Type II Couplers - Different Types

Question

Type II Couplers - Different Types

EngineerRam (Structural)

(OP)

6 Aug 24 01:04

Hello,

Recently we received a submittal from a contractor to use a Type II coupler that I have never seen before. The product is similar to the below link:

https://www.alibaba.com/product-detail/22mm-25mm-3...

Seems to be that it works analogously to a prestressing chuck. However, I have reservations about this coupler in compression. All of the literature I am seeing does not appear to have any testing in accordance with American or Western standards.

Has anyone used these couplers for rebar? What are your thoughts?

Thanks

EngineerRam (Structural) · Answer 1 · 2024-08-06 01:18:06

Adding on to this, I am working in a high seismic area, so consideration must be taken to load reversal must be taken. I am inclined to reject these.

TigerGuy (Geotechnical) · Answer 2 · 2024-08-06 14:57:46

It looks like compression load is carried by the connected bars being in direct contact. I would be most interested in the tension failure mechanism.

Heaviside1925 (Mechanical) · Answer 3 · 2024-08-06 15:29:09

I would be in agreement with your inclination to reject. Without substantial test data, even if it does perform as advertised, it would be difficult to justify its usage. These remind me of the SharkBite plumbing fittings. I wonder if these will end up in HomeDepot for weekend warriors who don't want to use tie wire.

TigerGuy (Geotechnical) · Answer 4 · 2024-08-06 17:28:07

Are they trying to avoid using these? https://www.trusupply.com/rebar-couplers.html

With this type of coupler, tensile failure occurs within the bar long before the coupler yields. If the proposed couplers have similar, verifiable test data available, it is something to consider.

You stated your concern is the performance of the coupler in compression. I don't think I understand that concern.

Ingenuity (Structural) · Answer 5 · 2024-08-31 18:56:36

This coupler looks vey similar to a prestressing wedge chuck, as you stated.

With a wedge chuck there is a take-up load that needs to be applied to engage and displace the wedges (4 pieces in this case) so they are correctly seated to take the intended TENSION load. In prestressing strand applications this is called 'back seating' and is necessary part of the chuck installation.

If the chuck is back seated (the wedges move a small amount) then upon load reversal (compression), there will be a small amount of movement (backwards) until the parts touch and go into bearing.

I am not sure how you would 'backseat' the chuck in the rebar coupler application given it is in the field with adjacent bars etc.

You are in GUAM (US territory) - ask the contractor for ICC approval cert. If no cert, reject.

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Type II Couplers - Different Types