For a steel column subjected to combined axial load and bending, how does the interaction diagram visually represent the acceptable limits of these combined stresses, and what does a point outside the diagram signify?

For a steel column subjected to combined axial load and bending, an interaction diagram is a graphical representation illustrating the column's ultimate capacity to resist these combined forces. The diagram typically plots the axial load (P), which is a force acting along the column's longitudinal axis and usually compressive, on the vertical axis, and the bending moment (M), which is a force causing the column to bend or flex, on the horizontal axis. The curve drawn on this diagram connects all the specific combinations of axial load and bending moment that the steel column can resist at its ultimate strength before failure. The region *enclosed by this curve and the axesvisually represents the acceptable limits of these combined stresses. Any point falling *withinthis boundary signifies that the column has sufficient capacity to safely carry the applied axial load and bending moment without reaching its ultimate limit state, indicating a safe and compliant design. The curve itself defines the column's ultimate capacity boundary, meaning any point on the curve represents the maximum permissible combination of P and M the column can sustain. Conversely, if a point representing the applied axial load and bending moment falls *outsidethis interaction diagram's boundary curve, it signifies that the combined stresses exceed the column's ultimate resistance capacity. This indicates that the column will *failunder those specific applied loads, as its material strength and structural integrity are insufficient to resist the demand, leading to an unsafe condition or collapse.