During design of a concrete column member using IS456 code, user can specify the face of the column for longitudinal bar arrangement using the RFACE parameter. There are three options available for RFACE parameter as --
The default value is 4 which indicates that program will arrange the longitudinal reinforcement bars equally at four faces of the column.
RFACE 2 and RFACE 3 parameter can be described as --
RFACE 2 implies bars placed along the 2 edges parallel to local Z axis
RFACE 3 implies bars placed along the 2 edges parallel to local Y axis
Consider the following column member with dimension 250mmX700mm specified as--
1 PRIS YD 0.7 ZD 0.25
To arrange the reinforcement bars only in the longer face of the column (which is parallel to the local Y axis), RFACE 3 parameter should be assigned to this member.
Now consider the same column with YD and ZD values reversed as--
1 PRIS YD 0.25 ZD 0.7
To arrange the reinforcement bars only in the longer face of the column (which is parallel to the local Z axis), RFACE 2 parameter should be assigned to this member.
For simpler explanation, if you want to place the reinforcement bars along the longer edge of a rectangular column, you should define the following—
If ZD > YD, then specify RFACE 2 parameter.
If YD > ZD, then specify RFACE 3 parameter.
NOTE: It is normal practice to consider the local Z axis of the column as the major axis (i.e specify YD value greater than ZD value). If the column orientation is different from this condition, BETA angle is specified to rotate the local axis orientation.