PSI - Issue 44

Alessandro Fulco et al. / Procedia Structural Integrity 44 (2023) 195–202 Alessandro Fulco et al. / Structural Integrity Procedia 00 (2022) 000–000

200

6

Once the direct costs have been evaluated, a Global Loss Index ID = C U,DIR / C U,conv (6) is defined, where C U,DIR = C DIR / A exp is the unit value of the direct costs, being A exp the usable floor area, and C U,conv is the conventional unit cost for demolition and reconstruction of buildings, in the present application it has been derived by the reconstruction costs provided by the Italian government for the buildings damaged in the 2016 Central Italy Earthquake. This cost - estimated for dwelling, or office or school buildings - is equal to 1400 € /sqm. If the consequence evaluation concerns the performance assessment of the building from the point of view of the management of the building itself it is enough to consider the previously evaluated direct costs. With the aim of having a more general vision of the problem that includes the social, administrative, political, ethical, macro-economic aspects, besides the direct costs previously evaluated, also the indirect costs should be taken into account. Indirect costs include costs related to: (a) temporary relocation of residents; (b) downtime for commercial activities; (c) first emergency aids; (d) structures devoted to the reconstruction management. The indirect costs are evaluated with the following expression C IND = T D,eff · A BLDG · c UD (7) where A BLDG is the commercial area of the whole building; c UD represents the rent daily cost per unit of area of a similar building: on the basis of an Italian market research it is included in the range 0.05 - 0.50 € /m 2 depending on

the building type and market conditions, T D,eff is effective downtime (in days). 8. Estimation of the expected consequences in predefined time intervals

The expected annual economic consequences (losses) are calculated by summing the cost C TOT of each scenario multiplied by the annual probability of that consequence, approximately assumed to be equal to the probability to attain or overcome the event causing the scenario. Actually, the most interesting parameter consists of the expected consequences (costs or losses) C EXP (N) in an interval of time N that is significant in the decision making process. It can be computed with the following expression

1 C P P C P - + = é × - + × ê ê å ( ) N ( ) N , EG l , EG L L 1 ( ) L l

ù ú ú û

( ) N

( ) N

( ) N

(8)

C

F

=

×

EXP

A

ë

l

1

where

/ R l N T

( ) N

N

(9) is the probability to reach of to overcome the l -th scenario in N years, being L the number of scenarios; T R,l the return period of the seismic intensity corresponding to the l -th scenario; " ($) is the actualization factor related to the compound interest in next N years. Ordinarily the interval of time for which computing the expected cost (or likely cost) is the conventional reference lifetime of the construction, but it can be a different one according to the objectives of the decision making process. Generally, from the numerical calculations it results that the investment in increasing the seismic capacity of a building becomes more and more cost-effective when the considered interval on which computing the consequences becomes larger and larger. , , 1 1 (1 1 / ) R l l P e T = - @ - -