CA2661119A1 - Muff joint for concrete reinforcing rods - Google Patents
Muff joint for concrete reinforcing rods Download PDFInfo
- Publication number
- CA2661119A1 CA2661119A1 CA 2661119 CA2661119A CA2661119A1 CA 2661119 A1 CA2661119 A1 CA 2661119A1 CA 2661119 CA2661119 CA 2661119 CA 2661119 A CA2661119 A CA 2661119A CA 2661119 A1 CA2661119 A1 CA 2661119A1
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- CA
- Canada
- Prior art keywords
- muff
- concrete reinforcing
- recess
- reinforcing rod
- joint
- 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.)
- Abandoned
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/16—Auxiliary parts for reinforcements, e.g. connectors, spacers, stirrups
- E04C5/162—Connectors or means for connecting parts for reinforcements
- E04C5/163—Connectors or means for connecting parts for reinforcements the reinforcements running in one single direction
- E04C5/165—Coaxial connection by means of sleeves
Abstract
A muff joint for concrete reinforcing rods comprised of materials having different moduli of elasticity, particularly for a steel concrete reinforcing rod and a rod comprised of fiberglass reinforced plastic, wherewith one connecting end of each such concrete reinforcing rod is connected to a muff part which has at least one first recess for accommodating a first concrete reinforcing rod having a relative low modulus of elasticity, and said muff part has another connecting configuration, e.g. in particular a second recess, for a second concrete reinforcing rod having a relatively high modulus of elasticity; the inventive joint being distinguished in that at least one additional interior structure is provided in the first recess, which interior structure engages or otherwise cooperates in a mutual interaction of surfaces with complementary structures on the connecting end of the first concrete reinforcing rod which connecting end comes to be inserted in the muff part.
Description
Muff joint for concrete reinforcing rods Specification:
The present invention relates to a muff joint for concrete reinforcing rods comprised of materials having different moduli of elasticity, particularly for a steel concrete reinforcing rod and a rod comprised of fiberglass reinforced plastic, wherewith one connecting end of each such concrete reinforcing rod is connected to a muff part which has at least one first recess for accommodating a first concrete reinforcing rod having a relative low modulus of elasticity, and said muff part has another connecting configuration, e.g. in particular a second recess, for a second concrete reinforcing rod having a relatively high modulus of elasticity.
Such muff joints and muff parts for providing such connections are known. The muff part may be a two-part structure having a male section and a female section, as disclosed in, e.g., EP 1277892 Al or DE 201 10 720.
As a rule, the concrete reinforcing rods which are to be joined, and the muff part(s), are all comprised of steel material, and have generally the same parameters, particularly the same modulus of elasticity, so that when under load there is no tendency to suffer slippage between the connected components, which slippage is a hazard when a difference in moduli of elasticity is presented.
The Applicant has had occasion to use rods of other materials than steel (particularly stainless steel) as concrete reinforcing rods, in particular rods comprised of fiberglass reinforced plastic (FRP);
The present invention relates to a muff joint for concrete reinforcing rods comprised of materials having different moduli of elasticity, particularly for a steel concrete reinforcing rod and a rod comprised of fiberglass reinforced plastic, wherewith one connecting end of each such concrete reinforcing rod is connected to a muff part which has at least one first recess for accommodating a first concrete reinforcing rod having a relative low modulus of elasticity, and said muff part has another connecting configuration, e.g. in particular a second recess, for a second concrete reinforcing rod having a relatively high modulus of elasticity.
Such muff joints and muff parts for providing such connections are known. The muff part may be a two-part structure having a male section and a female section, as disclosed in, e.g., EP 1277892 Al or DE 201 10 720.
As a rule, the concrete reinforcing rods which are to be joined, and the muff part(s), are all comprised of steel material, and have generally the same parameters, particularly the same modulus of elasticity, so that when under load there is no tendency to suffer slippage between the connected components, which slippage is a hazard when a difference in moduli of elasticity is presented.
The Applicant has had occasion to use rods of other materials than steel (particularly stainless steel) as concrete reinforcing rods, in particular rods comprised of fiberglass reinforced plastic (FRP);
FRP rods have lower thermalconductivity than steel rods, and are less expensive. Also, they are easy to drill through and are more easily machinable -- both of which characteristics are advantageous in, e.g., tunnel construction.
When one seeks to join FRP rods and steel reinforcing rods, a problem arises in that the modulus of elasticity of the FRP rods is much lower than that of the steel rods, by a factor which in practice may be, e.g., 3.5. As mentioned, such a difference in moduli of elasticity can result in slipping at the joint locations, with the consequence that the joints do not have optimal resistance to loads. To determine the slipping, the quotient of the stress divided by the modulus of elasticity is integrated over the path;
accordingly, lengthening the overlap length in the region of joining of the FRP and steel components, by means of a correspondingly constructed muff joint, does not solve the problem, but is in fact counterproductive.
In light of the preceding, the underlying problem of the present invention was to devise an improved muff joint of the general type described supra, such that the muff joint can provide a reliable and firm joint between concrete reinforcing rods which are comprised of materials having appreciably different moduli of elasticity.
This problem is solved according to the invention by a muff joint having the features set forth in Patent Claim 1.
