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perwez at lntecc.com Guest
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Posted: Tue Dec 19, 2006 5:43 am Post subject: L/T shaped column |
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Dear All
Your point of view is required related to some ambiguities associated with L/T shaped column. Based on your rigorous experience and knowledge, please provide your feedback.
Best regards,
Perwez Ahmad
+91-9840619804
Queries
1. Slenderness limit for short column is given in terms of Lex/D and Ley/b (IS 456:2000, Clause 25.1.2). It is fine for rectangular and circular column. But when it comes to non-rectangular columns, this limit can be fixed in terms of effective length and radius of gyration Le/r only. For rectangular column r — 0.3D, hence Le/r — 40. As per ACI 318-02, clause 10.12.2 -10.12.3,
o For unbraced columns,
o For braced columns, , M1 and M2 are the numerically smaller and larger moments respectively.
For braced column bent in single curvature, Le/r range lies 22-34 for being short column. While for braced column bent in double curvature, this range will be 34-40 (As it shall not exceed 40).
So what limit we should follow Le/r — 40, or as per ACI?
2. Minimum eccentricity for rectangular/circular column as per IS 456:2000, Clause 25.4, is
.
S N Sinha is using same formula in his Hand Book (Page-258) for L-Shaped column. Although as per SP-24 (clause 24.4), minimum eccentricity for non-rectangular section can be calculated as pr below,
emin = maximum(Le/300, 20mm)
Which one should be followed?
3. Additional moment for slender column are calculated as per Clause 37.9.1 (IS 456:2000),
Is above formula valid for L/T column also? S N Sinha is using same formula in his hand book.
4. Design software assumes that forces are applied about CG of section. But in actual practice, forces may be eccentric; especially in case of L/T column. Will it have significant effect?
DISCLAIMER: This Message and its contents is intended solely for the addressee and is proprietary.Information in this mail is for L&T Business Usage only. Any Use to other than the addressee is misuse and infringement to Proprietorship of L&T ECC.If you are not the addressee please return the mail to the sender.L&T ECC DIVISION
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perwez at lntecc.com Guest
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Posted: Tue Dec 19, 2006 8:36 am Post subject: L/T shaped column |
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Dear All
Your point of view is required related to some ambiguities associated with L/T shaped column. Based on your rigorous experience and knowledge, please provide your feedback.
Best regards,
Perwez Ahmad
+91-9840619804
Queries
1. Slenderness limit for short column is given in terms of Lex/D and Ley/b (IS 456:2000, Clause 25.1.2). It is fine for rectangular and circular column. But when it comes to non-rectangular columns, this limit can be fixed in terms of effective length and radius of gyration Le/r only. For rectangular column r — 0.3D, hence Le/r — 40. As per ACI 318-02, clause 10.12.2 -10.12.3,
o For unbraced columns,
o For braced columns, , M1 and M2 are the numerically smaller and larger moments respectively.
For braced column bent in single curvature, Le/r range lies 22-34 for being short column. While for braced column bent in double curvature, this range will be 34-40 (As it shall not exceed 40).
So what limit we should follow Le/r — 40, or as per ACI?
2. Minimum eccentricity for rectangular/circular column as per IS 456:2000, Clause 25.4, is
.
S N Sinha is using same formula in his Hand Book (Page-258) for L-Shaped column. Although as per SP-24 (clause 24.4), minimum eccentricity for non-rectangular section can be calculated as pr below,
emin = maximum(Le/300, 20mm)
Which one should be followed?
3. Additional moment for slender column are calculated as per Clause 37.9.1 (IS 456:2000),
Is above formula valid for L/T column also? S N Sinha is using same formula in his hand book.
4. Design software assumes that forces are applied about CG of section. But in actual practice, forces may be eccentric; especially in case of L/T column. Will it have significant effect?
DISCLAIMER: This Message and its contents is intended solely for the addressee and is proprietary.Information in this mail is for L&T Business Usage only. Any Use to other than the addressee is misuse and infringement to Proprietorship of L&T ECC.If you are not the addressee please return the mail to the sender.L&T ECC DIVISION
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