3D dynamic analysis is not... dynamic

[cvdr888]

Hello I am trying to model 3D bricks of elastic soil subjected to acceleration from a record (Loma Prieta, for example). All flowing during the first interval. In the second interval, the analysis is carried out, but it seems that somehow the load was not applied to the elements. Can you please verify my model (attachement)? Thank you in advance, CR. MyModel02.gid.zip

[vpapanik]

You shouldn't apply 'point ground motion from record' when using uniform excitation. Uniform excitation applies acceleration automatically on all restrained nodes on the specified direction (e.g. x-x). https://opensees.berkeley.edu/wiki/index.php/Uniform_Excitation_Pattern

[vpapanik]

Hello, I am attaching a fixed model. Changes:

MyModel02_VKP.gid.zip

• changed solver to UmfPack
• fixed boundary conditions at corners (check KNOWN ISSUES)

OpenSees does not combine constraints (multiple 'fix' commands on the same node). As a result:

    Intersection joints that belong to two lines with different constraints should be handled separately.
    Intersection lines that belong to two surfaces with different constraints should be handled separately.

----> Check again if everything's ok at node level, on meshed model

• fixed boundary conditions on bottom on interval 2 (fix x axis, where record is applied)
• changed time step to 0.01 sec instead of 0.1 sec

most importantly

• added mass density to materials, without a mass matrix, the dynamic analysis won' work.

[cvdr888]

Thank you!!