Advantageous refinements of the invention are set forth in the dependent claims, the wording of which is expressly incorporated in this Specification by reference (for the sake of avoiding redundancy).
According to the invention, a muff joint is provided which is usable for concrete reinforcing rods comprised of materials having different moduli of elasticity, particularly for a steel concrete reinforcing rod and a rod comprised of fiberglass reinforced plastic, wherewith one connecting end of each such concrete reinforcing rod is connected to a muff part which has at least one first recess for accommodating a first concrete reinforcing rod having a relative low modulus of elasticity, and said muff part has another connecting configuration, e.g. in particular a second recess, for a second concrete reinforcing rod having a relatively high modulus of elasticity; characterized in that at least one additional interior structure is provided in the first recess, which interior structure engages or otherwise cooperates in a mutual interaction of surfaces with complementary structures on the connecting end of the first concrete reinforcing rod which connecting end comes to be inserted in the muff part.
According to a basic concept of the invention, the configuration of the interior structure of the muff part and the complementary structures on the connecting end of the first concrete reinforcing rod provide an increased surface for contacting and activation [sic], between the given concrete reinforcing rod and the muff part, resulting in improved behavior under loads, which may enable a substantial reduction of the overlap length between the muff part and the inserted concrete reinforcing rod (compared to customary structures). The abovementioned additional activation [sic], combined with the reduced overlap length, contributes to reduced slipping, resulting in a more reliable and firm (robust) joint between the muff part and the said concrete reinforcing rod;
the muff joint is completed by connecting a second concrete reinforcing rod to the other end of the muff part.
The second recess provided for accommodating the second concrete reinforcing rod is not absolutely mandatory according to the invention. E.g. the connecting end of the second concrete reinforcing rod may be merely adhesively bonded in the aforesaid first recess.
In a refinement of the invention, the interior structure may be in the form of a geometrical body (such as a frustum of a cone, a hollow cylinder, or a group of lamellae or pins or the like) which project(s) into the first recess. The complementary structures on the connecting end of the first concrete reinforcing rod are preferably formed in said rod when it is in its curing state of its FRP
material.
According to a preferred refinement of the invention, the muff part has a reduced material thickness in its region of the first recess, compared to the rest of the muff part, in particular a reduced outer diameter. This feature contributes to avoidance of slipping [sic].
According to another refinement of the invention, the muff part has a generally frustoconical taper with progression toward its end, in the region of the first recess, the purpose of this taper being to reduce the material thickness of the muff part. The taper need not be a uniform straight-line taper; the outer periphery of the muff part in the tapering region may be curved, in particular concavely curved.
Preferably, the interior structure is symmetric with respect to (and/or is disposed symmetrically with respect to) the longitudinal axis of the muff part (or of the overall muff joint). In particular, this symmetry may be rotational symmetry.
According to yet another refinement of the invention, the inner wall of the first recess has a configuration which is complementary [sic] to the configuration of a corresponding wall of the interior structure. The configurations which are candidates for this may in particular be configurations in which the inner wall of the first recess and the corresponding wall of the interior structure are both parallel to the longitudinal axis of the muff part (or of the overall muff joint). It is also possible for the said two walls to be inclined with respect to the longitudinal axis of the device.
In order to increase the reliability and robustness of the joint, according to a highly preferred refinement of the invention at least one thread means is provided on the connecting end of the first concrete reinforcing rod; and at least one corresponding thread means is provided in the first recess of the muff part and/or in/on the interior structure.
Advantageously, the recess has a first interior thread and the interior structure has a first exterior thread. Complementarily to this, the connecting end of the concrete reinforcing rod has a first exterior thread which cooperates with the first interior thread of the muff part, and has a second interior thread which cooperates with the exterior thread of the interior structure of the muff part.
In particular in a situation where an adhesive material, such as a plastic resin or the like, is employed in the formation of the muff joint connection, it is advantageous if the aforesaid thread means and corresponding cooperating thread means respectively have different pitches and/or are shifted (e.g. offset) to some extent with respect to each other (so as to form a gap), with the aim of better distributing the adhesive material.
According to still another preferred refinement of the invention, in order to avoid slipping problems on the opposite end of the muff part, the muff part is comprised of a material which essentially corresponds to that of the second concrete reinforcing rod.
Additional features and advantages of the invention will be apparent from the following description of exemplary embodiments with reference to the accompanying drawings.
Fig. 1 is a specific embodiment of the inventive muff joint in a separated state;
Fig. 2 is a cross section along line B-B in Fig. 1;
Fig. 3 is a cross section along line C-C in Fig. 1;
Fig. 4 is a representation of the inventive muff joint according to Fig. 1 in the assembled state;
Fig. 5 is a cross section along line A-A in Fig. 4;
Fig. 6 is an alternative embodiment of the inventive muff joint in a separated state;
Fig. 7 is a cross section along line B-B in Fig. 6;
Fig. 8 is a cross section along line C-C in Fig. 6;
Fig. 9 illustrates the muff joint according to Fig. 6 in the assembled state;
Fig. 10 is a cross section along line A-A in Fig. 9;
Fig. 11 is yet a third embodiment of the inventive muff joint in a separated state;
Fig. 12 is a cross section along line B-B in Fig. 11;
Fig. 13 is a cross section along line C-C in Fig. 11;
Fig. 14 illustrates the muff joint according to Fig. 11 in the assembled state; and Fig. 15 is a cross section through line A-A in Fig. 14.
