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

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percentage of the collapsed portion of r/c buildings in the complete damage state defined within the procedure FEMA HAZUS (2003). Within the scenario, the possibility of local building collapse, involving relevant consequences for the occupants, exists. Scenario L3 - "Extreme Damage". 50% of the structural elements of the structure attain the collapse damage state D4 (ST) or the damaged elements configure a collapse mechanism (i.e. soft of weak story mechanism). The scenario outlines an ultimate performance status of the construction characterized by the actual collapse of large portions with very serious consequences for the occupants. 7. Evaluation of the consequences for a global damage conditions The total economic consequences for one scenario are evaluated as the sum of the direct and indirect cost related to the damage framework at the considered scenario C EG = C DIR + C IND (3) where C DIR is the sum of the direct costs, C IND is the sum of the indirect costs. The evaluation modalities of both direct and indirect costs are shown in the following. The total economic consequences in terms of direct costs for a generic damage scenario is evaluated as C DIR = (C DS + C DN + C DC ) · η (4) The correction factor η considers the incidence of works and fees required for the retrofitting of the construction and accounts for the costs related to provisional securing, clearance and disposal of resulting materials, excavations, clean-up, urbanization fees, charges for construction works, technical expenses, investigations on soil and materials, increment in seismic capacity. It also accounts for the discount on the retrofitting costs that can be expressed as a function of the damage (and works) extension. Whit this aim a parameter F d that estimates the ratio of damage (and works) extension has been defined as F d = N c,D / N c,tot (5) where N c,D is the number of damaged columns, that is of columns attaining a damage state D2 (ST) or higher, N c,tot is the total number of columns in the building. Fig 2a shows the curve of the reduction (discount) coefficient to be applied to the costs as a function of damage extension. Fig 2b shows the diagrams of the nominal values of the parameter η (dashed line) and the reduced value accounting for damage extension (solid line): the curves derive from the analysis of the actual prices of the retrofitting works concerning the reconstruction after the 2009 L'Aquila Earthquake, Di Ludovico M. et al.(2016).

0,60 0,70 0,80 0,90 1,00 0,00 0,20 0,40 0,60 0,80 1,00 Discount Coefficient F d

1,00 1,20 1,40 1,60 1,80 2,00 2,20

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η

F d

Fig 2 (a) Reduction coefficient of cost of retrofitting works vs. rate of damage extension; (b) correction factor η of direct costs vs. rate of damage extension: nominal values (dashed line), discounted values (continuous line).