Experimentelle Untersuchungen zur Ermüdung des Verbundes von Stahlbeton unter Querzug

Experimental investigations on bond fatigue under transverse tension

An experimental program was carried out, which focused on investigating the bond behaviour between reinforcing steel and concrete under combined loading due to fatigue and transverse tension. The investigations for both, normal strength concrete and high performance concrete were performed on pull-out specimens with a longitudinal crack along the reinforcing bar due to transverse tension. High cyclic tests, of up to one million load cycles, were carried out for four different load levels with varying crack widths. The increase in slip between reinforcing steel bar and concrete relative to the number of load cycles was taken into account to compare various loading conditions. The influence of transverse tension on bond resistance under repeated loading became evident. The wider the longitudinal crack widths, the greater the increase in slip was and the earlier bond failure occurred. Based on slip development predictions, constant life diagrams were derived for fatigue design against bond fatigue failure.