Introduction to the analysis

To perform a two-dimensional local seismic response analysis by means of the finite element software RSL III 2D, the following steps must be carried out:

1. Definition of the materials and of the geotechnical properties, from Material archive.

2. Generation of the geometric model and subsequent definition of the triangular calculation mesh (button Unstructured mesh generation). As a guiding criterion for the geometric modelling, each soil layer must be schematised by means of a closed polygon to which one of the previously created materials is assigned.

3. Definition of the calculation phases, through the dedicated command. To perform a local seismic response analysis with RSL III 2D, two phases must be defined. In the first phase the initial stress state of the defined model is computed. The second phase consists of the actual analysis of the local seismic response of the model considered, in which, following the assigned accelerograms, the response spectrum is computed.

4. Definition of the boundary conditions. The boundary conditions must be assigned differently for the two calculation phases. In the first phase, the boundary conditions of a classic finite element analysis are assigned, such as hinges on the lower edge and rollers with axis perpendicular to the edge along the lateral surfaces. In the second phase, these constraints must be supplemented by absorbing boundaries, which have the function of limiting the effects of the reflection of the seismic waves at the edges of the model, reflections that have only a numerical character but that in reality do not occur on site.

5. Assignment of the accelerograms. In the second calculation phase, the accelerograms must be assigned in order to perform the local seismic response analysis. In RSL III 2D, the accelerations are assigned along the lower edge of the model, as described in the dedicated section.

6. Local seismic response analysis and visualisation of the results.