Issue 51

D. Vasconcelos et alii, Frattura ed Integrità Strutturale, 51 (2020) 24-44; DOI: 10.3221/IGF-ESIS.51.03

Original Foundation

Reinforced Foundation

Point

Stress Value 376.87 MPa 294 MPa 336.7 MPa

Point

Stress Value

V1 L1 N1

A2 B2 C2

21 MPa 29 MPa 32 MPa

Table 7 : Comparison of results between points of interest of the original foundation analysis and the reinforced foundation analysis, both using the springs formulation at 11.4 m s -1 .

Transient analysis at wind speeds of 24 m s -1 Fig. 27 shows the global model analysis at wind speeds of 24 m s -1 and Fig. 28 shows the results of the BC analysis at the same speed. The highest stress for the springs formulation is 113 MPa, yielding a safety coefficient of 3.11. For the displacements formulation, the highest stress verified is 210 MPa, achieving a safety coefficient of 1.668. Once again, the influence of singularities should be carefully analysed in future works.

Figure 27 : Global model analysis with springs formulation. Units in Pascal.

Figure 28 : BC analysis with the displacements formulation. Units in Pascal.

Properties

Original Structure

Final Structure

Steel Mass [Tonnes]

3 852 9 621 0.278 0.032

9 543 3 930

Overall Ballast’s Water Mass [Tonnes]

Fundamental Frequency [Hz]

0.6896

Lower Safety Coefficient at 11.4 m s -1

1.67

Analysis not performed

Lower Safety Coefficient at 24 m s -1

1.668

Table 8: Mode description and respective frequency.

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