Fig. 1 shows an embodiment of the inventive muff joint for concrete reinforcing rods of materials having mutually different moduli of elasticity; the joint as a whole is designated with reference numeral 1. The joint 1 is shown in Fig. 1 in a separated state, with the concrete reinforcing rods (of which only one, the rod 2, is shown in Fig. 1) not having been inserted in the muff part 3. The muff joint 1 is particularly suited for joining a steel concrete reinforcing rod with a rod 2 comprised of a fiberglass reinforced plastic (FRP), where the materials have sharply differing moduli of elasticity.
For the stated purpose, the muff part 3 has a first recess 4 and a second (optional) recess 5, the two recesses being formed in opposite ends of the muff part 3. The first recess 4 serves to accommodate the illustrated concrete reinforcing rod 2 which has a relatively low modulus of elasticity. The second recess 5 serves to accommodate a second concrete reinforcing rod (not shown) which has an appreciably higher modulus of elasticity than rod 2.
The muff part 3 is preferably comprised of a material which has properties relating to its modulus of elasticity which properties are comparable to those of the material of the (not shown) second concrete reinforcing rod, wherewith preferably the material of the muff part 3 is a suitable steel. In particular in this connection it may be provided that the muff part 3 and the second concrete reinforcing rod may be joined (as an alternative) by simple adhesive bonding means, obviating the need for the second recess.
In order to avoid slippage [sic] in the region of connection of the first concrete reinforcing rod 2 and the muff part 3 as a result of the described difference in moduli of elasticity, the muff part 3 has a reduced material thickness (compared to the rest of muff part 3) in the region of the first recess 4. For this purpose, the outer diameter of the muff part in the said region is progressively reduced, e.g. in a tapering, with progression toward the corresponding end of the muff part 3.
Further means of avoiding slippage are provided in that the overlapping length UL of the first concrete reinforcing rod 2 and the muff part 3 can be reduced, in that means are provided whereby, in the illustrated embodiment of the muff joint 1, an additional interior structure 6 is provided in the first recess 4 which interior structure primarily comprises a frustoconical member (as seen particularly clearly in the cross sectional view in Fig. 3) which projects into the first recess 4. On the end of the first concrete reinforcing rod 2 which end is destined to be inserted into the recess 4, a complementary structure 7 corresponding to the interior structure 6 is provided, which structure 7 comprises a frustoconical recess, wherewith the structures 6 and 7 closely interengage when the concrete reinforcing rod is inserted in the muff part 3. The "close interengagement" is such that an enlarged abutting surface (contact surface) is provided via the interior structure 6 and complementary structure 7, between the concrete reinforcing rod 2 and the muff part 3, whereby despite the relatively short overlapping length UL an improved material activation [sic] for stress transmission is provided, which contributes to reduction of slippage.
Additional engineering design features of the embodiment according to Fig. 1 will now be discussed, with reference to Figs. 2 and 3.
The interior strucuure 6 of the muff part 3 and the complementary structure 7 of the concrete reinforcing rod 2 are of configurations which are symmetric with respect to (and/or are disposed symmetrically with respect to) the longitudinal axis L of the muff joint 1, as shown.
The concrete reinforcing rod 2, which preferably is comprised of FRP, has a conically tapering connecting end, and the first recess 4 of the muff part 3 has a complementary shape. In the ideal case, this special configuration will result in linear loading behavior in the contact and connection region.
The concrete reinforcing rod 2 also has on its connecting end an outer thread 8, and the muff part 3 has a corresponding inner thread 9 in the region of its first recess 4. Also in the region of the complementary structure 7 the concrete reinforcing rod 2 has a second inner thread 10 (see Fig. 2), and the interior structure 6 of the muff part 3 has a complementary outer thread 11 (see Fig. 3).
The threading of the concrete reinforcing rod 2 on the one hand and of the muff part 3 on the other hand can be mutually shifted and/or can have different pitches, with the aim of ensuring a firm interconnection of the two components, particularly when an adhesive agent is applied (e.g. a plastic resin) in the region of the first recess in order to contribute to a secure connection.
Because of the alternating inner and outer surfaces with progression in the transverse direction (surfaces of the interior structure 6 and exterior structure 7), a mutual "resistance" to transverse contraction is provided by the concrete reinforcing rod 2 and muff part 3 in the face of the tensile and compressive stresses which will occur. Particular effective resistance to transverse contraction is provided by straight surfaces presented in the outward direction by the first concrete reinforcing rod 2 and in the inward direction by the muff part 3 (for a good example of which see the particular embodiment illustrated in Fig. 5).
In the region of the second recess 5, which serves to accommodate the (not shown) second concrete reinforcing rod, a thread 12 is provided which may be configured to connected to the said second rod in a manner which is per se known.
Figs. 4 and 5 show the embodiment of the inventive muff joint according to Figs. 1-3 in an assembled state, wherewith the reference numeral 2' designates the second concrete reinforcing rod;
no further description of Figs. 4 and 5 is needed beyond that provided above.
