Fillet welds are checked according to GB 50017 - Chapter 11. The strength of butt welds is assumed the same as the base metal and is not checked.

### Butt welds

Full penetration butt welds are expected and their resistance is considered equal to that of the parent metal – Cl. 11.2.1.

### Fillet welds

Design resistance of fillet welds is checked according to Cl. 11.2.2.2:

\[ \sigma_w = \sqrt{ \left ( \frac{\sigma_f}{\beta_f} \right ) ^2 + \tau_f^2} \le f_f^w \]

where:

*σ*_{f}– stress on the effective area of the weld perpendicular to the weld length*β*_{f}– enlargement coefficient for design value of fillet weld strength;*β*_{f}= 1.22 for static loading and angle between fusion faces*α*= 90°; otherwise*β*_{f}= 1.0*τ*_{f}– shear stress on the effective area of the weld parallel to the weld length*f*_{f}^{w}– design fillet weld strength

Design fillet weld strength *f*_{f}^{w} for welding electrodes; derived from Table 4.4.5

Electrode | \(f_f^w\) [MPa] |

E43 | 160 |

E50 | 200 |

E55 | 220 |

E60 | 240 |

Default electrodes are E43 for weakest connected plate with *f*_{u} < 470 MPa, E50 for 470 MPa ≤ *f*_{u} < 520 MPa, and E55 for 520 MPa ≤ *f*_{u}.

The weld diagrams show stress according to the following formula:

\[ \sigma = \sqrt{ \frac{1}{\beta_f^2}(\sigma_{\perp}^2 + \tau_{\perp}^2) + \tau_{\parallel}^2 } \]