PSI - Issue 44

Manuel Capogna et al. / Procedia Structural Integrity 44 (2023) 705–712 Manuel Capogna et al./ Structural Integrity Procedia 00 (2022) 000–000

711

7

To this end, the class identified according to the other parameters increases, in the event that the bridge falls within the works considered to be of strategic interest for emergencies following a seismic event (with reference to the Limit Emergency Conditions) or, in other words , if it falls into use classes III or IV. These works are expressly indicated by the civil protection or by the competent administrative body. 3.5. Calculation of Seismic Attention Class Once the hazard, vulnerability and seismic exposure classes of the bridge are known, the software proceed with the determination of the Seismic Attention Class, combining them in a similar way to what is done for the determination of the structural and foundational attention class. Combining the class of hazard, vulnerability and exposure of the bridge. A total of 53 combinations is considered, in order to evaluate all possible situations. The actual number of combinations, however, is reduced taking into account that the three factors do not have the same weight in the definition of the AC.

Hazard H

Hazard

Exposure

Hazard

Exposure

Exposure

M-H

M

H M-H M M-L L

H M-H M M-L L

H M-H M M-L L

H

H

H

H M-H H

H M-H

H M-H

M

H

M-H

M-H

M-H

M

M M-L L

M H M-L M-H L M-H

M-H

M

M-H

M

M

M M-H

M

M-L

M-L L

M M M-L

M

M-L

L

M M-L

M

L

M-L

Vulnerability

Vulnerability

Vulnerability

Hazard

Exposure

Hazard L

Exposure

M-L

H M-H M M-L L

H M-H M M-L L

H

H

H M-H

H M-H M-H

M-L

M-H

M

M

M M-L

M

M M-H

M

M-L L

M-L

L

M-L

M-L

M M-L M-L

M

L

L

M-L

L

L M

L

Vulnerability

Vulnerability

Fig. 6. Seismic attention class combination tables used in the model

Greater importance is given to the vulnerability class of the bridge: if it is high, the AC is high whatever the hazard and exposure classes are. In this way, since the vulnerability class is closely related to the level of defectiveness, a bridge with a worrying conservation status always has AC and therefore a high priority.

4 Determination of Seismical Attention Class

Peak ground acceleration

Topographic Category

Soil Category

g

0,05

t4

CDE

Seismical Hazard AC

M-H

Bridge material

Single or multiple spans

Design criteria

Reinforced Concrete

Single

Seismical

Seismical Vulnerability AC

M-L

Structural scheme

Bridge lenght

Defect level Medium-High

Isostatic

High

Medium span lenght

Average Veicles/Day

Road alternatives

m

34

10000

Yes

Seismical Vulnerability AC M-H

Administration crossed

Strategic nature of the bridge

High

Strategic

Seismical Attention Class M

Fig. 7. Determination of Seismic Attention Class.