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Re: STAAD-Concrete sectional properties

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Dear John,

I am not very much familiar with American codes, so I cannot reply to other
questions, but I can answer Q #3.

The answer is that STAAD does not take reduced section properties due to
cracking. P-delta analysis performs a secondary level analysis, in which it
takes into accounts the forces generated by the deflections caused by the
first order analysis, and that is all.

Regards

Pankaj Gupta
Structures Online
India

----- Original Message -----
From: John Holliday <john.holliday(--nospam--at)chemtex.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Friday, October 12, 2001 8:39 AM
Subject: STAAD-Concrete sectional properties


> I am reviewing the STAAD input for a Reinforced Concrete six story
> industrial building and have a few questions that I hope someone can
answer.
> 1.  Is it usual practice to use the member properties in ACI 10.11.1?
>
> 2.  Section R8.6.1 talks about using gross section properties for all
> members in braced frames. My building has two parallel shear walls in the
> east-west direction (in combination with moment resisting frame) and only
a
> moment resisting frame in north-south direction. Can I use gross section
> properties?
>
> 3. STAAD PDelta analysis has been performed. The engineer who done this
> analysis informed me that the PDelta analysis in STAAD takes into account
> (automatically) reduced section properties due to cracking, therefore it
is
> acceptable to input gross section properties. Is this correct?
>
> 4. I reviewed the UCB on this subject. Section 1633.2.4 states that
flexural
> and shear properties shall not exceed one half of the gross section
> properties unless a rational cracked-section analysis is performed. Could
> someone explain to me what a rational cracked-section analysis is.
>
> 5. Section 1910.11.1 of the UCB gives similar member properties as ACI
> 10.11.1 but seems to contradict the requirements of UCB Section 1633.2.4
> i.e. using 50% of gross. Can someone clarify this for me.
>
> Thanks in advance for any help.
>
> John Holliday  P.E.
>
>
>
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