Figs. 6-10 illustrate a second embodiment of the inventive muff joint 1. For reasons of brevity, only the important differences between that embodiment and the embodiment according to Figs. 1-5 will now be described.
The muff part 3 and concrete reinforcing rod 2 illustrated in Figs. 6-10 [lit., "4-6"] have yet a shorter overlap region UL. Also the reduction in radius a and in cross section, of the muff part, according to Fig. 6, is more pronounced than in Figs. 1-5.
To accommodate these features, the interior structure 6 in the region of the first recess 4 of the muff part 3 also has a frustoconical cross section (see Fig. 8), but it further has a central frustoconical recess 13, which is oriented oppositely to the frustoconical shape of the remainder of the interior structure 6.
The structure 7 on the connecting end of the concrete reinforcing rod 2 is once again complementary to the interior structure 6 (as described), being comprised of a conical recess (similar to that of Figs. 1-5) but which has invading its center region an oppositely oriented frustoconical projection 14 which is configured so as to suitably engage the added recess 13 in the muff part 3.
Unlike the concrete reinforcing rod 2 of Figs. 1-5, the rod 2 of this embodiment does not narrow on its connecting end; and correspondingly the outer wall 15 of the recess 4 of the muff part 3 is parallel to the longitudinal axis L of the muff joint 1.
This configuration also provides a large surface of engagement between the concrete reinforcing rod 2 and the muff part 3 in the region of the joint, contributing to improved material activation [sic], thereby allowing a smaller overlap region UL while reducing slipping.
In Figs. 9 and 10 the described second exemplary embodiment of the muff joint 1 is illustrated in the assembled state.
As with the embodiment according to Figs. 1-5, suitable thread means may be provided at the connecting end of the concrete reinforcing rod 2 and complementary thread means may be provided in the region of the first recess 4 of the muff part 3; for the sake of simplicity in the drawings, these threads are not shown in detail.
Figs. 11-15 illustrate a third exemplary embodiment of the inventive muff joint 1; once again, in the description that follows, only appreciable differences between this third embodiment and the embodiments already described will be discussed.
The embodiment illustrated in Figs. 11-15 resembles that of Figs. 6-10, with the principal difference being that in this third embodiment the projecting structures in the region of the first recess 4 of the muff part 3, which structures form the so-called "interior structure" 6, have walls (16, 17) which are parallel to the longitudinal axis L of the muff joint 1. The overall general configuration of the interior structure 6 is that of a hollow cylinder; and the structure on the connecting end of the concrete reinforcing rod 2 has a complementary shape, as seen in the Figures.
In the region of the recess 4 and the connecting end of the concrete reinforcing rod 2, thread means may be provided (analogously to the examples described above); these are not shown explicitly in Figs. 11-15.
It should be noted that the present invention is not limited to the above-described exemplary embodiments, all of which, e.g., are rotationally symmetric. For example, the interior structure 6 may be in the form of a (preferably uniform) parallel array of lamellae (1-dimensional array) or pins (2-dimensional array) or the like, which engages complementary structures (recesses) at the connecting end of the concrete reinforcing rod 2, in order to provide the maximum possible contact surface.
When one seeks to join FRP rods and steel reinforcing rods, a problem arises in that the modulus of elasticity of the FRP rods is much lower than that of the steel rods, by a factor which in practice may be, e.g., 3.5. As mentioned, such a difference in moduli of elasticity can result in slipping at the joint locations, with the consequence that the joints do not have optimal resistance to loads. To determine the slipping, the quotient of the stress divided by the modulus of elasticity is integrated over the path;
accordingly, lengthening the overlap length in the region of joining of the FRP and steel components, by means of a correspondingly constructed muff joint, does not solve the problem, but is in fact counterproductive.
In light of the preceding, the underlying problem of the present invention was to devise an improved muff joint of the general type described supra, such that the muff joint can provide a reliable and firm joint between concrete reinforcing rods which are comprised of materials having appreciably different moduli of elasticity.
This problem is solved according to the invention by a muff joint having the features set forth in Patent Claim 1.
Advantageous refinements of the invention are set forth in the dependent claims, the wording of which is expressly incorporated in this Specification by reference (for the sake of avoiding redundancy).
According to the invention, a muff joint is provided which is usable for concrete reinforcing rods comprised of materials having different moduli of elasticity, particularly for a steel concrete reinforcing rod and a rod comprised of fiberglass reinforced plastic, wherewith one connecting end of each such concrete reinforcing rod is connected to a muff part which has at least one first recess for accommodating a first concrete reinforcing rod having a relative low modulus of elasticity, and said muff part has another connecting configuration, e.g. in particular a second recess, for a second concrete reinforcing rod having a relatively high modulus of elasticity; characterized in that at least one additional interior structure is provided in the first recess, which interior structure engages or otherwise cooperates in a mutual interaction of surfaces with complementary structures on the connecting end of the first concrete reinforcing rod which connecting end comes to be inserted in the muff part.
