k Factors

Can anyone guide me in the checking of k factors in STAAD.Pro??? Since I'm using STAAD in the analysis and design of buildings I didn't check the k,effective length factors of column, so i rely on the built in calculation of the software....

Hello,

The calculation of the effective length factors are done based on a paper titled ‘Compression Members’ presented by George Tsiatas. If it produces a conservative or a non-conservative factor, you may change it to the value you desire.

Alternatively, you could analyze the model per the current AISC code (360-05) which recommends the Direct Analysis method if you wish to avoid using K factors.

Hello Bikash,

I am working with Staadpro software only for the last one year. You can safely assume that I am new to the field. I am working with Indian Code in which the effective length facotor(Table 28 - compression member) based on the fixity at the two ends of the column has been laid down. The factor is both less than 1 and more than 1  depending on the fixity at the two ends of the column. Staad by default ,in absence of any parameter for the K factor  provided by the user, considers the K factor as 1. I assume so. Will you please let me know whether the vlaues of K laid down in the code need be input for designing the column or the Staad will consider the K factor on its own based on the fixity condition prevailing in the model. Consideration of K factor as 1(default value)  for rigid joints between beams and columns in frame structure may produce over conservative design, that is my opinion. Will you please throw some light in the matter to guide me as to it would be in order to  put in the 'K' value by the designer per codal provision or default K value should be accepted. It would not be out of place to mention that most of the designers are accepting the default K values in the analysis and design of frame structures.

I look forward to your valuable guidance.

sureshprsharma