ABSTRACT
The strength evaluation process is illustrated in Figure 24.1 for one particular strain distribution, where a location of the neutral axis is selected, the corresponding strains, stresses, and forces of reinforcements and concrete can be calculated appropriately to determine the axial load capacity, Pn and bending moment capacity, Mn = Pn · e, about the plastic centroid of the cross section [1].
Introduction ....................................................................................................................................447 Strength interaction of concrete columns ......................................................................................447 Strength interaction behavior of concrete columns internally reinforced with fiber reinforced polymer bars .................................................................................................449 Design of FRP Reinforced Concrete Columns .............................................................................. 450 Slenderness effect .......................................................................................................................... 455 Notations ........................................................................................................................................ 455 References ...................................................................................................................................... 455
These values of Pn and Mn represent one point on the interaction diagram. Additional points on the interaction diagram can be generated by repeating aforementioned procedures with additional locations of the neutral axis or other depths c, each yielding a unique set of Pn and Mn. The ultimate or maximum compressive strain at the outermost extreme compression fiber of concrete is generally set to be 0.003 per ACI 318-11 Code [2].