According to a basic concept of the invention, the configuration of the interior structure of the muff part and the complementary structures on the connecting end of the first concrete reinforcing rod provide an increased surface for contacting and activation [sic], between the given concrete reinforcing rod and the muff part, resulting in improved behavior under loads, which may enable a substantial reduction of the overlap length between the muff part and the inserted concrete reinforcing rod (compared to customary structures). The abovementioned additional activation [sic], combined with the reduced overlap length, contributes to reduced slipping, resulting in a more reliable and firm (robust) joint between the muff part and the said concrete reinforcing rod;
the muff joint is completed by connecting a second concrete reinforcing rod to the other end of the muff part.
The second recess provided for accommodating the second concrete reinforcing rod is not absolutely mandatory according to the invention. E.g. the connecting end of the second concrete reinforcing rod may be merely adhesively bonded in the aforesaid first recess.
In a refinement of the invention, the interior structure may be in the form of a geometrical body (such as a frustum of a cone, a hollow cylinder, or a group of lamellae or pins or the like) which project(s) into the first recess. The complementary structures on the connecting end of the first concrete reinforcing rod are preferably formed in said rod when it is in its curing state of its FRP
material.
According to a preferred refinement of the invention, the muff part has a reduced material thickness in its region of the first recess, compared to the rest of the muff part, in particular a reduced outer diameter. This feature contributes to avoidance of slipping [sic].
According to another refinement of the invention, the muff part has a generally frustoconical taper with progression toward its end, in the region of the first recess, the purpose of this taper being to reduce the material thickness of the muff part. The taper need not be a uniform straight-line taper; the outer periphery of the muff part in the tapering region may be curved, in particular concavely curved.
Preferably, the interior structure is symmetric with respect to (and/or is disposed symmetrically with respect to) the longitudinal axis of the muff part (or of the overall muff joint). In particular, this symmetry may be rotational symmetry.
According to yet another refinement of the invention, the inner wall of the first recess has a configuration which is complementary [sic] to the configuration of a corresponding wall of the interior structure. The configurations which are candidates for this may in particular be configurations in which the inner wall of the first recess and the corresponding wall of the interior structure are both parallel to the longitudinal axis of the muff part (or of the overall muff joint). It is also possible for the said two walls to be inclined with respect to the longitudinal axis of the device.
In order to increase the reliability and robustness of the joint, according to a highly preferred refinement of the invention at least one thread means is provided on the connecting end of the first concrete reinforcing rod; and at least one corresponding thread means is provided in the first recess of the muff part and/or in/on the interior structure.
Advantageously, the recess has a first interior thread and the interior structure has a first exterior thread. Complementarily to this, the connecting end of the concrete reinforcing rod has a first exterior thread which cooperates with the first interior thread of the muff part, and has a second interior thread which cooperates with the exterior thread of the interior structure of the muff part.
In particular in a situation where an adhesive material, such as a plastic resin or the like, is employed in the formation of the muff joint connection, it is advantageous if the aforesaid thread means and corresponding cooperating thread means respectively have different pitches and/or are shifted (e.g. offset) to some extent with respect to each other (so as to form a gap), with the aim of better distributing the adhesive material.
According to still another preferred refinement of the invention, in order to avoid slipping problems on the opposite end of the muff part, the muff part is comprised of a material which essentially corresponds to that of the second concrete reinforcing rod.
Additional features and advantages of the invention will be apparent from the following description of exemplary embodiments with reference to the accompanying drawings.
Fig. 1 is a specific embodiment of the inventive muff joint in a separated state;
Fig. 2 is a cross section along line B-B in Fig. 1;
Fig. 3 is a cross section along line C-C in Fig. 1;
Fig. 4 is a representation of the inventive muff joint according to Fig. 1 in the assembled state;
Fig. 5 is a cross section along line A-A in Fig. 4;
Fig. 6 is an alternative embodiment of the inventive muff joint in a separated state;
Fig. 7 is a cross section along line B-B in Fig. 6;
Fig. 8 is a cross section along line C-C in Fig. 6;
Fig. 9 illustrates the muff joint according to Fig. 6 in the assembled state;
Fig. 10 is a cross section along line A-A in Fig. 9;
Fig. 11 is yet a third embodiment of the inventive muff joint in a separated state;
Fig. 12 is a cross section along line B-B in Fig. 11;
Fig. 13 is a cross section along line C-C in Fig. 11;
Fig. 14 illustrates the muff joint according to Fig. 11 in the assembled state; and Fig. 15 is a cross section through line A-A in Fig. 14.
Fig. 1 shows an embodiment of the inventive muff joint for concrete reinforcing rods of materials having mutually different moduli of elasticity; the joint as a whole is designated with reference numeral 1. The joint 1 is shown in Fig. 1 in a separated state, with the concrete reinforcing rods (of which only one, the rod 2, is shown in Fig. 1) not having been inserted in the muff part 3. The muff joint 1 is particularly suited for joining a steel concrete reinforcing rod with a rod 2 comprised of a fiberglass reinforced plastic (FRP), where the materials have sharply differing moduli of elasticity.
For the stated purpose, the muff part 3 has a first recess 4 and a second (optional) recess 5, the two recesses being formed in opposite ends of the muff part 3. The first recess 4 serves to accommodate the illustrated concrete reinforcing rod 2 which has a relatively low modulus of elasticity. The second recess 5 serves to accommodate a second concrete reinforcing rod (not shown) which has an appreciably higher modulus of elasticity than rod 2.
