1. Reference problem#

1.1. Geometry#

We use a skewer model of the building with a raft that is modeled by a layer of 136 surface meshes TRIA3 and 6 degrees of freedom are assigned to its underside.

The modeling presented is a simplified model for which the building is represented by a flat structure. Four substructures are represented by four non-heavy vertical beams, of variable flexural inertia and carrying nodal masses and inertias representing civil engineering and equipment. Discreet elastic connections connect these beams at various levels. The four beams are embedded in a general frame with a high flexural inertia.

1.2. Material properties#

\(E\mathrm{=}4.0{10}^{10}\mathit{Pa}\)

\(\rho \mathrm{=}2500\mathit{kg}\mathrm{/}{m}^{3}\) (heavy items only)

\(\nu \mathrm{=}0.15\)

  • characteristics of point masses (”M_ TR_D_N “) and node-node connections (”K_ TR_D_L”).

1.3. Boundary conditions and loads#

Solid connections on the upper and lower sides of the frame (LIAISON_SOLIDE on node groups \(\mathit{HRADIER}\) and \(\mathit{SRADIER}\)).

  • Blocking the central node (\(\mathit{N98}\)) of the lower face (6 degrees of freedom) to calculate rigid body modes,

  • Nodal force of \({10}^{4}\mathit{Newtons}\) applied to node \(\mathit{N1500}\),

  • Or transient acceleration spectrum \(\mathit{EUR}\) in the \(X\) direction with amplitude \(0.25g\),

  • Or unit harmonic acceleration in directions \(X\) and \(Y\)

1.4. Initial conditions#

Zero travel, speed, and acceleration.