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bharat_g SEFI Member
Joined: 16 Nov 2017 Posts: 2
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Posted: Wed Mar 14, 2018 10:19 am Post subject: Clause 5.7.2.2_limiting UTS to YS ratio |
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Generally lower limit (minimum) of UTS/YS ratio is prescribed (like IS 13920:2016 has minimum UTS/YS ratio of 1.15), but this codebook restricts the maximum (upper limit) value of UTS/YS ratio. What might be the reasons for limiting the maximum UTS/YS ratio to 1.25. What happens if the reinforcement has UTS/YS ratio more than 1.25 (satisfying the minimum YS criteria laid down by the codebook)?
UTS: Ultimate tensile strength
YS: Yield strength or 0.2% proof strength
Thanks and Regards
G.Bharat
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darshanpala SEFI Member
Joined: 06 May 2014 Posts: 2
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Posted: Wed Mar 14, 2018 4:32 pm Post subject: Clause 5.7.2.2_limiting UTS to YS ratio |
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Bharat,This is because for a seismic event, the SFRS(Seismic Force Resisting System) is designed to yield, thus giving the building a ductile response. If the actual yield strength is more than the specified yield strength, then the building will attract more force.I believe this is the intent of the clause. However, I believe the expected(actual) yield strength to the specified yield strenght should be limited. Also this should apply ONLY to the elements that are expected to yield viz. longitudinal bars of shear walls, coupling beams, beams of MFs, etc.This has been a standard spec for us in the Los Angeles region. Good to see an attempt made in the IS code as well. Hope this helps. Regards,
Darshan.
From: "bharat_g" <forum@sefindia.org>
Sent: Wed, 14 Mar 2018 21:20:15 GMT+0530
To: econf@sefindia.org
Subject: [E-CONF] Clause 5.7.2.2_limiting UTS to YS ratio
Generally lower limit (minimum) of UTS/YS ratio is prescribed (like IS 13920:2016 has minimum UTS/YS ratio of 1.15), but this codebook restricts the maximum (upper limit) value of UTS/YS ratio. What might be the reasons for limiting the maximum UTS/YS ratio to 1.25. What happens if the reinforcement has UTS/YS ratio more than 1.25 (satisfying the minimum YS criteria laid down by the codebook)?
UTS: Ultimate tensile strength
YS: Yield strength or 0.2% proof strength
Thanks and Regards
G.Bharat
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hemalmistry ...
Joined: 01 Jul 2009 Posts: 70
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Posted: Wed Mar 14, 2018 4:58 pm Post subject: |
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Minimum UTS/YS of 1.15 is to ensure adequate ductily to allow inelastic deformation. Maximum UTS/YS of 1.25 is to ensure ductile flexurall failure rather than brittle shear failure. |
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