Which statement about truss force directions is true?

• A. All members experience compression
• B. The bottom chord is typically in tension while the top chord is in compression
• C. Web members carry torsion
• D. Diagonal members are non-axial

Answer: (B)

In a typical pin‑jointed truss, each member carries only an axial force along its length (two‑force member behavior). When a vertical load is applied, the top chord tends to be squeezed between joints, so it carries compression, while the bottom chord tends to be pulled apart, so it carries tension. The web (diagonal and vertical) members transfer these forces between the chords and also act axially; they do not transfer torsion. This is why the statement about the bottom chord in tension and the top chord in compression best matches how a common truss behaves under loading. Other ideas—such as all members being in compression, web members carrying torsion, or diagonals being non-axial—do not fit the axial-force model of a pin‑jointed truss.