design of compression member 1

[kaffy]

Hi guys.

I am working on a column design. Since I am using A36 W column (36000 psi), I couldn't find it in table 4-1 (which has only 50 KSI). So I am using Table 4-22(Available Critical stress for compression members). I also checked local stability based on limiting width to thickness ratio (both Web and flange).
Is there anything else I am missing?

Thank You
A newbie

 

[phamENG]

1) Where on earth did you find an A36 Wide Flange shape? A992 has been common for over 20 years, and A572 Gr. 50 was in use well before A992 was adopted.

2) Don't rely on tables. If you're designing to AISC, use Chapters E, F, and H.

 

[ProgrammingPE]

Table 4-22 - Available Critical Stress for Compression Members is just a table created using Equations E3-2, E3-3, and E3-4. It sounds like your shape does not have any slender elements, so Section E3 should apply.

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[phamENG]

While I agree with ProgrammingPE that E3 is going to be the most important part of the design, keep in mind that virtually no real structural element is purely an axially loaded member. Your case might be such that you can neglect flexure, but even in a "leaning column" it may make sense to consider the eccentricity from any P-Delta in the analysis and the resulting combined axial and flexural effects.

 

[kaffy]

@Pham the loading condition is fixed free and I only have concentric axial compressive load.

 

[kaffy]

@ProgrammingPE, As Table 4-22 is output of E3-2, E3-3, E3-3 so following the table means I am already following E3. Is that not right?

 

[kaffy]

@phamENG, I will reconfirm the material properties but based on previous conversation, I was told it is a36.

 

[phamENG]

Within the limits of the tables, sure. But if you need to ask the question about what checks are required, you should do those checks at least once before relying on tables to do it for you. It's like the 1960's version of relying on the computer to do it for you before you know how.

 

[kaffy]

Oh I see. I will run those checks as well. thank you very much both. Very helpful.

Have a good day

 

[JLNJ]

Fixed-free is an idealized condition not often encountered in typical steel framing. Columns are important. Know what you are dealing with or work with someone who does.

 

[kaffy]

Hi JLNJ. I am attaching the file. So I actually have a column which is further attached to spring. That spring will be acting as buffer and load will be hitting the buffer in very worst case scenario. The column will be attached to floor with base plate. So it is fixed on one end and free on other end.

Also fixed free has the biggest value of K which means biggest Kl/R and eventually lowest allowable capacity.