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L/T shaped column

 
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perwez at lntecc.com
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PostPosted: Tue Dec 19, 2006 5:43 am    Post subject: L/T shaped column Reply with quote

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





PostPosted: Tue Dec 19, 2006 8:36 am    Post subject: L/T shaped column Reply with quote

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

Posted via Email
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