The behavior of crack growth with a view to fatigue damage accumulation on the tip of
cracks is discussed. Fatigue life of welded components with initial crack in bridges under traffic
loading is investigated. The study is presented in two parts. Firstly, a new model of fatigue crack
growth for welded bridge member under traffic loading is presented. And the calculate method of
the stress intensity factor necessary for evaluation of the fatigue life of welded bridge members with
cracks is discussed. Based on the concept of continuum damage accumulated on the tip of fatigue
cracks, the fatigue damage law suitable for steel bridge member under traffic loading is modified to
consider the crack growth. The proposed fatigue crack growth can describe the relationship between
the cracking count rate and the effective stress intensity factor. The proposed fatigue crack growth
model is then applied to calculate the crack growth and the fatigue life of two types of welded
components with fatigue experimental results. The stress intensity factors are modified by the factor
of geometric shape for the welded components in order to reflect the influence of the welding type
and geometry on the stress intensity factor. The calculated and measured fatigue lives are generally
in good agreement, at some of the initial conditions of cracking, for a welded component widely
used in steel bridges.
An Improved Spectral Analysis Method for Fatigue Damage Assessment of Details in Liquid Cargo Tanks