GB2128704A - Rod coupler - Google Patents
Rod coupler Download PDFInfo
- Publication number
- GB2128704A GB2128704A GB08327112A GB8327112A GB2128704A GB 2128704 A GB2128704 A GB 2128704A GB 08327112 A GB08327112 A GB 08327112A GB 8327112 A GB8327112 A GB 8327112A GB 2128704 A GB2128704 A GB 2128704A
- Authority
- GB
- United Kingdom
- Prior art keywords
- coupler
- bars
- bar
- ofthe
- parent
- 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.)
- Granted
Links
- 230000008878 coupling Effects 0.000 claims abstract description 25
- 238000010168 coupling process Methods 0.000 claims abstract description 25
- 238000005859 coupling reaction Methods 0.000 claims abstract description 25
- 230000009467 reduction Effects 0.000 claims abstract description 8
- 239000011150 reinforced concrete Substances 0.000 claims abstract description 5
- 230000013011 mating Effects 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 11
- 238000011835 investigation Methods 0.000 claims description 9
- 238000012546 transfer Methods 0.000 claims description 8
- 239000004567 concrete Substances 0.000 claims description 6
- 238000007796 conventional method Methods 0.000 claims description 5
- 238000013461 design Methods 0.000 claims description 5
- 238000005520 cutting process Methods 0.000 claims description 4
- 238000009826 distribution Methods 0.000 claims description 4
- 230000002787 reinforcement Effects 0.000 claims description 4
- 238000010276 construction Methods 0.000 claims description 3
- 230000007704 transition Effects 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 2
- 238000007373 indentation Methods 0.000 claims description 2
- 230000000750 progressive effect Effects 0.000 claims description 2
- 239000010959 steel Substances 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 3
- 230000003014 reinforcing effect Effects 0.000 abstract description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B7/00—Connections of rods or tubes, e.g. of non-circular section, mutually, including resilient connections
- F16B7/18—Connections of rods or tubes, e.g. of non-circular section, mutually, including resilient connections using screw-thread elements
- F16B7/182—Connections of rods or tubes, e.g. of non-circular section, mutually, including resilient connections using screw-thread elements for coaxial connections of two rods or tubes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B4/00—Shrinkage connections, e.g. assembled with the parts at different temperature; Force fits; Non-releasable friction-grip fastenings
- F16B4/004—Press fits, force fits, interference fits, i.e. fits without heat or chemical treatment
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B7/00—Connections of rods or tubes, e.g. of non-circular section, mutually, including resilient connections
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Reinforcement Elements For Buildings (AREA)
Abstract
A technique of coupling bars 10 is characterized by progressively reducing the diameter of the bars in calculated steps and correspondingly increasing the wall thickness of the coupler 11. Conventional couplers have an outside diameter of about 1.5 times that of the bars. With this technique the outer diameter of the coupler can be reduced to about 1.3 times that of the bars. Reduction in the outer diameter will allow such couplers to be used extensively in reinforced concrete work for joining reinforcing bars. <IMAGE>
Description
SPECIFICATION
Atechnique or reducing diameterof couplersfor connecting bars
This invention relates to reinforcing and prestressing bars, structural ties and anchors of various kind in civil engineering works.
The standard type of mechanical couplers available for obtaining a full tension or compression joint in structural bars, are based on housing the ends of the parent bars into a hollow tubular element of suitable length and having an area of cross-section at least equal to the parent bars. The actual connection is accomplished by either using mating screwthreads on the bars andthe coupler or by mechanically squeezing the coupleron to the parent bars. Sincethe area of cross-section of the coupler is always on the outside ofthe parent bars, there is a significant increase in the diameter ofthe member at the location ofthecouplerwhichisa cause of great deal of inconvenience in construction works.The outside diameterofa coupler istypicallyi.Stimesthe diameter ofthe parnntbars.
The proposed technique permits significant reductions in the outer diameter of a coupling device and is based on progressively reducing the diameter ofthe parent bars in calculated steps and correspondingly increasing the wall thickness ofthecoupler inwards.
Theforce carrying capacity of the coupler at any section along its length should be at least equal to the force transferred from the parent bartothe coupler. If the coupler material is the same as the parent bars, then it would imply that the cross-sectional area ofthe coupler atthe critical sectionsshould be at least equal tothecross-sectionai;;area ofthe pa rent bar from which force is being transferred to the coupleratthat section. A desired factorof safety can be incorporated in the coupler design by/providing larger area of cross-section in the coupler than the parent bars at the critical sections. Theconnection between the bars and the couplerforforcetransfer can be established by any conventional method such as by mating screw threads or by squeezing an initially oversized coupler ontothe bars. Inthe latter system high gradual development of grip between the mating surfaces must be ensured. The length ofthe mating surfaces and the details oftransition between different diameters will be determined by strain distribution in the connection and by experimental investigations.
