Shear behaviour of reinforced concrete members without stirrups and subjected to fatigue loads

摘要

The shear fatigue behaviour of reinforced concrete elements without stirrups is a complex processrnthat involves a large number of variables. Because of its brittle nature, a better understanding ofrnshear fatigue is convenient, so that practical recommendations with mechanical basis can bernproposed. Experimental evidence indicates that shear fatigue failure starts with the formation of arndiagonal crack from the inclination of a flexural crack in one of the shear spans. This diagonal crackrnthen propagates with load cycles, both upwards to the load application point and downwards to thernsupport. Final shear fatigue failure takes place by the destruction of the compression zone when itsrndepth is too small to resist the compression force acting on it. In addition, it is also possible anrnunstable propagation of the diagonal crack as soon as it forms. A critical point of the process isrntherefore the formation of the diagonal crack. In this paper, the capabilities of a predictive model tornestimate the number of cycles to diagonal cracking are explored. A comparison is carried out withrnfirst experimental results on haunched reinforced concrete beams without stirrups, which are typicalrnof cantilever slabs of bridge decks.