Modelling along the line of symmetry

[mlw]

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/centrifuges and the results from all three are the same. Displacement is half of the experimental value, and because displacement is half soil shear strain and bending moment of my pile are also half. Yet acceleration and excess pore water pressure are correct.

Have you come across this before? Are there any other examples of where the opensees code (particularly displacements & bending moments) has been verified against case histories for a pile in soil with dynamic loading?

Perhaps because only half the model is analysed displacements/shear strain/bending moments should be doubled? A full size model would have twice the inertia and twice the displacements?

Thank you for your time

mlw

[madgobed]

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