Floor class

Description of stratigraphic profile

S describing type 1 spectra S describing type 2 spectra

S describing type 1 spectra S describing type 2 spectra

A

Rock or similar geological formation with a surface layer of up to 5 m of less resistant material

1.0

1.0

B

Steep deposits of over-consolidated sand, gravel or clay, at least several tens of meters thick, characterized by a progressive increase in mechanical properties with depth

1.2

1.35

C

Deep deposits of medium-density sand, gravel or moderately stiff clay, several tens to several hundreds of meters thick.

1.15

1.5

D

Deposits of cohesionless soils of low to medium density (with or without soft cohesive layers) or comprising mostly soft to firm cohesive soils.

1.35

1.8

E

Soil profile comprising a superficial layer of alluvium with vs values of class C or D and a thickness of between approx. 5 m and 20 m, resting on a stiffer material with vs > 800 m/s

1.4

1.6