In a truss, the top member primarily carries which type of force?

• A. Tension
• B. Shear
• C. Compression
• D. Bending

Answer: (C)

In a truss, members are treated as two-force members that carry only axial loads with pin connections. When a truss is loaded from above, the geometry makes the top chord push its joints toward each other, generating a compressive force in the top member. At the same time, the bottom chord tends to be pulled apart, so it carries tension. The diagonal web members carry either tension or compression to transfer the load through the truss. Since bending and shear are not the primary actions in an ideal pin-connected truss, the top member ends up being in compression under typical loading. (Note: different loading or non-pin joints can change this, but compression is the usual case for the top member.)