The muff part 3 is preferably comprised of a material which has properties relating to its modulus of elasticity which properties are comparable to those of the material of the (not shown) second concrete reinforcing rod, wherewith preferably the material of the muff part 3 is a suitable steel. In particular in this connection it may be provided that the muff part 3 and the second concrete reinforcing rod may be joined (as an alternative) by simple adhesive bonding means, obviating the need for the second recess.
In order to avoid slippage [sic] in the region of connection of the first concrete reinforcing rod 2 and the muff part 3 as a result of the described difference in moduli of elasticity, the muff part 3 has a reduced material thickness (compared to the rest of muff part 3) in the region of the first recess 4. For this purpose, the outer diameter of the muff part in the said region is progressively reduced, e.g. in a tapering, with progression toward the corresponding end of the muff part 3.
Further means of avoiding slippage are provided in that the overlapping length UL of the first concrete reinforcing rod 2 and the muff part 3 can be reduced, in that means are provided whereby, in the illustrated embodiment of the muff joint 1, an additional interior structure 6 is provided in the first recess 4 which interior structure primarily comprises a frustoconical member (as seen particularly clearly in the cross sectional view in Fig. 3) which projects into the first recess 4. On the end of the first concrete reinforcing rod 2 which end is destined to be inserted into the recess 4, a complementary structure 7 corresponding to the interior structure 6 is provided, which structure 7 comprises a frustoconical recess, wherewith the structures 6 and 7 closely interengage when the concrete reinforcing rod is inserted in the muff part 3. The "close interengagement" is such that an enlarged abutting surface (contact surface) is provided via the interior structure 6 and complementary structure 7, between the concrete reinforcing rod 2 and the muff part 3, whereby despite the relatively short overlapping length UL an improved material activation [sic] for stress transmission is provided, which contributes to reduction of slippage.
Additional engineering design features of the embodiment according to Fig. 1 will now be discussed, with reference to Figs. 2 and 3.
The interior strucuure 6 of the muff part 3 and the complementary structure 7 of the concrete reinforcing rod 2 are of configurations which are symmetric with respect to (and/or are disposed symmetrically with respect to) the longitudinal axis L of the muff joint 1, as shown.
The concrete reinforcing rod 2, which preferably is comprised of FRP, has a conically tapering connecting end, and the first recess 4 of the muff part 3 has a complementary shape. In the ideal case, this special configuration will result in linear loading behavior in the contact and connection region.
The concrete reinforcing rod 2 also has on its connecting end an outer thread 8, and the muff part 3 has a corresponding inner thread 9 in the region of its first recess 4. Also in the region of the complementary structure 7 the concrete reinforcing rod 2 has a second inner thread 10 (see Fig. 2), and the interior structure 6 of the muff part 3 has a complementary outer thread 11 (see Fig. 3).
The threading of the concrete reinforcing rod 2 on the one hand and of the muff part 3 on the other hand can be mutually shifted and/or can have different pitches, with the aim of ensuring a firm interconnection of the two components, particularly when an adhesive agent is applied (e.g. a plastic resin) in the region of the first recess in order to contribute to a secure connection.
Because of the alternating inner and outer surfaces with progression in the transverse direction (surfaces of the interior structure 6 and exterior structure 7), a mutual "resistance" to transverse contraction is provided by the concrete reinforcing rod 2 and muff part 3 in the face of the tensile and compressive stresses which will occur. Particular effective resistance to transverse contraction is provided by straight surfaces presented in the outward direction by the first concrete reinforcing rod 2 and in the inward direction by the muff part 3 (for a good example of which see the particular embodiment illustrated in Fig. 5).
In the region of the second recess 5, which serves to accommodate the (not shown) second concrete reinforcing rod, a thread 12 is provided which may be configured to connected to the said second rod in a manner which is per se known.
Figs. 4 and 5 show the embodiment of the inventive muff joint according to Figs. 1-3 in an assembled state, wherewith the reference numeral 2' designates the second concrete reinforcing rod;
no further description of Figs. 4 and 5 is needed beyond that provided above.
Figs. 6-10 illustrate a second embodiment of the inventive muff joint 1. For reasons of brevity, only the important differences between that embodiment and the embodiment according to Figs. 1-5 will now be described.
The muff part 3 and concrete reinforcing rod 2 illustrated in Figs. 6-10 [lit., "4-6"] have yet a shorter overlap region UL. Also the reduction in radius a and in cross section, of the muff part, according to Fig. 6, is more pronounced than in Figs. 1-5.
To accommodate these features, the interior structure 6 in the region of the first recess 4 of the muff part 3 also has a frustoconical cross section (see Fig. 8), but it further has a central frustoconical recess 13, which is oriented oppositely to the frustoconical shape of the remainder of the interior structure 6.
The structure 7 on the connecting end of the concrete reinforcing rod 2 is once again complementary to the interior structure 6 (as described), being comprised of a conical recess (similar to that of Figs. 1-5) but which has invading its center region an oppositely oriented frustoconical projection 14 which is configured so as to suitably engage the added recess 13 in the muff part 3.
