Issue 37

P.S. van Lieshout et al., Frattura ed Integrità Strutturale, 37 (2016) 173-192; DOI: 10.3221/IGF-ESIS.37.24 184 This is in agreement with various guidelines for the marine industry (e.g. [55-56]). The directionality of the two spectra was fixed at a 180 degrees heading for wind seas and a 90 degrees heading for swell. It was assumed that wind driven and swell seas are long-crested and generate only normal and shear stresses, respectively. Additionally, it was assumed that stress spectral density functions are the same as wave spectra - meaning that unit response amplitude operators were assumed. Normally, multiplication of the wave spectra with response amplitude operators slightly shifts the spectra towards another frequency range. Therefore, it was necessary to choose the spectra parameters such that they correspond to a realistic structural response of a typical marine structure. The used spectra parameters are listed in Tab. 4 and the corresponding energy density spectra are depicted in Fig. 6. The selected VA case is representative for a general fillet welded connection in a marine structure (see Fig. 7). It is supposed that along the weld a multiaxial stress state is generated consisting of a normal stress induced by wind seas and a shear stress induced by a simultaneous swell. Figure 6 : Energy density for wind seas and swell. Parameter Description Value ,  p wind T Peak period of wind seas 8 s ,   p swell T Peak period of swell seas 14 s ,  s wind H Significant wave height of wind seas 2 m , s swell H Significant wave height of swell seas 2 m g Gravitational constant 2 9.81 / m s  Gaussian spectral width 0.02  Peakedness factor of JONSWAP spectrum 3.3 Table 4 : All parameters which have been used to describe the two spectra of swell respectively wind seas.