For webs of standard steel sections, identify the incorrect statement about gross web area definitions for rolled I-beams, channels, and plate girders.

Introduction / Context:In steel design, quick estimates of web area use simple geometric products of web depth and web thickness. These gross areas support preliminary shear and buckling checks before refined deductions for fillets, holes, or cope details are considered.

Given Data / Assumptions:

• We are dealing with gross (not net) web areas.
• Rolled I-beams and channels have defined web thicknesses and overall depths.
• Plate girders have separate web plates with explicit plate depth and thickness.

Concept / Approach:

Gross web area is taken as depth * thickness for the web element. For rolled shapes, the “depth” used for gross approximations is the overall section depth; for plate girders it is the clear web plate dimension. Net deductions (e.g., for copes/holes) are handled later if required.

Step-by-Step Solution:

Verification / Alternative check:

Design manuals may refine “effective” web depth for buckling or shear lag, but that does not invalidate the gross definition used for initial sizing.

Why Other Options Are Wrong:

• A–C: Each reflects the standard gross-area estimate.
• E: True in many preliminary calculations and does not contradict A–C.

Common Pitfalls:

• Confusing gross and net section properties; deductions apply to net, not gross.
• Mixing up clear web depth (between fillets) with overall depth without noting which idealization is used.

Final Answer:

None of these.