Unlike the concrete reinforcing rod 2 of Figs. 1-5, the rod 2 of this embodiment does not narrow on its connecting end; and correspondingly the outer wall 15 of the recess 4 of the muff part 3 is parallel to the longitudinal axis L of the muff joint 1.
This configuration also provides a large surface of engagement between the concrete reinforcing rod 2 and the muff part 3 in the region of the joint, contributing to improved material activation [sic], thereby allowing a smaller overlap region UL while reducing slipping.
In Figs. 9 and 10 the described second exemplary embodiment of the muff joint 1 is illustrated in the assembled state.
As with the embodiment according to Figs. 1-5, suitable thread means may be provided at the connecting end of the concrete reinforcing rod 2 and complementary thread means may be provided in the region of the first recess 4 of the muff part 3; for the sake of simplicity in the drawings, these threads are not shown in detail.
Figs. 11-15 illustrate a third exemplary embodiment of the inventive muff joint 1; once again, in the description that follows, only appreciable differences between this third embodiment and the embodiments already described will be discussed.
The embodiment illustrated in Figs. 11-15 resembles that of Figs. 6-10, with the principal difference being that in this third embodiment the projecting structures in the region of the first recess 4 of the muff part 3, which structures form the so-called "interior structure" 6, have walls (16, 17) which are parallel to the longitudinal axis L of the muff joint 1. The overall general configuration of the interior structure 6 is that of a hollow cylinder; and the structure on the connecting end of the concrete reinforcing rod 2 has a complementary shape, as seen in the Figures.
In the region of the recess 4 and the connecting end of the concrete reinforcing rod 2, thread means may be provided (analogously to the examples described above); these are not shown explicitly in Figs. 11-15.
It should be noted that the present invention is not limited to the above-described exemplary embodiments, all of which, e.g., are rotationally symmetric. For example, the interior structure 6 may be in the form of a (preferably uniform) parallel array of lamellae (1-dimensional array) or pins (2-dimensional array) or the like, which engages complementary structures (recesses) at the connecting end of the concrete reinforcing rod 2, in order to provide the maximum possible contact surface.
Claims (14)
1. A muff joint (1) for concrete reinforcing rods (2) comprised of materials having different moduli of elasticity, particularly for a steel concrete reinforcing rod (2') and a rod (2) comprised of fiberglass reinforced plastic, wherewith one connecting end of the concrete reinforcing rod (2) is connected to a muff part (3) which has at least one first recess (4) for accommodating a first concrete reinforcing rod (2) having a relative low modulus of elasticity, and said muff part (3) has another connecting configuration, e.g. in particular a second recess (5), for a second concrete reinforcing rod (2') having a relatively high modulus of elasticity;
characterized in that at least one additional interior structure (6) is provided in the first recess (4), which structure (6) engages or otherwise cooperates in a mutual interaction of surfaces with complementary structures (7) on the connecting end of the first concrete reinforcing rod (2) which connecting end comes to be inserted in the muff part (3).
characterized in that at least one additional interior structure (6) is provided in the first recess (4), which structure (6) engages or otherwise cooperates in a mutual interaction of surfaces with complementary structures (7) on the connecting end of the first concrete reinforcing rod (2) which connecting end comes to be inserted in the muff part (3).
2. A muff joint (1) according to claim 1; characterized in that the muff part (3) has a reduced material thickness in its region of the first recess (4), compared to the rest of the muff part (3), in particular a reduced outer diameter.
3. A muff joint (1) according to claim 1 or 2; characterized in that the muff part (3) has a generally frustoconical taper (a) with progression toward its end, in the region of the first recess (4).
4. A muff joint (1) according to at least one of claims 1-3;
characterized in that the interior structure (6) is symmetric with respect to (and/or is disposed symmetrically with respect to) the longitudinal axis (L) of the muff part (3).
characterized in that the interior structure (6) is symmetric with respect to (and/or is disposed symmetrically with respect to) the longitudinal axis (L) of the muff part (3).
5. A muff joint (1) according to at least one of claims 1-4;
characterized in that the interior structure (6) is rotationally symmetric with respect to the longitudinal axis (L) of the muff part (3).
characterized in that the interior structure (6) is rotationally symmetric with respect to the longitudinal axis (L) of the muff part (3).
6. A muff joint (1) according to at least one of claims 1-5;
characterized in that the interior structure (6) is in the form of a frustoconical structure which projects into the first recess (4).
characterized in that the interior structure (6) is in the form of a frustoconical structure which projects into the first recess (4).
7. A muff joint (1) according to at least one of claims 1-5;
characterized in that the interior structure (6) is in the form of a hollow cylinder which projects into the first recess (4).
characterized in that the interior structure (6) is in the form of a hollow cylinder which projects into the first recess (4).
8. A muff joint (1) according to at least one of claims 1-5;
characterized in that the interior structure (6) is in the form of a number of lamellae, pins, or the like.
characterized in that the interior structure (6) is in the form of a number of lamellae, pins, or the like.
9. A muff joint (1) according to at least one of claims 1-8;
characterized in that the inner wall (15) of the first recess (4) has a configuration which is complementary [sic] to the configuration of a corresponding wall (17) of the interior structure (6).
characterized in that the inner wall (15) of the first recess (4) has a configuration which is complementary [sic] to the configuration of a corresponding wall (17) of the interior structure (6).
