PSI - Issue 44

Francesco Morelli et al. / Procedia Structural Integrity 44 (2023) 574–581 Francesco Morelli, Agnese Natali, Gabriele Poggi / Structural Integrity Procedia 00 (2022) 000–000

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the Eurocode 8 spectrum using REXEL software. The IDA analyses allowed to assess the structural response of the system for different levels of seismic intensity, obtaining a complete picture of the structural behavior and the evolution of the damage for each structural element. These analyses were then used as a reference for the development of the simplified analysis procedures. Fig. 7 shows the results of the IDA analysis for each of the 30 accelerograms together with the main IDA curve. a b

Fig. 7. IDA curves with critical performance points highlighted: (a) single records; (b) and mean curve.

To develop a reliable simplified procedure, it is important to find a correlation between the results of pushover analyses and IDA analyses. Pushover analyses are classically represented in graphs that relate the value of the displacement at the top of the structure with the base shear, consequently also the results of the IDA shall be represented in the same way. It is important to note that the elaboration of the IDA curves can be done in several ways, some of them shown in Fig. 8 and described below: • : for each value of PGA, the maximum value of the displacement at the top of the structure matches the maximum value of the base shear. These two values can be reached in different instants of the analysis. • ( max ) : for each value of PGA, the maximum value of the displacement at the top of the structure matches the corresponding shear base. • ( ) : for each value of PGA, the maximum value of the shear base matches the corresponding displacement at the top of the structure.

Fig. 8. Some of the possible IDA curves elaborations for the case study considered.

The difference between the curves highlights that the maximum displacement at the top of the structure and the