 is separately formed from the remainder of the
insert member 52 and the guide portion 54 is detachably connected to thesmaller end 56 of aninsert body 58. More specifically, the threadedhole 12 is provided at its opening with an engagingsection 60 having a larger inner diameter than the remainder of the threadedhole 12, and one of the opposite end sections of the guide portion 54 is fitted in the engagingsection 60. In this construction, depending on the thickness of theconcrete structure 18 in which theinsert member 52 is to be embedded, it is possible to adjust the distance S between theconcrete surface 26 and theinsert body 58 by connecting the guide portions of different lengths to theinsert body 58. - FIG. 5 shows another modified form of the insert member in FIG. 2, in which an
insert body 62 is tapered toward aguide portion 64 in such a manner that the tapered side face 66 thereof in an axial cross section is convexly curved.Reference numeral 68 designates a recesse formed in the side face of theinsert member 70 to avoid rotational movement of theinsert member 70 when it is embedded in the concrete. In this construction, the reaction force to be exerted on the tapered side face 66 by theconcrete structure 18 reduces gradually toward the larger end of theinsert body 62 whereby, when thebolt member 20 is not screwed in the threadedhole 12 so deeply as thedistal end 24 comes into thesupplementary hole 40, the tensile stress to be induced in the larger end portion of theinsert body 62 is considerably less than that to be induced in theinsert body 32 shown in FIG. 2. - Although in the foregoing embodiments, the
insert bodies end wall portion 36 are of truncated conical configurations, they may be of truncated polygonal pyramidal configurations or of truncated elliptic conical configurations. In such configurations, the insert members are enabled to prevent rotational movement when they are embedded in the concrete. Furthermore, instead of theend wall portion 36, an end wall portion of a cylindrical configuration may be employed. This cylindrical end wall portion must have an outer diameter smaller than that of the larger end of the insert body. - In addition, the insert members in the preceding embodiments may be colored during their preparation in order to distinguish themselves from other insert members used for different purposes. More specifically, when the insert members for different conduits, that is, for instance, an electric cable conduit, a gas conduit, a water conduit and an air conduit, are colored differently, securing operation for each conduit onto the concrete surface is made efficient and effective, and mistakes in securing operation is reduced.
- Breaking tests given to the insert members are now described hereunder.
- A test insert member equivalent to the foregoing first embodiment shown in FIG. 2, having 50 mm axial length and 25 mm outer diameter at the larger end portion, was prepared. This
test insert member 30 was embedded in theconcrete structure 18 as shown in FIG. 6. Asteel tension bar 72 having a threaded end portion is threadedly engaged with thetest member 30. Axial tensile load was applied to thetension bar 72 by means of aram chair 74 andjack 76 fixed above thetest member 30, and was increased until any one of thetest member 30,tension bar 72 andconcrete structure 18 was broken. The tensile load applied to thetension bar 72 was determined by aload cell 78 which was operatively connected to thejack 76. The result was that theconcrete structure 18 was broken as shown in FIG. 7 when a tensile load of 23.4 KN (2,390 kg) was applied to thetension bar 72. This result means that thetest insert member 30 was subjected mainly to a compression, and that the breaking load of thetest insert member 30 is more than 23.4 kN (2,390 kg). This value of the determined tensile load Pb, i.e., the compressive load applied to the test insert member upon the destruction of theconcrete structure 18 is shown in Table 1 with the design load Pd of theinsert member 30. -
- A test insert member equivalent to the foregoing modified form shown in FIG. 4, having 50 mm entire axial length, 25 mm outer diameter at the larger end portion and 15 mm axial length of the guide portion, was prepared. A breaking test the same as in Example 1 was given to this test insert member. The result was that the
concrete structure 18 was broken in the same manner as shown in FIG. 7 when a tensile load of 21.3 kN (2,179 kg) was applied to thetension bar 72. This result means that the test insert member was subjected mainly to a compression, and that the breaking load of the test insert member,is more than 21.3 kN (2,170 kg). This value of the determined tensile load Pb, i.e., the compressive load applied to the test insert member upon the destruction of theconcrete structure 18 is shown in Table 1 with the design load Pd of the insert member. The design load Pd of the test insert member is defined by the same formula given in Example 1. - As shown in Table 1, it will be understood that the breaking load of the test insert members is substantially greater than the design load thereof, that is, the insert member according to the present invention has excellent rupture strength.
Claims (11)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1987023744U JPS63132001U (en) | 1987-02-20 | 1987-02-20 | |
JP23744/87 | 1987-02-20 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0279675A1 EP0279675A1 (en) | 1988-08-24 |
EP0279675B1 true EP0279675B1 (en) | 1991-11-06 |
Family
ID=12118818
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP88301377A Expired - Lifetime EP0279675B1 (en) | 1987-02-20 | 1988-02-18 | Insert assembly for use in a concrete structure |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0279675B1 (en) |
JP (1) | JPS63132001U (en) |
KR (1) | KR950011054B1 (en) |
DE (1) | DE3865982D1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2591747B (en) * | 2020-02-04 | 2022-03-02 | Ischebeck Titan Ltd | Anchor assembly |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3418781A (en) * | 1967-01-12 | 1968-12-31 | Cleveland Trencher Co | Bolt anchor for concrete |
CH500388A (en) * | 1967-04-05 | 1970-12-15 | Aackersberg Mortensen | Dowels for setting in concrete |
JPS5354383Y2 (en) * | 1974-07-31 | 1978-12-26 | ||
US3982363A (en) * | 1974-10-18 | 1976-09-28 | Ddk Investments, Ltd. | Frangible insert |
US4368606A (en) * | 1979-07-31 | 1983-01-18 | Sanyo Industries, Ltd. | Socket means for embedment in a concrete slab |
-
1987
- 1987-02-20 JP JP1987023744U patent/JPS63132001U/ja active Pending
-
1988
- 1988-02-18 DE DE8888301377T patent/DE3865982D1/en not_active Expired - Fee Related
- 1988-02-18 EP EP88301377A patent/EP0279675B1/en not_active Expired - Lifetime
- 1988-02-19 KR KR1019880001732A patent/KR950011054B1/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
KR950011054B1 (en) | 1995-09-27 |
DE3865982D1 (en) | 1991-12-12 |
EP0279675A1 (en) | 1988-08-24 |
KR890013295A (en) | 1989-09-22 |
JPS63132001U (en) | 1988-08-30 |
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