Modelling of load interaction and overload effect on fatigue damage of steel bridges

Abstract

This paper studies the effects of load sequence and interaction, and overloading effect on the fatigue damage of bridges on the basis of a non‐linear fatigue damage model. The model is derived from the theory of continuum damage mechanics for high‐cycle fatigue. Fatigue behaviour at two levels of constant stress range is first discussed in detail. The formulation for the effective fatigue strength of the predamaged members is then derived, and the results predicted by the model are compared with the experimental data for two stress level tests and other results obtained from linear and double linear fatigue damage models. The variation of cycle ratio and fatigue life due to overloading is secondly investigated; the equations for evaluating the effect of overloading on fatigue damage accumulation on bridges at normal traffic loading are then derived. It has been demonstrated that the developed model can well describe the effect of load sequence and interaction and has also been verified by comparing the predicted results obtained by the model with the experimental data based on two levels of stress tests. The effect of accidental overloading on the fatigue damage of existing bridges can also be evaluated using the model. The model is applied to evaluate the fatigue damage and service life of the Tsing Ma Bridge, an essential portion of the transport network for the Hong Kong airport, under normal traffic loading and possible accidental overloading.

A Practical Method for Determining the Corten-Dolan Exponent and Its Application to Fatigue Life Prediction

“…It was classified as a "load interaction effect" [17]. It is assumed that the load interaction effect is a result of the damage that occurs during those "transition cycles" between different constant amplitude segments, where the magnitude of the mean stress changes.…”

“…The parameter d within Corten-Dolan's model is a variable instead of being constant, thus it can be called the dynamic Corten-Dolan's model. Recent studies [16][17][18]30] show that the load interaction effect is a significant contributor to strength and life loss for low-high and high-low two-stress level tests with various load block sizes. The load-interaction factor, , is a nondimensional value determined by comparing fatigue life data from small block and large block two-stress level fatigue tests with predicted results.…”

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

“…For example, the cold and severely cold regions in China amount to 60% of the total land area, with the lowest service temperature at −53°C. 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. [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.…”

A nonlinear fatigue damage accumulation model considering strength degradation and its applications to fatigue reliability analysis

“…In order to remedy the shortcomings of Miner's rule, lots of researchers have done the works about the nonlinear damage accumulation theories, and there are extensive literatures concerning nonlinear damage models: continuum damage mechanics models (Besson, 2010;Dattoma et al, 2006;Yuan et al, 2013); energy-based damage methods (Jahed et al, 2007;Kreiser et al, 2007;Scott-Emuakpor et al, 2008); damage curve approaches (Manson and Halford, 1981); damage theories based on thermodynamic entropy (Risitano and Risitano, 2010;Naderi et al, 2010); damage rule considered the load interactions (Chen et al, 2011;Corten and Dolan, 1956;Li et al, 2001;Skorupa, 1999); damage theories based on physical property degradation (Cheng and Plumtree, 1998;Ye and Wang, 2001;Zhu et al, 2013). Though a number of works have been done in nonlinear damage accumulation, there are still some issues for nonlinear damage accumulation to be further researched especially in considering the effects of load interactions and the strength degradation of materials.…”