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Re: software for nonlinear static push-over analysis

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Hi Peter,

Last May, there was a discussion on pushover analysis within this list.
Unfortunately you cannot find these postings in the SEAOC mail archive.
(The mails between March and June are missing?! )

I went through my own archive and copied for you the relevant postings.

Best regards,
Peter Rangelow

PS. I shall excuse to those authors whose names are missing
in the cited mails - it is just because their postings were unsigned
and I had no time to extract their names from the mail headers.

Dr. Peter Rangelow
Hochtief AG, Abt. IKS
Bockenheimer Landstr. 24
60323 Frankfurt

Phone:	+(49-69) 7117-2539
Fax:	+(49-69) 7117-2782
Email:	rangelow.peter(--nospam--at)

>Von: Kaspar Peter
>An: seaoc(--nospam--at)
>Betreff: software for nonlinear static push-over analysis
>Datum: Mittwoch, 3. September 1997 16:35
>I'll do for seismic evaluation of existing buildings nonlinear static
>push-over analyses. And I'm looking for the appropriate tool to do this
>analyses. The software I've already heard of is IDARC, DRAIN-2D, and all
>the multi-purpose, high-power programms like ANSYS, ABAQUS, others....
>Please, if anybody has conducted on his own a push-over analysis or thinks
>he knows any tool I can use.
>Thanks a lot, Kaspar
>Kaspar PETER
>Federal Institute of Technology Lausanne
>EPFL Ecublens
>CH - 1015 Lausanne
>Tel. ++41 21 693 2870
>Fax. ++41 21 693 5884
>email kaspar.peter(--nospam--at)

============================ May, 1997 emails from the SEAOC list
>From: 	Kalyan Vaidyanathan[SMTP:KVaidyanathan(--nospam--at)]
>Sent: 	Tuesday, May 20, 1997 7:21 PM
>To: 	seaoc(--nospam--at)
>Subject: 	Software for Pushover Analysis
>I am a structural engineer working in a
>consulting company here in Boston.  I am
>interested in software that can be used to do
>non-linear pushover analysis and am looking for
>recommendations.  I am told there is one
>software called "sc-push" (did I get that right?)
>available.  Is that good?  Anybody got any
>experiences?  Other software?
>-Kalyan Vaidyanathan
In a recent seminar on pushover analysis, Ronald Hamburger mentioned
Drain 2D-X, ANSYS, Non-SAP, ABACUS, and NASTRAN.  Suggest you contact
him at EQE International (E-mail ROH(--nospam--at) for further details (or
maybe he will see your post and respond in person).
SC-Push is available from SC Solutions at 408-486-6060. Their web site
is I've heard good things about SC-Push.

Bruce Bates
RISA Technologies
ANSYS, ABACUS & NASTRAN are Finite Element Software more suited for
mechanical structural problems.  But the analysis of plates & shells can
very well be accomplished using these software.  I am not sure that
there was a
static pushover analysis option (atleast in ANSYS, which I had used in
school way
back in 1994-things may have changed since then).

DRAIN 2D : I might be wrong, but the educational version that I have has
nonlinear analysis (modeling plasticity) but doesn't have static
pushover analysis.

Non-SAP 2000 : Again I have the educational version of NonLinear SAP
and there is no mention of this feature being available. In fact, in the
seminar held at San Diego, Dr. Habibullah actually said that this was
the next problem they
were working on and from what I understood, they were planning to
include this
in their future versions.

Please do not hesitate to correct me if I am wrong.
 -Swaminathan Krishnan
DRAIN-2DX can perform pushover analyses quite easily.  However, the
user's manual is not the greatest, but once you figure it out it's a
great program.  As the name implies, the program only performs
2-dimensional analyses.  DRAIN-3D may also have the same capabilities
for 3-dimensional structures, but I have not personally used it.
ANSYS  and ABACUS are full blown FEM programs, so the learning curve
is pretty steep if you're not familiar with how they work.  Computer
Structures Inc. (CSI) is in the process of developing a program, or

incorporating it into SAP 2000 or ETABS, to perform pushover
analyses.  Dr. Graham Powell, who developed DRAIN at Berkeley,
joined CSI most probably with the intent of developing a pushover
analysis program and perhaps streamlining some of the nonlinear
analysis in their current programs.  Finally, there is your standard
linear elastic analysis program.  There's nothing too special
required to perform pushover analyses except an account to keep track
of the externally applied loads, internal member forces, and

David Gwie

kpff Consulting Engineers, Inc.

I've  done structural work for a long time, but I can not figure out
"pushover analysis" is to save my soul. I've been studying the messages
this thread, but I just can't get.  Maybe I am the only one here who
know what this is all about. What is PUSHOVER?


Several programs are available for "pushover" or static nonlinear
analysis.  Commercially available packages include ABAQUS, ANSYS,

and FACTS.  Public domain programs include DRAIN-2DX, DRAIN-3DX,
and IDARC.  Public domain programs are inexpensive, have no technical
support and generally lack pre and post processors. DRAIN-2DX is
with a commercial post-processing package DRAIN-PRO (ASC 303-278-6234).

my experience, DRAIN-2DX is good package for most structural engineering

I don't have any experience with SC-PUSH.  You might want to contact SC
Solutions (408-486-6060).

