Ductility of corroded steel members and components

摘要

Following recent earthquakes that have demonstrated the potential seismic vulnerability of some types of steel bridges, many transportation agencies have initiated programs to evaluate the seismic resistance of their existing bridges. However, in numerous parts of North America, in case of inadequate maintenance in aggressive corrosion environments, seismic-resistant members frequently appear to be severely corroded. To determine whether such rusted members can reliably exhibit stable ductile behavior, a number of rusted pieces taken from an old steel bridge were subjected to tension and cyclic bending tests. Specimens had up to a 60percent loss of cross-sectional area due to corrosion. Non-cyclic tension stress-capacity and ductility did not change significantly due to corrosion. However, cyclic tests showed that, while stable hysteretic behavior comparable to that of unrusted specimen is possible, premature low-cycle fatigue typically develops. Irregularities along the rusted surface apparently act as crack initiators and precipitate crack propagation throughout the section. Finally, a few rivets tested in tension or shear did not exhibit any considerable degradation of strength nor ductility.