Need a book? Engineering books recommendations...

# RE: "Big Column and small beam" Rule

• To: seaint-seaosc(--nospam--at)mail-list.com
• Subject: RE: "Big Column and small beam" Rule
• From: "Alex C. Nacionales" <acnacionales(--nospam--at)gmail.com>
• Date: Sun, 29 Mar 2015 12:23:59 -0700
• List-subscribe: <mailto:SEAINT-SEAOSC-on@mail-list.com>

Rizwan,

question. If the beam is connected to a RC slab,  then part of the slab width
could be considered as part of the beam- ( T-beam or half T-beam for exterior
frames). How could a hinge form in the beam with the RC slab connected to
it?

Thanks again.

Alex Nacionales
Vancouver, BC

-----Original Message-----
From: seaint-seaosc(--nospam--at)mail-list.com [mailto:seaint-seaosc(--nospam--at)mail-list.com] On
Behalf Of Rizwan Mirza Sent: March 28, 2015 8:14 AM
To: seaint-seaosc(--nospam--at)mail-list.com
Subject: Re: [SEAINT-SEAOSC] "Big Column and small beam" Rule

Following is my humble opinion:

a) The presence of a strong diaphragm just means that all members of the
vertical structural sub-system (columns and shear walls) would undergo the
same deformation in the horizontal plane (the plane of the slab, or the rigid
diaphragm, as it would be called). The result would be that the lateral
load would be resisted by the various members of the vertical structural
sub-system in the proportion of their stiffness. The principle that we must
have strong columns and weak beams does not flow from here and has no relation
to the presence or absence of a rigid diaphragm.

b) For gravity loads, if you increase the stiffness of the columns the support
moments would increase while the span moments would decrease. This would
continue to happen till such time that the support moments are equal to w
L^2/12. But at this value of moment, the columns is likely to have a fairly
large cross-sectional depth for resisting the applicable bending moments.

c) Suppose you do do not wish to achieve such large column cross-sections,
you would have end-moments less than w L^2/12, as computed from elastic
analysis.

Truncated 2148 characters in the previous message to save energy.

-------------------------------------------------------------------------
Post your message to the list by sending it to:
SEAINT-SEAOSC(--nospam--at)mail-list.com.

The email messages sent to the list will be saved in an archive on the World Wide Web.
These archives are located at:
http://archive.mail-list.com/SEAINT-SEAOSC

To contact the list owner, send your message to:
SEAINT-SEAOSC-list-owner(--nospam--at)mail-list.com.

Sponsored By: Pacific Structural & Forensic Engineers Group, Inc. (PSFEG)