Also, CSI (510-845-8177)is expected to introduce "NL-PUSH" some time
year. This should be very good program for structural engineering

Humayun Abbas
SOHA Engineers

 I've  done structural work for a long time, but I can not figure out
 "pushover analysis" is to save my soul. I've been studying the messages
 this thread, but I just can't get.  Maybe I am the only one here who
 know what this is all about. What is PUSHOVER?

NO, you are not the only one!!!!!!!
Pushover Analysis is a static nonlinear analysis of a structure wherein
aim is to analyze the model of a structure until failure. As we keep
increasing the
static load on a structure various weak-points & weak-links in the
structure start
yielding and the structural stiffness & damping (since currently we are
looking at
"static" pushover, this may not affect the analysis) keep getting
modified, until
the formation of a mechanism leading to collapse.  This type of an
analysis would be a
good design procedure as the designer physically gets to see the various
of yielding, plastic deformation & finally the collapse mechanism.
Using a
good judgement on the choice of applied sequential loading (2 or 3 or
more cases
as needed), the engineer should be able to appropriately tune the
with respect to ductility requirements, key member strength & stiffness
etc. IMHO, it is a good design tool, but when it comes to "dynamic"
analysis, there are going to be lots of problems, as the whole analysis
is very
sensitive to damping ratio (which dynamic analysis isn't) and since the
current viscous
damping assumption has widely-varying magnitude assumptions, the
analysis may give
mediocre to bad results as far as the dynamic behaviour of the building
concerned. There is a lot of research work being done on this subject
and I am sure
this will be the next big step in our goal to design better structures.

In this context, I should mention that obviously any general purpose
Element Program (ANSYS, ABACUS etc.) should be able to do Pushover
Analysis, simply
because of its very definition. But the point is, currently other than
"SC-Push", I don't
know of any other "building analysis" program that is specially geared
do this kind of a systematic analysis wherein a lot of book-keeping is
involved and
the engineer should be very careful in analyzing the analysis results.

As usual, comments are more than welcome.

 -Swaminathan Krishnan
If you seek a program suitable for 3-dimensional pushover analysis of
building structure, I recommend you CANNY-E program.
As I know, the general purpose nonlinear programs such as ANSYS, ABAQUS,
NASTRAN are not easy to use in building anlaysis.
I have used IDARC2D Program (Developed at SUNY at Buffalo) for Nonlinear
Pushover Anlyses. The program is capable of analyzing building
in the inelastic range subjected to combined horizontal and vertical
excitations, quai-static cyclic loading and incrementally applied static
loads. The program can include P-delta effects and is capable of
generating trilinear moment curcature properties by either using
nonsymmetric trilinear envelope models or just cross section data.
I have to say that it is not a user-friendly program, it gives good idea
of the behaviour of the structure under nonlinear static and dynamic
loads and crack/yield propagation through the building. I would like to
know if someone has used the new versions.

Gurbuz Aydemir			
System Development Specialist
STFA Construction Co.		Phone : (+90.216) 3266868/int.676
81190  Altunizade      \|/	Fax   : (+90.216) 3395579,3255798
Istanbul, Turkey       @ @	mailto:gaydemir(--nospam--at)
Swaminathan Krishnan, Thanks for the explanation.

Pushover Analysis sounds like it is in a pretty experimental stage. Is
already being used in design of actual buildings? If so, at what scale
complexity (i.e. size and height)?
Pushover analyses is not really in an experimental stage.  We use
analyses quite routinely for seismic evaluation and retrofit of bridges.
buildings, pushover analysis is being used more and more frequently for
evaluation of the existing structure and for the verification of
design.  As FEMA 273 kicks in, probably some time in 1998, NL pushover
analyses is expected to become a commonly used procedure for seismic
evaluation of existing buildings. Nonlinear time history analyses are

common for base isolated structures and/or structures with energy
dissipation devices.  The analyses that have been performed for the

evaluation of San Francisco Bay bridges have included both static and
dynamic nonlinear analyses,  considering material and geometric
nonlinearities and even multiple support excitation.  Before the Loma
earthquake, we would expect studies like that only in research.

Humayun Abbas
SOHA Engineers, San Francisco
It is currently being used for the analysis of existing buildings for
seismic retrofit projects.  It is useful in determining what elements
need to be strengthened.  It is a key analysis tool for performance
seismic design.  It won't answer all the questions about how a building
will perform but it can be a good start.

It is most useful for buildings in the 3 to 8 story size.  If there are
significant torsional problems and /or vertical irregularities then a
pushover analysis may not provide reliable results.

It is also being used for the design of new buildings (less frequently).
Here again it is tied to performance based design so you would be
for a better understanding of how the building would perform during an
I do not know of any company that is currently using this analysis
procedure actively.
I do not foresee this happening in the next 2-3 years, atleast not until
the more popular analysis packages incorporate this. As I pointed out
earlier, it is
indeed in a very preliminary stage.  The people at CSi (Dr. Graham
Powell, in
particular) are very big proponents of this methodology. In fact, some
articles by Dr. Powell in
"The Source" have reference to this procedure, in regards to its
applicability and
 -Swaminathan Krishnan