Accompanying drawings which have been referred to inthefoilowing examples are,
Fig. 1 half longitudinal section of a proposed coupling
Fig. 2Section AA
Fig. 3 Section BB
Fig. 4Section CC
In orderto illustrate the principles involved, assume thatthe parent bar marked 10in the drawings is of 40 mm diameter and the coupler marked 11 is of the same material as the parent bar. Assume also an increase in the internal diameter of the coupler by say 1 mm at each mating surface marked 13, 15 and 17, due to threads or otherfriction causing indentations, above the effective diameter of the bar atthe corresponding mating surfaces marked 12, and 16 respectively.The following sets of calculations under (a) and (b), (for notations see Figs. 1 to 4) will indicate how couplers of various outside diameters D can be designed for d=40mm parent barfor 100% efficiency ofthe joint.
(a) Assume that a coupler of D=48 mm outer diameter is required i.e. 1 .2timesthe diameter ofthe parent bar. The following are statements satisfying safe transfer of forces from the bar to the coupler at sections AA,BB and CC.
482-412=402-d12; .. d1 = 31.3 mm 482-32.32-d22; .. d2= 18.4 mm 482 -18.42=44.32 > 402 This proves that the force in the parent bar can be safely transferred to the coupler by reducing the diameter ofthe bar in two additional steps and correspondingly thickening the couplerwall. From the last calculation step it is obvious that a factor of safety is available in the coupler and it can be evenly distributed at each critical section.As can be seen from the following steps, a uniform factor of safety of over 1.09 is available if d1 and d2 are calculated as follows, 48241 2=(402-d12)x 1.09; .-. do=32.1 mm 482-33.12=(402-d22) XI .09;.. d2=22.2 m m 482-23.22=402x 1.09 (b) Assumethata coupler of D=52 mm outer diameter is acceptable i.e. 1.3 timesthe diameter of the parent bar. The following statements show that onlyone reduction in diameter will be required and a factor of safety of over 1.19 is available in the coupler.
522-412=(402-d12)x 1.19;:. do = 27.2 mm 522~ 28.22 = 43.72=402 x 1.19
If a differentfactor of safety say 1.25, is desired at the first critical section AA, then the following statements indicate that a factor of safety of 1.16 is available atthe second critical section BB, 522-412=(402-d12)x1.25; :. d1=28mm 522-292=402x 1.16
To join bars of different diameters, one could use a coupler which has stepped diameters as suggested hereforthe larger bar and a conventional single diameterforthe smaller bar.Alternatively since the strength required from such a connection is usually equal to smaller bar, the end part of the larger bar itself can act as half of a coupler and stepped diameters produced inside the end of larger bar and on the outside of the engaging smaller bar.
Due to structural reasons or for convenience, it may be permissible to allow loss of cross-sectional area of the parent bar atthe location of the coupler e.g. for cutting threads on the parent bar. For instance a 40 mm diameter bar may be allowed to lose up to 10% of its diameter resulting in a force carrying capacity at the connection of only 36 mm diameter section. The following calculations indicate that a coupler of 48 mm outer diameter and only one reduced diameter will give a safety factor of about 30% in the coupler.
482-372-(362-d12)x1.3; :. d1=24mm 482-252=362x1 3 If it is acceptable to use material of greater strength than the bars, for the manufacture ofthe coupler, then further reductions in the outer diameter of the coupler will result. If a material of say2.4timesthestrength of the parent bars is used for the manufacture ofthe coupler, then for a full strength connection between two 40 mm bars, a 45 mm coupler will be adequate with a single stepping down of diameter and will provide 40% spare strength available in the coupler as indicated by the following statements, 2.4x(452-412)=(402-d12)x1.4; .'. d=31.8mm 2.4x (452-32.82)=402x 1.4 Similar calculations can be performed for any size of bar.
Occasionally it is desirable to adopt a hexagonal or an octagonal outer cross-section of the coupler. In such cases the effective diameter D will correspond to a circle enclosing the same area as the actual outer cross-section ofthe coupler.
In all cases the final choice of diameters may have be rounded offto convenient sizes and adjusted in the light of experimental investigations.
