PSI - Issue 44

R. Siano et al. / Procedia Structural Integrity 44 (2023) 1038–1044 R. Siano, A. Fatnassi, F. V. De Maio, P. Basso, M. Cademartori / Structural Integrity Procedia 00 (2022) 000–000

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definition of the retrofit scenarios was performed with respect to the minimum safety required provided by the NTC2018 the Life Safety (SLV) and the Immediate Occupancy (SLD) limit state. The improvement of both static and dynamic behaviour of the studied buildings was pursued having as specific goal the fulfilment of the performance requirements provided by the national seismic code. At the same time functional and economical requirements were also accounted for in the definition and testing of each seismic retrofit scenario, such as the cost associated to the retrofit interventions, the interruption or limitation of the buildings use during works and the interference with installations and functional aspects. The analysis of retrofit scenarios involved both traditional and innovative strategies, comparing the efficiency of scattered interventions (reinforced concrete jacketing), based on the improvement of the specific resisting capacity of all structural components, in comparison with dissipative and non-dissipative solutions (Buckling-Restrained Axial Dampers, steel bracings or r.c. shear walls), aimed at replacing or unloading the existing structural systems. The efficiency of each retrofit scenario was then defined by evaluating the reduction of seismic vulnerability achieved, the associated cost and the functional impact measured in terms of constructability and service disruption. The stability of non-structural components was also investigated both by limiting the structures displacements in dynamic conditions and providing specific interventions aimed at improving the degree of connections to structural components. Table 1 reports the minimum risk indexes obtained for each building with reference to their existing configurations and in the retrofitted ones with respect to LS performance level.

Table 1. Minimum risk indexes for the whole building sample defined for LS in the retrofitted configuration.

Retrofit Scenario

RI LS Retrofit Configuration

Building

Building Group

RI LS Existing Situation

1.04 1.04

Building 1 Building 2 Building 3 Building 4 Building 5 Building 6 Building 7 Building 8 Building 9 Building 10 Building 11 Building 12 Building 13 Building 14 Building 15 Building 16 Building 17 Building 18

2 2 2 2 3 2 1 1 3 3 2 2 4 4 4 2 2 2

0.11 0.11 0.11 0.11 0.06 0.10 0.11 0.14 0.08 0.33 0.10 0.10 0.04 0.04 0.12 0.66 0.38 0.26

Buckling-Restrained Axial Dampers Buckling-Restrained Axial Dampers

Steel bracings and RC shear walls for each direction 1.01 Steel bracings and RC shear walls for each direction 1.01 Steel bracings and RC shear walls for each direction 1.01

RC shear walls and Columns concrete jacketing RC shear walls and Columns concrete jacketing RC shear walls and Columns concrete jacketing RC shear walls and Columns concrete jacketing RC shear walls and Columns concrete jacketing

1.01 1.03 1.04 1.08 1.01 1.01 1.01 1.04 1.04 1.00 1.00 1.00 1.03

Seismic isolation Seismic isolation Seismic isolation Seismic isolation Seismic isolation

Columns concrete jacketing Columns concrete jacketing Columns concrete jacketing