PSI - Issue 44

Paola Sorrentino et al. / Procedia Structural Integrity 44 (2023) 1300–1307 Paola Sorrentino et al. / Structural Integrity Procedia 00 (2022) 000–000

1304

5

2.3. Miyazaki (2008)

The set used by Miyazaki to define the Next Generation of Seismic Isolation consists of 26 earthquake motions, of which 22 are strong motion records with maximum ground velocity equal of greater than 100 cm/s recorded in or near the source region in the USA, Taiwan and Japan and 4 are theoretically derived, long-period ground motions which have been proposed by earthquake researcher (Miyazaki, 2008). In Figure 6 the acceleration and displacement response spectra are given. For periods lower than 1s, the acceleration spectra are characterized by values higher than 2g, as 5g at 0.32s for Tarzana Station spectrum (1994 Northridge Earthquake); instead, for long periods, they exhibit values up to 0.5g, as the spectrum of the 2007 Chuetsu-oki Earthquake, NIG018 Station with 1.28g at 2.2s (Figure 6a). In Figure 6b the displacement response spectra exhibit an increasing trend with increasing period, with values up to 80 cm for higher periods, as the 2007 Chuetsu-oki Earthquake, NIG018 Station with 180cm, the 2008 Iwate-Miyagi Earthquake, MYG005 Station with 130cm and the 1979, Imperial Valley Earthquake, Array 6 Station with 120cm (Figure 6b).

1971, San Fernando - Pakoima Dam 1979, Imperial Valley - Array 6 1979, Imperial Valley - Array 7 1994, Northridge - Olive View 1994, Northridge - Tarzana 1995, Kobe - KJMA 1995, Kobe - Port Island 1995, Kobe - Takatori 1999, ChiChi Taiwan - CHY028 1999, ChiChi Taiwan - CHY080 1999, ChiChi Taiwan - TCU071 1999, ChiChi Taiwan - TCU084 2000, Tottoriken Seibu - TTRH02 2003, Tokachi-Oki - Tomakomai 2004, Niigata - NIG019 2007, Notohanto-Oki - Anamizu ISK005 2007, Chuetsu-oki - NIG018 2008, Iwate-Miyagi - MYG005 Envelope

100 120 140 160 180 200

7

6

5

4

0 20 40 60 80

3

acceleration (g)

2

displacement (cm)

1

0

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3

T (s)

T (s)

(b)

(a)

Figure 6. Miyazaki (2008) spectra. Spectral accelerations (a); Spectral displacements (b).

2.4. Suzuki and Iervolino (2017)

Suzuki and Iervolino (2017) have selected ground motion records worldwide having the largest values of PGA and PGV, to compare the global trends with the values observed in Italy since 1972. In terms of response acceleration spectra (Figure 7a), these signals show a visibly increasing trend. This can be related to: the improvements of monitoring networks; the growing number of seismic arrays for recording ground motions; the consequent availability of a great number of strong motion data.

14

140

1933, Long Beach - Long Beach Utilities 1940, Imperial Valley - El Centro 1971, San Fernando - Pacoima Dam 1985, Nahanni - NWTSStation1 1992, Cape Mendocino - Cape Mendocino 1994, Northridge - Tarzana 2008 Iwate-Miyagi - Higashinaruse 2011, Tohoku - Tsukidate Envelope

12

120

10

100

8

80

6

60

4

acceleration (g)

40

2

20

displacement (cm)

0

0

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3

T (s)

T (s)

(a)

(b)

Figure 7. Suzuki and Iervolino (2017) spectra. Spectral accelerations (a); Spectral displacements (b).