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RE: Afterthoughts : Re: STAAD-Concrete sectional properties

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SAFE, which does analysis/design of R/C slabs (elevated, mats) w/ or w/out
beams, DOES automatically account for cracking in slab & beam elements for
the computation of deflections.  At this time, though, it will only
calculate Ieff based on the required steel content as calculated by the
program itself - you cannot override these values with the actual steel
content.

SAFE is produced by CSI out of Berkeley - it's a good program that our
office has used frequently over the years.

I don't know off-hand of any 3D frame/shear wall analysis programs that do
cracked sections, though.



T. Eric Gillham PE
-----Original Message-----
From: Pankaj Gupta [mailto:soldetail(--nospam--at)hotmail.com]
Sent: Friday, October 12, 2001 4:51 AM
To: seaint(--nospam--at)seaint.org
Subject: Afterthoughts : Re: STAAD-Concrete sectional properties


Dear John,

Just had some afterthoughts in progression to your questions. As previously
stated, they are more related to the software & modelling than the codal
requirements

1) Be very careful of the modeling of the shearwalls, as that can result in
results that are way "off the mark".(This precaution is specially necessary,
when dealing with circumstances that assume that a software does things
"automatically". I had an experience in a peer review of a design in which
the design of a RCC element by the software was "automatically assumed" to
take into account very large axial forces in primarily flexural members. The
software "did", but only after telling it to do so, not by default. ....the
downside of technology.....)

2) This is a question. Is there any software available which does this
"third degree analysis", i.e for example, taking into account the cracking
of concrete? And if there is, then what is the hardware requirement to run
such a software?

Regards

Pankaj Gupta
Structures Online
India


>From: "John Holliday" <john.holliday(--nospam--at)chemtex.com>
>Reply-To: seaint(--nospam--at)seaint.org
>To: <seaint(--nospam--at)seaint.org>
>Subject: STAAD-Concrete sectional properties
>Date: Thu, 11 Oct 2001 23:09:12 -0400
>
>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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