Search found 49 matches

by mlw
Fri Sep 21, 2012 3:33 pm
Forum: OpenSees.exe Users
Topic: Details of the uniformExcitation pattern
Replies: 4
Views: 1160

Re: Details of the uniformExcitation pattern

Thank you, the description has made the process clear.

mlw
by mlw
Tue Sep 18, 2012 1:32 pm
Forum: OpenSees.exe Users
Topic: Details of the uniformExcitation pattern
Replies: 4
Views: 1160

Re: Details of the uniformExcitation pattern

Vesna, Thank you for your reply. Could you please clarify my understanding of the computer code presented on the link which you provided: 1) At time step=0 the velocity of all nodes is set to zero 2) The velocity at time step=1 is calculated from the uniformExcitation pattern acceleration at time st...
by mlw
Mon Sep 17, 2012 5:15 pm
Forum: OpenSees.exe Users
Topic: Details of the uniformExcitation pattern
Replies: 4
Views: 1160

Details of the uniformExcitation pattern

Hi everyone,

I have been using the uniformExcitation pattern to simulate dynamic loading and notice that it allows for acceleration amplification/attenuation through the the soil/structure.
Where can I find more details as to how the uniformExcitation pattern is implemented in OpenSees?

Thanks

mlw
by mlw
Mon Aug 06, 2012 6:54 pm
Forum: OpenSees.exe Users
Topic: Rayleigh damping implementation
Replies: 1
Views: 774

Rayleigh damping implementation

Hi all, Can anyone please tell me if the Rayleigh damping parameters are updated during an OpenSees analysis. The Rayleigh damping mass and stiffness matrices are calculated based on the mass and stiffness of a model at the start of an analysis. But if large strains occur (such as during the loading...
by mlw
Thu Jun 14, 2012 12:23 pm
Forum: Soil Modelling
Topic: pressureDependMultiYield relation to Yang, Elgamal and Parra
Replies: 1
Views: 1218

pressureDependMultiYield relation to Yang, Elgamal and Parra

Hi all, Could anyone please tell me how the pressureDependMultiYield input parameters (i.e. contrac, dilat1 and 2, and liquefac1, 2, and 3) relate to the equations presented in Yang, Elgamal and Parra (2003) "Computational model for cyclic mobility and associated shear deformation" For example: is d...
by mlw
Mon Jun 11, 2012 3:01 pm
Forum: Soil Modelling
Topic: Pipe pile response in soil
Replies: 0
Views: 850

Pipe pile response in soil

Hi all, I have been comparing the OpenSees pile bending moments against case history data for seismic shaking table and centrifuge experiments. I have compared 4 case histories. What I am finding is that OpenSees seems to underpredict pile bending moments of the thin walled pipe piles, but has no pr...
by mlw
Mon Jun 11, 2012 2:58 pm
Forum: OpenSees.exe Users
Topic: Bending moments of pipe piles
Replies: 1
Views: 770

Re: Bending moments of pipe piles

Could someone please help me out here?
I have also been talking to another postgrad student who is working with OpenSees and he is having the same problem

mlw
by mlw
Sun Jun 03, 2012 4:36 pm
Forum: OpenSees.exe Users
Topic: Bending moments of pipe piles
Replies: 1
Views: 770

Bending moments of pipe piles

Hi all, I have been comparing the OpenSees pile bending moments against case history data for seismic shaking table and centrifuge experiments. I have compared 4 case histories. What I am finding is that OpenSees seems to underpredict pile bending moments of the thin walled pipe piles, but has no pr...
by mlw
Thu Mar 15, 2012 5:33 pm
Forum: OpenSees.exe Users
Topic: Shear deformation only
Replies: 0
Views: 590

Shear deformation only

Hi all, For my research I need to assess the difference in behaviour of a model deforming with a combination of shear and flexural deformation, and a model deforming with shear deformation only. Is there any way that I can specify the elasticBeamColumn material to deform only in shear? Perhaps if I ...
by mlw
Thu Mar 01, 2012 8:04 pm
Forum: Soil Modelling
Topic: Pore pressure as calculated by pressureDependMultiYield
Replies: 0
Views: 1763

Pore pressure as calculated by pressureDependMultiYield

Hi all, I have been working on verifying the OpenSees materal (pressureDependMultiYield) against time histories of shear strain and excess pore pressure ratio of experimental data. So far I have examined 2 shaking table experiments (one dry and the other saturated and liquefiable), and a centrifuge ...
by mlw
Tue Nov 15, 2011 1:26 pm
Forum: Soil Modelling
Topic: Modelling along the line of symmetry
Replies: 1
Views: 1430

Modelling along the line of symmetry

Hi all, I am modelling a pile (elasticBeamColumn) in liquefiable sand. Only half the model is analysed along the line of symmetry. Acceleration is applied through the uniformExcitation pattern parallel to the line of symmetry. I now have tried to simulate 3 case histories of shaking tables/centrifug...
by mlw
Tue Nov 15, 2011 1:03 pm
Forum: OpenSees.exe Users
Topic: Relative or absolute displacements
Replies: 3
Views: 2314

Re: Relative or absolute displacements

Thanks vesna, I will include the time series tag to get absolute displacements. But the problem is stil not solved. I now have tried to simulate 3 case histories of shaking tables/centrifuges and the results from all three are the same. Displacement is half of the experimental value, and because dis...
by mlw
Mon Nov 14, 2011 12:09 pm
Forum: OpenSees.exe Users
Topic: Relative or absolute displacements
Replies: 3
Views: 2314

Relative or absolute displacements

Hi all, I am recording displacements in X, Y, and Z directions using the following commands: eval "recorder Node -file soilDispX.out -time -node $nodeList -dof 1 disp" eval "recorder Node -file soilDispY.out -time -node $nodeList -dof 2 disp" eval "recorder Node -file soilDispZ.out -time -node $node...
by mlw
Mon Oct 24, 2011 11:21 am
Forum: OpenSees.exe Users
Topic: Acceleration as recorded by the uniformExcitation pattern
Replies: 3
Views: 969

Re: Acceleration as recorded by the uniformExcitation patter

So can I just clarify. Say if I have an input motion with a max acceleration of 0.3g, then this 0.3g would still be applied to the nodes at the base of the model even though the recorder is not recording it?

Thank you for your time

mlw
by mlw
Sun Oct 23, 2011 7:29 pm
Forum: OpenSees.exe Users
Topic: Acceleration as recorded by the uniformExcitation pattern
Replies: 3
Views: 969

Acceleration as recorded by the uniformExcitation pattern

Hi all, I have a query about the uniformExcitation pattern. I am modelling a pile surrounded by soil and running a dynamic analysis with the uniformExcitation pattern. The command is implemented by the following: pattern UniformExcitation 1 1 -accel "Series -fileTime acc_time.dat -filePath acc_value...