Design of Short Columns Subject to Axial Load and Bending - Design of Reinforced Concrete - page 290

Figure 10.11 Interaction curves for a
rectangular column with different sets of
reinforcing bars.

10.5 CODE MODIFICATIONS OF COLUMN

INTERACTION DIAGRAMS
If interaction curves for P n values were prepared, they would be of the types shown in
Figures 10.10 and 10.11. To use such curves to obtain design values, they would have to
have three modifications made to them as specified in the Code. These modifications are
as follows:

(a) The Code 9.3.2 specifies strength reduction or factors (0.65 for tied columns

and 0.70 for spiral columns) that must be multiplied by P n values. If a P n curve
for a particular column were multiplied by , the result would be a curve some-

thing like the ones shown in Figure 10.12.

Figure 10.12 Curves for P n and P n for a
single column.