Examples given above illustrate howthe concept of progressive step-wise reductions in bar and coupler inside diameter leads to significant reductions in the outer diameter of such couplers. In reinforced concrete work such couplers instead of lapped reinforcement will reduce congestion of steel at construction and otherjoints and allow the use of more slender concrete members. The outer diameter of these couplers can be designed to be within the permissible tolerances in cover in reinforced concrete work, particularly for deformed type reinforcement. Since conventional couplers have relatively large outside diameters, they often result in larger concrete covers having to be provided along the parent bars, thus increasing the size of concrete members.Due to a variety of reasons, it is desirable to use slender couplers in connecting structural ties, ground anchors etc.
CLAIMS (filed on 3rd Nov 1983)
1. Atechnique of connecting bars togetherwith a coupler, which is characterised by progressively reducing the diameter of the parent bars in calculated steps and correspondingly increasing the wall thickness of the coupler inwards such that the force carrying capacity ofthe coupler at any section along its length is at least equal to the forcetransferredfrom the parent bar to the coupler.
2. A stepped coupling device as claimed in Claim 1, wherein coupler material is the same as the parent bars, the cross-sectional area ofthe coupler at the critical sections is at least equal to the cross-sectional area of the parent barfrom which force is being transferred to the coupler atthat section.
3. Astepped coupling device as claimed in Claim 1 or Claim 2, wherein a desired factor or safety is incorporated in the coupler design by providing larger area of cross-section in the coupler than the parent bars at the critical sections.
4. Astepped coupling device as claimed in Claims f to 3, wherein the connection between the bars and the couplerforforce transfer is established by any conventional method such as by mating screw threads or by squeezing an initiatly oversized coupler onto the bars.
5. Astepped coupling device as claimed in Claims
1 to 4, wherein the lengths ofthe mating surfaces and the details of the transition profiles between these are determined by strain distribution in the connection and by experimental investigations.
6. A stepped coupling device as claimed in any preceding claim, wherein diameters of steps are determined by writing equations forsafe transfer of forces from the bar to the coupler, for any sensibly chosen outer diameter ofthe coupler.
7. A stepped coupling device as claimed in the preceding claim, wherein a desired factor of safety is incorporated at any critical section.
8. Asteppedcoupling device as claimed inthe preceding claim, designedforthefull strength of the barsorfora reduced strength such as is left after cutting threads on a bar.
9. Astepped coupling device as claimed in any preceding claim, wherein the strength ofthe coupler material is different from the parent bars.
10. Forjoining bars of different diameters, a coupling device with stepped diameters as claimed in any preceding claim forthe larger diameter bar and with a single conventional diameterforthe smaller diameter bar.
11. A stepped coupling device as claimed in any preceding claim, wherein the outer cross-sectional of the coupler is hexagonal or octagonal.
12. Forjoining bars of different diameters, stepped diameters as claimed in Claims 1 to 9, are adopted inside the end of the larger diameter bar and on the outside ofthe smaller diameter bar,thus end ofthe largerdiameterbaracting as half of a coupler.
13. A stepped coupling device as claimed in any preceding claim, wherein the final choice of diameters is rounded off to convenient sizes or adjusted in the light of experimental investigations.
14. A stepped coupling device substantially as hereinbefore particularly described and as illustrated in Figures 1 to 4 ofthe accompanying drawings.
New claims or amendments to claims filed on 23rd December'83.
Superseded claims 1 to 14.
New or amended claims: 1. Atechniqueofconnectingsolid barstogether with a couplerfor up to the full strength of the parent bars, which is characterised by progressively reducing the diameter ofthe parent bars in appropriate steps and correspondingly increasing the wall thickness of the coupler inwards, such thattheforce carrying capacity ofthe coupler at any section along its length is at least equal to the force transferred from the parent barto the coupler.
2. A connection as claimed in Claim 1,wherein coupler material is the same as the parent bars, the cross-sectional area ofthe coupler at the critical sections is at least equal to the cross-sectional area of the parent bar from which force is being transferred to the coupler atthat section.
3. A connection as claimed in Claims 1 or 2, wherein a desired factor of safety is-incorporated in the coupler design by providing largerarea of cross-section in the coupler than the parent bars at the critical sections.
4. Aconnection as claimed in Claims 1 to 3, wherein force transfer between the bars and the coupler is achieved by any conventional method such as by mating screwthreads or by squeezing an initially
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (16)
1. Atechniqueofconnectingsolid barstogether with a couplerfor up to the full strength of the parent bars, which is characterised by progressively reducing the diameter ofthe parent bars in appropriate steps and correspondingly increasing the wall thickness of the coupler inwards, such thattheforce carrying capacity ofthe coupler at any section along its length is at least equal to the force transferred from the parent barto the coupler.