10. A muff joint (1) according to at least one of claims 1-9;
characterized in that at least one thread means (8, 10) is provided on the connecting end of the first concrete reinforcing rod (2);
and in that at least one corresponding thread means (9, 11) is provided in the first recess (4) of the muff part (3) and/or in/on the interior structure (6).
characterized in that at least one thread means (8, 10) is provided on the connecting end of the first concrete reinforcing rod (2);
and in that at least one corresponding thread means (9, 11) is provided in the first recess (4) of the muff part (3) and/or in/on the interior structure (6).
11. A muff joint (1) according to at least claim 10 [sic];
characterized in that the thread means (8, 10) and the corresponding thread means (9, 11) respectively have different pitches and/or are shifted (e.g. offset) to some extent with respect to each other.
characterized in that the thread means (8, 10) and the corresponding thread means (9, 11) respectively have different pitches and/or are shifted (e.g. offset) to some extent with respect to each other.
12. A muff joint (1) according to at least one of claims 1-11;
characterized in that the muff part (3) has an essentially uniform cylindrical shape with constant outer cross section, in the region of the second recess (5).
characterized in that the muff part (3) has an essentially uniform cylindrical shape with constant outer cross section, in the region of the second recess (5).
13. A muff joint (1) according to at least one of claims 1-12;
characterized in that the muff part (3) is comprised of a material which essentially corresponds to that of the second concrete reinforcing rod (2'), e.g. in particular steel.
characterized in that the muff part (3) is comprised of a material which essentially corresponds to that of the second concrete reinforcing rod (2'), e.g. in particular steel.
14. A muff joint (1) according to at least one of claims 1-13;
characterized in that at least the first concrete reinforcing rod (2) is adhesively bonded in the muff part (3).
characterized in that at least the first concrete reinforcing rod (2) is adhesively bonded in the muff part (3).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE200810018325 DE102008018325A1 (en) | 2008-04-11 | 2008-04-11 | Socket joint for concrete reinforcement bars |
| DE102008018325.3 | 2008-04-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2661119A1 true CA2661119A1 (en) | 2009-10-11 |
Family
ID=40565009
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2661119 Abandoned CA2661119A1 (en) | 2008-04-11 | 2009-04-01 | Muff joint for concrete reinforcing rods |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP2108759B1 (en) |
| CA (1) | CA2661119A1 (en) |
| DE (1) | DE102008018325A1 (en) |
| DK (1) | DK2108759T3 (en) |
| PL (1) | PL2108759T3 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103671440A (en) * | 2013-11-22 | 2014-03-26 | 江苏天舜金属材料集团有限公司 | Midair multipoint vertical steel bar connecting joint and construction method thereof |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102016113558A1 (en) | 2016-07-22 | 2018-01-25 | Schöck Bauteile GmbH | Component for thermal insulation |
| DK3272957T3 (en) | 2016-07-22 | 2019-12-16 | Schoeck Bauteile Gmbh | BUILDING ELEMENT FOR HEAT INSULATION |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4027230C2 (en) * | 1990-08-29 | 1994-02-17 | Wayss & Freytag Ag | Screw socket connection |
| AUPO219296A0 (en) * | 1996-09-06 | 1996-10-03 | Alan H. Reid Pty Ltd | Threaded fastener having insertion depth indicator |
| GB2337477A (en) * | 1998-05-22 | 1999-11-24 | Epoxy Powder Coating Company L | Manufacturing a screw connection and apparatus therefore |
| DE20110720U1 (en) | 2001-06-29 | 2001-08-30 | Schoeck Entwicklungsgmbh | Socket connection for reinforcing bars |
| DE20111793U1 (en) | 2001-07-19 | 2001-09-20 | Schoeck Entwicklungsgmbh | Socket connection for concrete bars |
| WO2005035892A1 (en) * | 2003-10-10 | 2005-04-21 | Hitek Construction Ag | Device comprising a rod made of fiber-reinforced plastic for transferring a load through a heat-insulating layer |
-
2008
- 2008-04-11 DE DE200810018325 patent/DE102008018325A1/en not_active Withdrawn
-
2009
- 2009-02-07 PL PL09001737T patent/PL2108759T3/en unknown
- 2009-02-07 DK DK09001737.7T patent/DK2108759T3/en active
- 2009-02-07 EP EP09001737.7A patent/EP2108759B1/en not_active Not-in-force
- 2009-04-01 CA CA 2661119 patent/CA2661119A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103671440A (en) * | 2013-11-22 | 2014-03-26 | 江苏天舜金属材料集团有限公司 | Midair multipoint vertical steel bar connecting joint and construction method thereof |
| CN103671440B (en) * | 2013-11-22 | 2015-10-28 | 江苏天舜金属材料集团有限公司 | A kind of aerial vertical steel bar connecting joints of multiple spot and method of construction thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| DE102008018325A1 (en) | 2009-10-15 |
| DK2108759T3 (en) | 2016-09-26 |
| EP2108759B1 (en) | 2016-08-10 |
| EP2108759A3 (en) | 2012-05-09 |
| EP2108759A2 (en) | 2009-10-14 |
| PL2108759T3 (en) | 2017-02-28 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Dead |
Effective date: 20130402 |