Search found 64 matches

by nitadorakis
Mon Dec 03, 2012 10:49 pm
Forum: OpenSees.exe Users
Topic: About dynamic analysis
Replies: 12
Views: 1804

Re: About dynamic analysis

Thanks.
This will save a lot of computational time.
by nitadorakis
Mon Dec 03, 2012 12:30 pm
Forum: OpenSees.exe Users
Topic: About dynamic analysis
Replies: 12
Views: 1804

Re: About dynamic analysis

Thanks for your reply.
Indeed, I use that element, and I would be gratefull if this modification-addition could be done.
by nitadorakis
Sun Dec 02, 2012 1:02 am
Forum: OpenSees.exe Users
Topic: About dynamic analysis
Replies: 12
Views: 1804

Re: About dynamic analysis

Hi, Regarding the DATABASE command, I noticed that it doesn't seem not to work with TripleFrictionPendulum elements. Is there any alternative way to restore a model in the state just after static analysis when doing IDA and want to exclude the static analysis part from the IDA loop? When using the R...
by nitadorakis
Wed Feb 22, 2012 2:37 am
Forum: Soil Modelling
Topic: Rayleigh damping in soil
Replies: 7
Views: 8444

Re: Rayleigh damping in soil

In all the examples at http://cyclic.ucsd.edu/opensees/ the mass proportional damping coef. in set to zero. They are about single quadrilateral elements or columns of quadrilateral elements. On the other hand, in geotechnical examples at http://opensees.berkeley.edu/wiki/index.php/Examples, mass pro...
by nitadorakis
Tue Jan 31, 2012 12:47 pm
Forum: OpenSees.exe Users
Topic: Imposed displacement time series ground motion
Replies: 2
Views: 1138

Re: Imposed displacement time series ground motion

Thank you

I was using constraints Penalty 1.0e18 1.0e18.
I tried with Transformation method and it worked fine. The response in now rational.
Could you please give a guideline when one should use the penalty method and when the transformation method?
by nitadorakis
Sun Jan 29, 2012 9:52 am
Forum: OpenSees.exe Users
Topic: Imposed displacement time series ground motion
Replies: 2
Views: 1138

Imposed displacement time series ground motion

Hi I have a problem with a simple model which is not structural but maybe someone could help me here, because in soil-modelling subforum nobody helps me. I try to impose displacement time series at all the base nodes of a rectangular 2D soil layer that is simulated with ElasticIsotropic nDMaterial f...
by nitadorakis
Sat Jan 28, 2012 1:59 am
Forum: Soil Modelling
Topic: Rayleigh damping in soil
Replies: 7
Views: 8444

Rayleigh damping in soil

I've seen in many OpenSees geotechnical examples that mass matrix-proportional coefficient (a) of the Rayleigh damping expression is is taken equal to zero. I was wondering if (a) is rational to be zero in geotechnical problems. Typically, the stiffness proportional coeff. represents the loss of ene...
by nitadorakis
Sat Jan 21, 2012 12:32 pm
Forum: OpenSees.exe Users
Topic: recorder in push analysis
Replies: 13
Views: 3810

Re: recorder in push analysis

Indeed. It was a misunderstanding.
Thank you very much.
by nitadorakis
Sat Jan 21, 2012 12:12 pm
Forum: Soil Modelling
Topic: Response analysis of an elastic soil layer
Replies: 0
Views: 756

Response analysis of an elastic soil layer

Hi It's the first time I'm working on soil-modelling, so I'm encountering a few problems with the analysis. The problem is about a elastic 2D soil layer 980x50m, meshed by 2x2m quad elements, fixed in both directions in its base and right boundary. This layer is being excited by an horizontal sinuso...
by nitadorakis
Thu Jan 12, 2012 12:29 am
Forum: OpenSees.exe Users
Topic: recorder in push analysis
Replies: 13
Views: 3810

Re: recorder in push analysis

Thank you for your reply. Your explanation is clear that Vb=lamda=time when Σ(Fi)=1. I had misunderstood the concept of all load patterns (even static ones) being associated with a time series. However, the thing that still puzzles me is why lambda (=time) can be decreased in displacement-controlled...
by nitadorakis
Mon Jan 09, 2012 8:25 am
Forum: OpenSees.exe Users
Topic: recorder in push analysis
Replies: 13
Views: 3810

Re: recorder in push analysis

vesna wrote: > Yes, it is a force. Dear Vesna, I wish you a happy new year! Just to make a note on your reply, I'm wondering why the time (i.e. the 1st) column of the output file represents the base shear ONLY in the case that the sum of the load vector's component at each elevation is equal to 1 (i...
by nitadorakis
Sun Mar 20, 2011 1:18 am
Forum: OpenSees.exe Users
Topic: Pushover curve's shape
Replies: 7
Views: 1627

Re: Pushover curve's shape

thank you Vesna

I guess you are right.
I was wondering if it is more appropriate to use corotational transformation in pushover analysis instead of PDelta, due to the large displacements.
by nitadorakis
Wed Mar 16, 2011 10:26 am
Forum: OpenSees.exe Users
Topic: Pushover curve's shape
Replies: 7
Views: 1627

Re: Pushover curve's shape

What do you mean that the P-delta might not work well...?
Apart from the Steel01 and the transformation, is there somenthing else I should check, or leave it as it is?
by nitadorakis
Wed Mar 16, 2011 9:21 am
Forum: OpenSees.exe Users
Topic: Pushover curve's shape
Replies: 7
Views: 1627

Re: Pushover curve's shape

Thanks Vesna

I used the expession:
[expr ($fu-$fy)/($eu-$ey)/$fy*$ey] where
fy 500000
fu 600000
ey 0.0025
eu 0.025
So, b= 0.022.
I think it's low.Isn't it?
by nitadorakis
Tue Mar 15, 2011 2:21 pm
Forum: OpenSees.exe Users
Topic: Pushover curve's shape
Replies: 7
Views: 1627

Pushover curve's shape

Hi all. I have a question regarding the pushover curve I'm getting as a result of the static pushover analysis of a 4-strorey plane RC frame. Although PDelta geometric transformation is used for the column elements, the curve is increasing up (could be approximated as a bilinear) to the target displ...