PSI - Issue 64

Maria Ntina et al. / Procedia Structural Integrity 64 (2024) 2036–2043 Maria Ntina/ Structural Integrity Procedia 00 (2019) 000–000

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values of the stresses. The superelastic loops of the materials are shown in Fig. 2 and their properties are listed in Table 1.

Fig. 1. (a) View of the building under consideration; (b) SeismoStruct model; (c) The retrofitted section

Fig. 2. The superelastic loops: (a) Ni-Ti; (b) Cu-Al-Mn; (c) Cu-Al-Be

Table 1. Material properties of the SMAs considered. Material Properties

Ni-Ti

Cu-Al-Mn

Cu-Al-Be

Austenite-to-martensite starting stress (MPa)

323

142

136

Austenite-to-martensite finishing stress

383

265

200

Martensite-to-austenite starting stress (MPa) Martensite-to-austenite finishing stress (MPa)

250 112

180

133

72 25 12

40 17 22

37

Modulus of Elasticity (GPa)

Superelastic plateau strain length (%)

8

Pushover analysis was conducted to evaluate the performance of the initial unretrofitted and the retrofitted structures relating the base shear and the top displacement under loading combinations X+0.3Y and 0.3X+Y, employing uniform and modal load patterns. The analysis was executed considering the spectral type of the region of the building, a ground type B and a PGA of 0.24g, referred to a return period of 475 years. As depicted in Figs 3 and 4, all retrofit schemes increased the capacity of the structure and provided ductility. The steel retrofit scheme