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Re: what is the allowable beam opening?

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Title: Re: what is the allowable beam opening?
I do not recall anything one way or the other in ACI 318, but my memory is not what it used to be.  :)

In general, I would just make sure you understand how the code provisions work and put that to use.  For example, ACI makes use of Whitney’s stress block.  Thus, in theory, as long as your hole is the distance “c” below the top of the beam (i.e. Below the neutral axis) and leaves enough room for the flexural bars to be developed in the bottom and the hole does not interfere with the shear stress transfer from the top of the beam to the bottom of the beam, then it should be OK.  From a flexural point of view, the concrete below the neutral axis does not “exist” for flexural strength calcs.  Of course, it is VERY important for shear stresses.

Not sure if that helps or not.


Adrian, MI

On 10/22/09 6:22 PM, "Conrad Harrison" <sch.tectonic(--nospam--at)> wrote:

From memory the middle third of the beam depth. But otherwise design the beam for the hole.

Conrad Harrison
B.Tech (mfg & mech), MIIE, gradTIEAust

South Australia

From: Noy Tiglao [mailto:hou69noy(--nospam--at)]
Sent: Friday, 23 October 2009 05:14
To: seaint(--nospam--at)
Subject: what is the allowable beam opening?

what is the allowable beam opening for MEP utilities to pass or penetrate through concrete beam? is there any probition in the code that allows opening or holes in beam? thank you.

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