The Growing Usage of Rebar Couplers

For many years, use of mechanical couplers to splice reinforcing bar has been regarded as a means of reducing the use of long bars. More recently, engineers and installers have recognised the benefits of using couplers to increase construction speed, improve productivity and simplify design details. There are numerous mechanical splicing systems available for use on rebar, many with elements of strength and/or operational compromise

The following classifications embrace most of the systems on the market.

Tapered thread

Tapered thread mechanical couplers are the most popular form of rebar coupler. They are a simple and effective method of connection: opposing bar ends have a tapered thread and are joined using an internally threaded sleeve. A variation of the standard form of coupler, incorporating a stud section, is used to cater for applications where bars cannot be rotated. The angle of the taper varies, depending on the system, but in general does not exceed an included angle of 12. When applied to quenched-and-tempered bar, a proportion of the tapered thread can cut into the softer, more ductile bar core, particularly with the 12 deg angle. Performance tests on shorter, steeper-angled taper threads indicate a tensile capacity up to 95% of the parent bar strength. Longer, shallower angles can give full parent bar strength, but tend to average around 97%.

Quality assurance procedures require couplers to be tightened on to the bar ends with torque wrenches.

Correct installation is verified by visual inspection. There is no requirement to apply a specific torque to the bars to achieve a full-strength splice. Rigorous mechanical testing has produced results demonstrating that joint strength is equal to the strength of the rebar.

BENEFITS

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1. REDUCES REBAR CONGESTION .
2. MORE NO OF REBARS CAN BE ADDED WITHIN SAME CROSS- SECTION.
3. DIREECT LOAD PATH CONTINUITY.
4. DEVELOPS REBAR SPLICE STRENGTH INDEPENDENT OF CONCRETE STRENGTH & CONDITIONS.
5. HUGE STEEL SAVING DUE TO OVERLAP LENGTH (50D) . NEARLY 30-40% SAVING COMPARED TO LAP LENGTH.

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