## Calculation of sway and non-sway for K value

## Calculation of sway and non-sway for K value

(OP)

Dear experts,

In order to calculate(K) for design columns , i have to know first type of building (sway or non-sway) and as per the etabs manual design software takes k=1 as a default , and he gives an option to the user to change the value as per section 10.10.1 ACI318-08 , so shall i calculate sway and non-sway manual by calculating Q-index and put values of K for each columns ?

Thank you for help

In order to calculate(K) for design columns , i have to know first type of building (sway or non-sway) and as per the etabs manual design software takes k=1 as a default , and he gives an option to the user to change the value as per section 10.10.1 ACI318-08 , so shall i calculate sway and non-sway manual by calculating Q-index and put values of K for each columns ?

Thank you for help

Thank you

## RE: Calculation of sway and non-sway for K value

Per ACI 318-14 section 6.6.4.3:

a) The increase in column end moments due to 2nd order effects is less than or equal to 5% (in which case it's considered a non-sway frame).

b) The Q value doesn't exceed 0.05.

It's really two sides of the same coin. It's just two different ways of calculating / estimating the ratio of 2nd order deflection / 2st order deflection.

## RE: Calculation of sway and non-sway for K value

For non-sway it is already conservative K=1 by software default , the main problem if the building is non-sway so maybe the value of k is more than 1 and I am sure many engineers did not concentrate on this point and keep the value same.

Thank you

## RE: Calculation of sway and non-sway for K value

For non-sway it is already conservative K=1 by software default , the main problem if the building is sway so maybe the value of k is more than 1 and I am sure many engineers did not concentrate on this point and keep the value same.

Thank you

## RE: Calculation of sway and non-sway for K value

That chart using the following to values:

Sum (EI/L)_columns / Sum (EI/L)_Beams.

You do this for each floor span of the column.... then using the alignment chart to come up with the K factor for the column. That being said, the standard values are the following (for sway frames):

Fixed - Fixed: K = 1.2

Pinned-pinned: K = 2.0

Fixed - Free: K 2.1

If you enter the value for K as 0 in ETABS, I believe that means that the program will automatically calculated it based on the procedure described using the alignment charts. Though I have to admit, I'm more familiar with the way this is done for steel design.

## RE: Calculation of sway and non-sway for K value

Thank you