Q: ETABS 9.6 is giving me very high effective length factors for columns for Indian design code? What could be the reason behind it?
A: In ETABS 9.6 and later versions effective length factors are computed based on Wood’s Charts as required by IS:456. So the effective length computed by ETABS is same as required by IS:456. The effective length of a column depends on how much rotational stiffness is available at column ends. If the effective length is coming too high please check the flexural stiffness of beams connected to it. In most cases program will be able to compute effective length factors correctly even for those columns which are of double height or receive numerous beams in the story height. If you come across a case when effective length factor doesn’t appear correct then you can use Design overwrites to assign it manually.