GB/T 13331-2013 is a dedicated standard for welded joint types in crane structures, defining the classification, configuration, and fatigue strength calculation of welded joints.

Standard Positioning and Structural Design Requirements

GB/T 13331-2013 (originally issued as JB/T 13331-2013 before conversion to a national standard) is the core standard for the structural design of welded crane frameworks. The standard establishes the following fundamental principles for the welding design of crane steel structures: welds should be located in areas of lower stress and kept clear of stress concentration zones. Weld dimensions must be determined by calculation rather than by experience alone; arbitrarily increasing fillet weld leg height is not permitted, as oversized welds lead to greater welding distortion and residual stress. When joining steel plates of different thicknesses, the thicker plate should be tapered on the welding side (transition slope ≤ 1:2.5). The fatigue strength of welds must be verified in accordance with GB/T 3811 Crane Design Standard. The structural design should also account for welding accessibility, ensuring that welding torches and operators can reach the weld positions for proper execution.

Welded Joint Types and Selection

The standard specifies the following joint types for crane welded structures: Butt joints — used for splicing the main girder flange plates and web plates. An I-shaped groove is used for plate thickness ≤ 8 mm, a V-shaped groove (60° groove angle) for thicknesses between 8 mm and 20 mm, and an X-shaped groove (double-sided welding to reduce angular distortion) for thicknesses exceeding 20 mm. T-joints — used for connecting web plates to flange plates (the main welds of the main girder). Partial penetration T-joints are suitable for light duty classification, while full penetration T-joints are required for critical welds rated A5 or above. Corner joints — used for connecting stiffening plates to web plates. Lap joints — to be avoided wherever possible for primary load-bearing members and used only for non-load-carrying components. The strength of butt welds must not be lower than the design value of the base metal strength. The fillet weld leg height must be no less than 4 mm and no greater than 1.2 times the thickness of the thinner plate.

Weld Calculation Methods

The standard provides calculation methods for various weld types: Butt welds — for butt welds subjected to axial tension or compression, the strength is calculated as σ = F/A ≤ f_t or f_c, where F is the applied force, A is the weld cross-sectional area (taken as base metal thickness × weld length, excluding reinforcement), and f_t and f_c are the design values of tensile and compressive strength of the weld, respectively. Fillet welds in T-joints — fillet welds subjected to shear force are calculated as τ = F/(h_e × l_w) ≤ f_v, where h_e is the effective throat thickness of the fillet weld (= 0.7h_f, with h_f being the leg height), l_w is the effective weld length (actual length minus 2 × h_f), and f_v is the design shear strength of the fillet weld. The standard also specifies strength check formulas for welds under combined stress (bending + shear + axial force) and fatigue strength verification methods, where the allowable fatigue stress range is determined based on the number of stress cycles.

Welded Joint Type Comparison Table

The comparison table below outlines the core parameter configurations for welded joint types, serving as a reference for design selection and field application.

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