EFFECT OF SEVERE CORROSION ON CYCLIC DUCTILITY OF STEEL

Although some past experimental studies indicate that the monotonic st ructural ductility of steel is not detrimentally affected by severe co rrosion, no study has investigated whether such severely rusted member s can reliably exhibit the stable cyclic ductile behavior necessary fo r seismic survival. To generate preliminary data, a few rusted pieces taken from an existing steel bridge have been subjected to numerous cy cles of alternating plasticity in flexure. Specimens had up to a 60% l oss of cross-sectional area because of corrosion. This limited test pr ogram revealed that, although stable hysteretic behavior comparable wi th that of unrusted specimen is possible, premature failure under alte rnating plasticity can typically develop (in spite of satisfactory duc tile behavior under monotonic loading). Irregularities along the sever ely rusted surface apparently act as crack initiators and precipitate crack propagation throughout the section.