PSI - Issue 78

Ciro Del Vecchio et al. / Procedia Structural Integrity 78 (2026) 913–920

915

variability, modelling uncertainties (O’Reilly & Sullivan, 2018) , and uncertainties in material properties (concrete compressive strength) and reinforcement details (amount of column transverse reinforcement). The proposed framework requires the definition of the geometric characteristics of the buildings, the material properties, a set of records together with the scaling factors associated with the return period T R to perform the analysis. The engineering demand parameters (EDPs) are then evaluated in both building directions through NLTHs analyses performed with a simplified non-linear model implemented in the framework to reduce the computational demand and perform the simulation efficiently at the regional level. This model was developed and validated based on the results of a test campaign on full-scale multi-storey infilled RC frames under pseudo-dynamic loading protocol and the numerical results of a refined model developed in the SAP2000 environment (Computers & Structures Inc., 2016). It was validated at building level against the damage observed on a case study building selected by Del Vecchio et al. (2024). The approach and the assumptions adopted for the development, validation, calibration and simplification of the refined model are reported in Del Vecchio et al. (2024). More details of the refined model developed in SAP2000 can be found in Molitierno et al. (2023).

Fig. 1. Proposed simplified loss assessment framework.

The proposed model consists of a multi degree of freedom (MDOF) system with mass lumped at the floor level. The mass assigned to each DOF is the mass calculated considering the dead loads in the seismic combination calculated according to Eurocode 8 (2005). The lateral response of each floor is reproduced with non-linear springs considering the contribution of infills and RC columns. The nonlinear response of the RC frame is characterized for buildings designed for gravity load (GLD) and seismic loads (SLD) according to the procedure presented in Molitierno et al. (2025). Then, the non-linear response of the infill panels is modelled using the single strut model proposed by Panagiotakos & Fardis (1996). The lateral response of the model is assumed to be symmetric in both positive and negative directions. Moreover, the stiffness of beams and slabs is neglected in the model since the lateral response for infilled RC frames is well-approximated by a shear type frame in agreement with Del Gaudio et al. (2015). This is because most of the global stiffness and strength is provided by the infills. More details on the simplified non-linear model implemented in the framework can be found in Molitierno et al. (2025). The hysteretic response of the building is reproduced with the pivot model (Dowell et al., 1998) as suggested by Cavaleri & Di Trapani (2014) as it allows to capture the stiffness degradation and pinching effects of infills made with hollow clay brick, typical of the Mediterranean area. The parameters of this model were calibrated at the substructure and building level based on the experimental results of pseudo-dynamic tests on full-scale multi-storey infilled RC frames. Further details on the calibration of these parameters can be found in Molitierno et al. (2023). The EDPs obtained from the NLTHs analysis are used to perform the loss analysis (see Fig. 1). The number of drift-sensitive and acceleration-sensitive components for each story and direction of the building must be also defined. The FEMA P-58 (ATC 2018) component-based framework has been fully implemented in the proposed