IS 16172-2014 - Standard for Reinforcement Couplers for Mechanical Splices of Bars in Concrete - Specifications

IS 16172:2014

Reinforcement Couplers for Mechanical Splices of Bars in Concrete - Specifications

Class H – Couplers which meet both Low cyclic fatigue test and high cyclic fatigue test requirements shall be classified and Designated as Class H Couplers

Class L – All other Coupler which meets only low cycle fatigue requirements shall be designated as Class L Couplers

 

Grade	Fy (yield strength)	Fu (Ultimate Strength)	% Elongation of Bar (min)
Fe 500	500 N/mm^2	545 N/ mm^2	12%
Fe 500D	500 N/ mm^2	565 N/ mm^2	16%
Fe 550	550 N/ mm^2	585 N/ mm^2	10%
Fe 550	550 N/ mm^2	600 N/ mm^2	14.5%
Fe 600	600 N/ mm^2	660 N/ mm^2	10%

 

 

IS 16172:2014
Type of Test Required	Why ! (purpose of the test)	What is the Criteria ?
Static tensile strength test	Tensile strength of the Rebar joint (Rebar to Coupler Splice) joint	Bar Break > fu (appropriate tensile strength)   Fu = Ultimate tensile strength of bar
Slip Test	Used to make sure that the plastic movement (slip) between the reinforcement bars with in the Mechanical Splice, when Loaded in tension	<=0.10 mm after applying 0.6fy Loading   fy= Yield Strength of bar
Uniform Cyclic Load Test (Seismic Elastic)	Used to make sure how a mechanical splice performs when subjected to alternating tension and compression loads for a given number of cycles.   Each cycle may exceed the specified yield strain of the reinforcement bar and is intended to stimulate an earthquake loading.	100 Cycles of stress variation from 5% to 90% of fy (fy=550N/mm^2) Frequency 0.70 Hz for bar below 36mm diameter and Frequency 0.50 Hz for bar above 36mm diameter. NO LOSS OF STATIC TENSILE STRENGTH CAPACITY
Fatigue Loading
Low Cycle Fatigue Test	The purpose of this test is to evaluate the performance of the splice reinforcement following significant inelastic stress reversal fatigue cycle which would stimulate a seismic event, This includes a series of elastic stress reversal cycle followed by increasing inelastic stress reversal cycle out to 5 times the yield point strain of the reinforcement being tested.   In other words the purpose of fatigue testing of mechanical splices for steel reinforcement bars is to determine the fatigue strength of the mechanical splice.   The fatigue performance of a mechanically spliced bar will normally be lower than that of the un-spliced bar.	10,000 cycles of alternating tension and compression load of 173 MPa.   Frequency shall be 0.083 Hz for Bar diameter above 36mm and Frequency shall be 0.35 Hz for bar diameter less than 36mm – MUST FOR CLASS H AND L COUPLERS
High cycle fatigue test	Similar to a cyclic load test, but with the test load staying below the yield strength of the bar. The test is conducted until failure or a specified number of cycles are reached.   The test is meant to stimulate a mechanical splice in a bridge or other structure subjected to frequent elastic load cycles.   High cycle Fatigue is the term used to designate the situation when more than 1,000 to 10,000 cycles are need before final rupture.   In this case average stresses are usually below the yield strength of the material, and most of the time is spent to initiate a crack.   High cycle fatigue is a type of fatigue caused by small elastic strains under a high number of Load cycle before failure occurs   The stress comes from a combination of mean and alternating stresses. The mean stress is caused by the residual stress, the assembly load, or the strongly non uniform temperature distribution.	2,000,000 (2 million) cycles of varying axial tensile load with stress ranges, 2σa of 60 N/mm^2 without failure.   The upper stress , in the test shall be 0.6 Where =550 N/mm^2   The frequency of load cycles shall be constant during the test and shall be between 1Hz and 200 Hz – MUST FOR CLASS H COUPLERS
Maximum % Elongation		3%

 

For IS 16172:2014 is a Manufacturers code for production of Couplers,

Couplers should be designed for Fe550 grade as a standard. The performance of the mechanical splice is to be determined with reference to IS 1786:2008 and IS 456:2000

Even if the coupler is designed for higher grade of Rebar and has capacity, the Cyclic & Tensile test will not reflect the site conditions.