2. Analysis methods for ISS under earthquake conditions

2.1 Global or direct approach

In the direct method, also known as the "global method", the complete system is analyzed in a single step, which includes :

• the non-linear behavior of the structure or soil (anelastic behavior) ;

• any heterogeneity present in the latter;

• foundation slippage and detachment.

It also makes it possible to deal with contact conditions on the ISS and, implicitly, the effects of radiation and energy dissipation in the infinite part of the unbounded ground.

Direct approaches involve directly solving the dynamics equation governing the behavior of the system (soil, foundation, structure). The...