Slenderness ratio of column is wrong in Robot

[Μηχανικος]

Hi,

I am cross checking robot design of a column with hand calculation and the first thing i have noticed is that the clear height of the column as well as the effective length of a column is wrongly calculated by Robot.

Clear height of column

as you can see from the picture below the height of the column is 3.0m, and the depth of the beam is 0.55m therefore the clear height of the column, L is 3.0m - 0.55 m = 2.45m

As you can see from the second picture the clear height used by robot is 3.00m which is the whole height of the column.

Effective length of column

Then the effective length of the column, Lo is calculated by:

Lo = L x factor (depending on the fixitity of the column at top and bottom)

possible values of Lo are 

pinned at both ends, Lo = L = 2.45m

cantilever column, Lo = 2 x L = 5.0m

fixed at bottom, pinned at top, Lo = 0.7 x 2.45 = 1.715m

fixed at both ends, Lo = 0.5 x 2.45 = 1.225m

fixed at bottom, roller on top, Lo = L = 2.45m

Considering the fact that Robot calculated the same value for both clear and effective height it means that robot considers the column pinned at both ends or fixed at bottom and roller at top which i think both are wrong.

Anyone knows what is the problem here?

[Μηχανικος]

Additional information

This is a 4-storey Rc building with basement,

The column above is at ground storey, therefore at the bottom of the column there is another column that extends into the basement and also has 4 beams, one at each side of the column.

the same configuration exists at top of column.

[Μηχανικος · Accepted solution]

I found the answer to my own question.

Robot structural analysis does not automatically recognise fixity end conditions of each column therefore the user has to manually setup the end conditions of each member.

This can be done once you are  in the "Provided Reinforcement Module"and have already chosen a member for design,

1. click on the "RC Element" at the top and then choose "Bucking Length" from the drop down menu.

2. Click on the icon with the pencil for each direction to setup the fixity end conditions for each direction.

3. Then select the appropriate fixity end conditions, which already have preset k factors (first 4 options with black colour) or choose the manual configuration (last three options with red colour).

4. With the manual configuration you can manually setup the adjoning bar parameters of the element to be designed.

5. Once in the Adjoining bar parameters window, at the bottom you can choose manual or from structure.

6.