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

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Dear Ritesh :

Following shows the some of the useful tips which may be considered
for Preliminary design of beam-column as per CAn/CSA-16-01. All ratios
are listed for Fy = 345 MPa.

***********************************************************
1. For members having axial compression only
***************************************************************
a) Select members having ratio h/w less than 32.
b) For these sections class for the web will not vary with the
increase in axial load. Also, ratio Cf / phi*Cy = 1.0, ensures that
the sections will be used effectively.
c) Never use sections having b/t ratio greater than 10.76 ( as per
Clause no. 11.2).

***********************************************************
2. For members having bending about strong axis
************************************************************
a) Select members having ratio h/w greater than 40.
b) As relative depth of web is higher as compared to the sections
having h/w ratio less than 32, moment capacity about strong axis will
be higher. Ratio Cf / phi*Cy for these sections will be less than 1.0.
c) Never use sections having b/t ratio greater than 9.15 (Clause no. 11.2 ).

***********************************************************
3. For members having axial compression + bending
************************************************************
a) Select members having ratio h/w ratio less than 32 or between 32 &
40, depending upon the amount of axial load and moment in both the
directions.

I hope this helps.

Regards,

Bhavin Shah








On 2/5/06, Paul Ransom <ad026(--nospam--at)hwcn.org> wrote:
> > From: Ritesh Patel <ritesh758(--nospam--at)yahoo.co.in>
>
> > 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.
>
> Regards
> Paul
>
> --
> R. Paul Ransom, P. Eng.
> Civil/Structural/Project/International
> Burlington, Ontario, Canada
> <mailto:ado26(--nospam--at)hwcn.org> <http://www.hwcn.org/~ad026/civil.html>
>
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