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RCC Column Interaction Diagrams
P-M interaction diagrams are generated for major and minor axes of rectangular columns subjected to bending moment and axial compression or tension for a range of reinforcement values.
The diagrams are constructed by locating the following points on the interaction diagram:
Linear interpolation is used up to decompression point. Points beyond this are calculated by increasing depth of neutral axis in small steps.
Reinforcement may be input as
For the 12"x24" (300x600 mm) column section shown above, reinforced with 1" (25mm) nominal dia bars, steel may be given as 7.854, 2.73% or #8 (4908, 2.73% or 25mm).
Multiple values, separated by a blank space may be entered for reinforcement.
Thus, for a preliminary assessment of column capacity, reinforcement may be entered as percentage of gross concrete area, 1% 2% 3% 4% whereas for selection of bars, reinforcement may be entered in terms of diameters, #6 #7 #8 16mm 20mm 25mm etc.
On output, P-M curves are displayed for each value of reinforcement.
© 1999-2004 Rudra Nevatia