2. A connection as claimed in Claim 1,wherein coupler material is the same as the parent bars, the cross-sectional area ofthe coupler at the critical sections is at least equal to the cross-sectional area of the parent bar from which force is being transferred to the coupler atthat section.
3. A connection as claimed in Claims 1 or 2, wherein a desired factor of safety is-incorporated in the coupler design by providing largerarea of cross-section in the coupler than the parent bars at the critical sections.
4. Aconnection as claimed in Claims 1 to 3, wherein force transfer between the bars and the coupler is achieved by any conventional method such as by mating screwthreads or by squeezing an initially
oversized couplerontothe bars.
5. A connection as claimed in Claims 1 to 4, wherein the lengths of each pair of mating surfaces are determined with reference to the efficiency of forcetransferthrough these surfaces.
6. Aconnection as claimed in Claims 1 to 5, wherein the details of the transition profiles between mating surfaces on the bar and inside the coupler are determined by strain distribution in the connection and by experimental investigations.
7. Aconnection as claimed in any preceding
Claim, wherein diameters of steps are determined by writing equations for safe transfer of forces from the bar to the coupler, for any sensibly chosen outer diameter ofthe coupler.
8. Aconnection as claimed in the preceding Claim, wherein a desired factor of safety is incorporated at any critical section.
9. A connection as claimed in the preceding Claim, designedforthefull strengthofthebarsorfora reduced strength such as is left after cutting threads on a bar.
10. A connection as claimed in any preceding
Claim, wherein the strength ofthe coupler material is different from the parent bars.
11. Forjoining barsofdifferentdiameters,a connection which incorporates a couplerwith stepped diameters as claimed in any preceding Claim forthe larger diameter bar and a single conventional diameterforthe smaller diameter bar.
12. A connection as claimed in any preceding
Claim, wherein the outer cross-section ofthe coupler is hexagonal or octagonal.
13. Forjoining bars of different diameters, a connection as claimed in Claims 1 to 10, adopted inside the end of the larger diameter bar and on the outside ofthe smaller diameter bar, thus the end part of the largerdiameter bar itself acting as half of a coupler.
14. A connection as claimed in any preceding claim, whereinthefinat choice of diameters is rounded offto convenient sizes or adjusted in the light of experimental investigations.
15. A connection as claimed in any preceding
Claim, which joinssmooth bars or deformed bars with ribs orsome othertype of indentations on the outer surfaceofthe bars.
16. A connection substantially as hereinbefore particularly described and as illustrated in Figures 1 to 4 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08327112A GB2128704B (en) | 1982-10-12 | 1983-10-11 | Rod coupler |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8229037 | 1982-10-12 | ||
| GB08327112A GB2128704B (en) | 1982-10-12 | 1983-10-11 | Rod coupler |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8327112D0 GB8327112D0 (en) | 1983-11-09 |
| GB2128704A true GB2128704A (en) | 1984-05-02 |
| GB2128704B GB2128704B (en) | 1986-02-05 |
Family
ID=26284094
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08327112A Expired GB2128704B (en) | 1982-10-12 | 1983-10-11 | Rod coupler |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2128704B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0465202A1 (en) * | 1990-07-04 | 1992-01-08 | Garrison Limited | Snooker cue, and device for securing together snooker cue parts |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB355528A (en) * | 1930-06-11 | 1931-08-27 | Dardelet Threadlock Corp | Improvements in sucker rods for deep well pumps and the like |
| GB954409A (en) * | 1962-01-09 | 1964-04-08 | Cable Covers Ltd | Compression connectors for joining or terminating wires, rods and other suitable members |
| GB955914A (en) * | 1961-07-26 | 1964-04-22 | Hans Joachim Fuchs | Improved light metal boring rod and rod connector assembly |
-
1983
- 1983-10-11 GB GB08327112A patent/GB2128704B/en not_active Expired
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB355528A (en) * | 1930-06-11 | 1931-08-27 | Dardelet Threadlock Corp | Improvements in sucker rods for deep well pumps and the like |
| GB955914A (en) * | 1961-07-26 | 1964-04-22 | Hans Joachim Fuchs | Improved light metal boring rod and rod connector assembly |
| GB954409A (en) * | 1962-01-09 | 1964-04-08 | Cable Covers Ltd | Compression connectors for joining or terminating wires, rods and other suitable members |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0465202A1 (en) * | 1990-07-04 | 1992-01-08 | Garrison Limited | Snooker cue, and device for securing together snooker cue parts |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2128704B (en) | 1986-02-05 |
| GB8327112D0 (en) | 1983-11-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19921011 |