The OpenSees Community

Thank you, the description has made the process clear.

mlw

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...

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

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...

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...

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...

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

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...

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 ...

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 ...

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...

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...

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...

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

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...