Robust and efficient non-linear SSI with Code_Aster and Miss3D

8 October 2012

by A. Nieto-Ferro, G. Devesa et N. Greffet, EDF R&D / AMA

The chaining of Code_Aster and MISS3D, which requires the use of the command CALC_MISS), relies on a BEM-FEM coupling approach. It allows to take into account soil-structure interaction (SSI) in dynamic calculations for seismic analysis. However, this approach is based on a frequency domain resolution and therefore, only linear problems can be solved so far.

The new hybrid Laplace-time domain approach (HLTA), which is also available within the command CALC_MISS and which also uses the soil impedance computed with MISS3D in the frequency domain, allows to perform nonlinear transient calculations with DYNA_NON_LINE. This research work, carried out in the framework of a PhD, has been supervised by the Ecole Centrale Paris, EDF R&D and LaMSID.

In addition to the new test case MISS03, the HLTA has been validated on an industrial-type case, based on the SMART benchmark (asymmetric model of reinforced concrete building, ¼ scale, which was tested on the vibrating table AZALEE at CEA Saclay).

Picture of the SMART model

In the thin shell FEM numerical model, nonlinearities are due to both damaging behaviour of concrete and plasticity of steels. A linear stratified soil with realistic properties is considered. Then, the solution obtained with the HLTA is compared to a full-FEM solution where the soil domain is meshed until bedrock (in our case 130 m depth). Two different positions of the FEM-BEM interface have been tested, one on the free-surface and the other, embedded into the ground (this case would correspond to the inclusion of nonlinearities in a bounded area located under the floor).

Assuming the full-FEM solution as the reference, encouraging results on response spectra (SRO) and on damage assessment at the end of the considered seismic loading are obtained.

Ultimate damage with the HLTA for a surface BEM-FEM interface

[1] A. Nieto Ferro, D. Clouteau, N. Greffet, G. Devésa, On a Hybrid Laplace-Time Domain Approach to Dynamic Interaction Problems. European Journal of Computational Mechanics, 2012.