Bracing between primary members designed to resist cross-sectional deformation and distribute part of vertical load is known as what?

• A. Diaphragm
• B. Secondary Member
• C. Tie Beam
• D. Stiffener

Answer: (B)

This question is about how frame elements contribute to keeping the structure stiff and transferring loads. A brace that runs between the main members to keep their cross-sections from distorting and to share part of the vertical load is best described as a secondary member. It isn’t one of the primary load carriers like a main girder, but it ties the primary members together, increasing frame stiffness and helping distribute vertical forces.

A diaphragm, by contrast, is a broader floor or wall element that resists lateral shear and helps transfer loads across the frame; a stiffener reinforces local plate buckling; a tie beam resists horizontal thrust in arches or frames. The described bracing fits the role of a secondary member.