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Will the method to find horizontal stiffness of an isloator for an SDOF system ie. T=2*pi*sqrt(m/k) give nearby results in SAP for a 3D bridge model?

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asked by about SAP2000
edited by


  • Isolation Time Period T= 2 sec
  • Bridge is horizontally curved 3 spans box girder 88 m length
  • 8 isolators - 2 under each pier and 2 at each abutment

And will the results be nearby if I use area, spline or solid model?

1 Answer

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answered by (329k points)

Creating a building seismic profile requires in most of the times a SDoF model. For a bridge, it's necessary to have 6 DoF comprise of:

  • 3 x translations
  • 3 x rotations in 3D

If you don't have that many directions, the longitudinal axis should be used therefore the calculation you've posted above should match your needs

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