Fatigue performance of tubular X-joints with PJP+ welds: II — Numerical investigation

Fatigue performance of tubular X-joints with PJP+ welds: I — Experimental study

“…The maximum SCF value at the weld root equals approximately 90% of the SCF value at the weld toe. The numerical investigation coupled with the Paris law estimation in the companion paper [37] confirms that the root crack initiates later than the fatigue crack at the weld toe. Fig.…”

“…The measured propagation angles for all weld toe cracks remain positive and in the range of 10°to 30°. The companion paper [37] examines the mixed-mode stress-intensity factors for different crack propagation angles.…”

“…The companion paper[37] examines the interaction among multiple cracks along the brace-to-chord intersection on the fatigue driving force.…”

Translating the material fracture resistance into representations in welded tubular structures

“…This study, therefore, examines the reported material J-R curves for a wide range of structural steel materials and proposes a lower-bound J-R curve for small-scale yielding, high-constraint conditions. Previous investigations [73] have confirmed the high crack-front constraints for surface cracks in welded tubular joints, reflected by the positive T-stresses. This linear, lower-bound J-R relationship remains valid up to a small amount of crack extension, Da true ¼ 2 mm, which prevents severe local unloading in materials near the crack tip.…”

Fatigue crack propagation for Q345qD bridge steel and its butt welds at low temperatures

“…1 The safety of such infrastructures has posed a critical concern for countries residing in the cold region. [8][9][10][11][12] However, the Paris material constants used in estimating the fatigue life in these design codes derive primarily from the experimental database recorded at the room temperature. 2,3 A number of design procedures [4][5][6][7] have evolved for the fatigue prone structural details, based on a Paris type crack propagation rule, to assess the fatigue performance of steel bridges and Nomenclature: a, = crack length; a 0 , = initial crack length at the end of fatigue pre-cracking; A, = percentage of elongation at fracture; B, = thickness of the compact tension, C(T), specimen; C, = Paris-law coefficient; C 0 , = coefficient of stress intensity factor gradient method; E, = elastic modulus; f y , = yield strength; f u , = ultimate tensile strength; K I , = stress intensity factor; ΔK I , = stress intensity factor range; ΔK th , = fatigue crack propagation threshold; m, = exponent of the Paris-law; N, = number of loading cycles; P max , = maximum load; ΔP, = applied cyclic load range; R, = stress ratio; R 2 , = correlation coefficient; T, = temperature; T 27J , = fracture ductile-to-brittle transition temperature at which the Charpy impact energy is 27 J; T SA , = fracture ductile-to-brittle transition temperature at which the percent shear area of fracture surface in a Charpy specimen is 50%; T t , = fracture ductile-tobrittle transition temperature based on Boltzmann function; W, = width of compact tension, C(T), specimen; Z, = percentage of area reduction other welded steel structures.…”