Seismic accelerations (es-ES)

Seismic accelerations are induced to the structure by the seismic ground vibration. The seismic response of a structure i.e. its accelerations, induce deformations and stresses.

The structural seismic response depends on the following factors: the Seismic Zone the building belongs to, the Importance Factor, the Ground Type, the Viscous Damping, the Behaviour Factor  and of course on the magnitude and the distribution of the EI stiffnesses and masses of the building.

Hereafter the seismic response factors of buildings are considered.

Map of local hazard seismic zones of Greece

The seismic ground vibration is described by the acceleration a_gR which denotes the reference peak ground acceleration on type A ground.

Each earthquake prone country is divided into Zones depending on the local hazard. A specific reference acceleration a_gR corresponds to each zone.

For instance, Greece is divided into three zones: Zone 1: a_gR=0.16g , Zone 2: a_gR=0.24g, Zone 3: a_gR=0.36g, where g is the gravity acceleration.

 

Class	γI	Buildings of minor importance for public safety, e.g. agricultural buildings, etc.
I	0.8	Ordinary buildings, not belonging in the other categories.
II	1.0	Buildings whose seismic resistance is of importance, in view of the consequences associated with a collapse, e.g. schools, assembly halls, etc.
III	1.2	Buildings whose integrity during earthquakes is of vital importance for civil protection, e.g. hospitals, fire stations, power plants, etc.
IV	1.4	Buildings of minor importance for public safety, e.g. agricultural buildings, etc.

 Buildings are classified in four importance classes, depending on the consequences of collapse. Each importance class has an importance factor γ_I usually varying between 0.80 and 1.40.
The design acceleration a_g on type A ground derives from the reference acceleration multiplied by the importance factor, i.e. a_g =γ_I×a_gR.