Rebar Coupler Standards & Addressing the major Concern and Performance Parameters

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Rebar Coupler International Standards 

 

Lets List down the Standards first !!!

IS 16172 : 2014                 Click here..

ACI 318 / ACI 133              Click here..

BS 8110                            Click here..

ISO 15835 & NF 350-20      Click here..

CALTRANS                         Click here..

TEXAS DOT                       Click here..

 

Couplers should be Designed and Manufactured in Compliance with these Standards

 

·       Full tension splice : Satisfying codal load requirement

·       Maintain full ductility of reinforcement

·       Easy Installation, No Torque wrench required

·       Bar Coupler Should fit all Splicing Requirement

·       Manufacturing under strict Quality Assurance Plan

·       Full traceability of material origin and production batch

·       Type 2 Coupler suitable for Seismic Area

·       Solves Bar Congestion problem

·       No Staggering of Splice bars





Parameters - affecting the Performance


Major Parameter and concern which would affect the Coupler Joint that needs to be addressed :

 

Grade of Rebar :

The Reinforcement steel supplied on site should be kept consistent for a site as per specified design criteria,

If there is any variation in the grade of the rebar, especially in case of Re-rolled steel. 

If there is a error in Chemical Composition of the rebar or if there is a presence of cavities in the steel, it is possible for the rebar to exhibit variation such as reduction in joint strength, issue with bending/re- bending of steel and cracking of the rebar during threading/upsetting operations.


Ductility :

It is usually believed that the higher the ducility of the bar, the better is the execution.

While in IS 1786 code prescribes in minimum ductility, there is no upper limit for the same.

A very High ductile bar can cause issues such as faster neck formation of the joint during tensile test in the plastic zone and slippage of threads leading to early breakage.

The ductility of the bar would help and provide performance in cutting and bending but does not help in Mechanical Splicing.

 

Size and shape of Rebar:

Sometimes the rebar provided and manufactured is not in circular shape or skewed in appearance, In such case, the threading appearance on the rebar may seem uneven.

Care should be taken in such variation in designing the couplers and use of types of Couplers

 

Rib Size:

The cross section of a rebar is measured theoretically by weighing the standard length and then calculating the apparent area of the rebar. If the ribs are excessive,

The core circumference of the Rebar would be smaller as compared to another rebar with smaller ribs and having the same weight.

This would lead to under sizing of the rebar for threading and can lead to play in the coupler/Mechanical splice joint and lower ultimate strength

 

Coupler material

Coupler material should be in complies with Material Composition, Properties and Specification’s

Coupler should always meet criteria higher than the threshold limit of the Rebar,

Coupler material physical and chemical properties also determines joint strength and are to addressed and monitored by testing.


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