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Re: Preliminary sizing as per CAN/CSA-16-01

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> From: Ritesh Patel <ritesh758(--nospam--at)>

> My question is regarding preliminary sizing of the beam-column as per
> CAN/CSA-16-01.
>   In the Canadian Handbook of Steel Construction, in the table 4-4,
>   different values of  Cf /# Cy (ratio) are given for different classes (1
>   to 3). For selection of columns, this ratio should be equal to 1.0. For
>   beams ( no axial compression) this ratio should be minimum. For
>   beam-column element again this ratio should approach to 1.0. Am I
>   correct ?

The Cf/(phi*Cy) ratio is intended to reduce the web class for BENDING in
Beam-Columns when there is axial loading (see Table 2 and Table 4-2).
The higher the ratio, the lower the web/section class for BENDING. As
the ratio approaches 1.0, you lose bending capacity in the beam
analysis. You do not want a web ratio approaching 1.0 for your
preliminary selection for a beam column.

There is no such web Class ratio for pure axial load. Table 1 provides
the upper limit for web width-thickness. Use Table 4-4 for limiting unit
stress at controlling KL/r or Table 4-7 for limiting unit stress at
Euler buckling load. Use the column tables in the GREEN pages if you
already know your factored axial load. 

R. Paul Ransom, P. Eng.
Burlington, Ontario, Canada
<mailto:ado26(--nospam--at)> <>

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