Fatigue of Reinforced Concrete Beams in Air, Chloride Solution, and Sea Water
H. Roper and G. B. Hetherington
Appears on pages(s):
tests; reinforcing steels; sea water
es; corrosion; cracking
fatigue (materials); fatigue
Fifty concrete beams reinforced with 24 mm deformed bars in the tension zone, were subjected to sinusoidal load fluctuations at 6.7 Hz in air, 3 percent sodium chloride solution and natural sea water. Total numbers of cycles at failure varied between 10' and lo7 for calculated stress ranges in the steel between 100 MPa and 280 MPa. Two types of tension reinforcement were compared; one was a hot-rolled 230 Grade deformed bar, and the second a cold.-worked 410 MPa Grade deformed similar chemical composition. bar with a As practised in some countries, cold-working by twisting was found to reduce the fatigue endurance of the deformed reinforcement in concrete beams tested both in air and sea water. The detrimental effect of sea water or sodium chloride solution gaining access, via concrete cracks, to bars subjected to fatigue loading was confirmed. In sea water the influence of cyclic loading on the hot-rolled series was different to that on the cold-worked series; for the latter series a decrease in slope of portion of the S-N curve was observed, which may represent a fatigue limit within lo7 cycles, whereas for the former no such change in slope exists. A reduction of fatigue endurance was observed for tests in a 3 percent sodium chloride solution compared with data for beams loaded in natural sea water. when A fractographic investigation was conducted on typical failure surfaces of bars subjected to tests in concrete,in air, and in sea water.