PSI - Issue 64

Zhikang Deng et al. / Procedia Structural Integrity 64 (2024) 400–408 Zhikang Deng / Structural Integrity Procedia 00 (2019) 000 – 000

402

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Fig. 1. (a) Glass as structural element; (b) post-tensioned glass beam; (c) structural performance of a glass beam vs. a post-tensioned glass beam.

2. Materials Annealed glass was chosen for this investigation due to its economic advantages, although it has a lower strength compared to fully tempered glass (FTG) and heat-strengthened glass (HSG). Additionally, annealed glass fractures into larger fragments, which can improve the post-cracking performance of laminated glass beams. In this study, the selected glass has a Young's modulus of 70 GPa. Its characteristic tensile bending strength is 45 MPa, and it has a thermal shock resistance of approximately 40 K, along with a thermal expansion coefficient of 9 × 10 −6 K −1 , as specified in EN 572-1 (2016). The adhesive SikaPower®-1277 was considered in this investigation due to its good performance for the glass-to-Fe-SMA lap-shear joints investigated by Silvestru et al. (2022a) and the four-point bending tests conducted by Silvestru et al. (2022b). SikaPower®-1277 is a two-component epoxy, which has a glass transition temperature of approx. 67 ºC. The selected basic mechanical material properties of SikaPower®-1277 are shown in Table 1. The Young's modulus and lap-shear strength of SikaPower®-1277 decrease significantly when the temperature is increased from 23 ºC to 80 ºC. The degraded material properties of SikaPower®-1277 at elevated temperatures makes it crucial to investigate the thermal and mechanical behaviour of the glass-to-Fe-SMA joints at elevated temperatures.

Table 1. Selected basic material properties of SikaPower®-1277 from Sika (2021). Temperature Elastic modulus (MPa) Lap-shear strength (MPa)

Elongation at break (%)

23 °C 80 °C

1940 138

28 13

7.4 17

Fe-17Mn-5Si-10Cr-4Ni-1(V, C) (mass%) alloy was used in this research in the form of strips, pre-strained by 2.5%. This alloy was developed for the construction industry. The pre-strain can be partially recovered when the Fe-SMA is heated above a certain target temperature. The basic material properties of the Fe-SMA alloy were investigated by Silvestru et al. (2023), as presented in Table 2. The thermal expansion coefficient of Fe-SMA is 14.9 × 10 −6 K −1 as reported by Hosseini et al. (2018). Table 2. Selected basic material properties of Fe-SMA from Silvestru et al. (2023). Young's modulus (MPa) Ultimate tensile strength (MPa) Strain at ultimate tensile strength (%) 0.2% yield strength (MPa) 168,909 953.04 29.06 491.47