PSI - Issue 78

Federico Gusella et al. / Procedia Structural Integrity 78 (2026) 113–119

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structures, respectively. The intensity measure IM = Se(T 1 ) is in units of [g], with T 1 the first period of vibration of the structure and Se(T 1 ) the elastic spectral acceleration at T 1 .

Table 1. Medians of fragility curves.

dm 1

dm 2

Design concept

(Development of damage) (Collapse) 1, (*) 2, = 1, 2, (*) (*) Medians corresponding to the achievement of the LSLS; LD structure D structure 1, = 2,

Fig. 1. Fragility curves for a Low-Dissipative (LD) structure and a Dissipative (D) structure.

The state of safety of structures is related to the annual failure rate λ f , which can be computed by combining the ground-motion hazard curve with the fragility function corresponding to the achievement of the damage state related to the LSLS ( d mLSLS ): =∫ ( ( / ) ) | ( > )| = − 1 2 2 2 (7) By Eq. (7) the median ( θ LSLS ) of the fragility related to the LSLS can be evaluated: =( 2 2 2 ) 1/ (8)