Structural analysis terminology: The diagram that shows how the axial (thrust) force varies along the span of a beam or frame member is called:

Introduction / Context:
Engineers represent internal actions along members using standard diagrams. Besides shear and moment, some members (beams with axial load, frame members, arches) also carry axial force, commonly called thrust.

Given Data / Assumptions:

• A member may carry axial force in addition to shear and bending.
• Axial force is taken as positive in tension (or as defined by sign convention).
• Small deformation theory; statics-based evaluation.

Concept / Approach:
The axial force at a cross-section is the algebraic sum of projections of all external forces on the member’s axis to the left (or right) of that section. Plotting this value versus position produces the thrust (axial force) diagram.

Step-by-Step Solution:
Cut a section at distance x, write ΣF_along_axis = 0.Evaluate the axial force N(x) at that section.Repeat along the length to obtain N(x) distribution; plot it to get the thrust diagram.

Verification / Alternative check:
For a pure beam with no axial loads, the thrust diagram is identically zero; for frames or members with axial loads, the diagram shows nonzero values.

Why Other Options Are Wrong:
Bending-moment/Shear-force diagrams plot M(x)/V(x), not axial force.Stress diagram is not a standard internal action plot name in this context.Load diagram shows external w(x) or point loads, not internal thrust.

Common Pitfalls:
Confusing sign conventions or mixing axial force with shear force due to poor axis definition.

Final Answer:
Thrust diagram.