Study on Reasonable Hole Diameters for Fatigue Crack Drilling in Steel Bridge Deck

Based on numerical simulation and fatigue tests, different types of crack were simulated and local full-scale specimens of typical fatigue details in steel bridge deck were designed for drilling. The relationship between the reasonable hole diameter, stress intensity factor K at the crack tip and yield strength sigma(ys) of the base metal was explored. The result demonstrates that the reasonable hole diameter is linearly related to K-2/sigma(2)(ys). The larger the ratio of K-III/K-I, the smaller the reasonable diameter required. Considering that K-III cannot be measured in real bridges, taking K-I 2/sigma(ys) as the basis for diameter selection can ensure a large surplus. The method of determining the hole diameter by K and sys is applicable when the crack length is relatively short compared with the boundary size. In addition, the stress intensity factor measured by the two-strain-gage method is slightly higher than that calculated by extended finite element method, with an average error of about 10%, which has the accuracy required for real-bridge application.