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RE: STAAD Pro

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> ----------
> From:
> James_F_Fulton(--nospam--at)RohmHaas.Com[SMTP:James_F_Fulton(--nospam--at)RohmHaas.Com]
> Reply To: 	seaint(--nospam--at)seaint.org
> Sent: 	Wednesday, January 27, 1999 11:43 AM
> To: 	seaint(--nospam--at)seaint.org
> Subject: 	RE: STAAD Pro
> 
> Maybe this is a good time to again ask, what alternative programs have
> people 
> 
> 
Most softwares have the same basic and common features with different
degree of user-machine interfaces. What I would like to say is to
compare the new features that may reduce the analysis and design costs,
and provide more accurate data for design. I think the following two
special features (provided in IFAS) may be useful.


(1) Theoretical Analysis of Effective Length Factor

Effective length factors are required to design compression members.
Many books and manuals suggest users to use the alignment charts to
estimate the effective length factors. Users need to determine if braced
or unbraced frames, and need to calculate stiffness ratio of adjacent
members, and then to determine the effective length factor. It takes
time, and never guarantees how accurate it is.

If we look back the history background, those alignment charts were
introduced when structural engineers didn't have a computer to analyze
the effective length factors. Those charts are for estimation.
Presently, almost every structural engineer has a computer. It may be a
time for us to consider theoretical analysis of effective length factor.

Theoretically, every effective length factor must be analyzed in the
whole system, not only on a local member. It is not as simple as the
alignment charts, simply dependent of stiffness ratio. The real
situation is more complex. A support settlement, or spring support, or
inclied support, or other attributes may contribute to the length
factors.

With this feature, it is unnecessary for structural engineers to assume
any length factors and is unnecessary to determine if braced or
unbraced. It can provide more accurate data and reduce the design cost.


(2) Analysis of Connector Stiffness

Speaking of connection design, design codes, i.e., UBC, require
connections to have "sufficient strength for connector loads" and
"adequate rigidity". Most packages can analyze the connector loads. The
problem is on the "adequate rigidity". How much is adequate? Analysis of
the required connector stiffness is certainly necessary to comply with
the codes.