Cutting holes in beam webs is common for running mechanical, electrical, or plumbing services but

must be done carefully to avoid weakening structural integrity.

Holes should be located near mid-span supports (points of low bending moment and high shear) to

reduce impact on beam bending strength.

Holes should not be located near areas of maximum bending moment (typically mid-span between

supports), because this is where the beam experiences maximum tension or compression.

Locations 2 and 4 are at or near the beam supports (shear zones), and generally small holes can be

cut there, following size limits and reinforcement guidelines.

Locations 1, 3, and 5 are closer to mid-span or areas of high bending stress, so holes here risk

compromising the beam’s moment capacity.

Reference:

NCARB ARE 5.0 Review Manual, Structural Systems chapter

Steel construction and beam design guidelines (AISC)

Building codes and structural engineering best practices for web penetrations