I am Trying to make Group Column in RCDC of same Size, Grade of concrete, Steel and of same bars but it is showing error. Please check it.
From the snip it appears that columns C1 to C5 are between levels from -1.32m to 3.2m where as columns C6 and C7 are between levels -1.32m to 6.4m.
Whenever there is difference in levels it is not correct way of grouping as the levels are not same and so RCDC won't group.
Instead try grouping columns C1 to C5 in a group and columns C6 and C7 in another group. That will be correct and so RCDC will do it.
r2 column design.rar