THE EARLY STAGE PROPAGATION AND DELAYED INSTABILITY OF CRACK IN CONCRETE

This paper provides afailure model of the crack tip from the fact that the concrete presents visible viscoelastic under the long-time and continuous action of load,and according to the date given by modern examing and observing techniques for tensined concrete samples having a notch.The general laws have thus been researched for the early stage propagation and delayed instability of cracked conerete by the action of long-time and sustained load.Therefor,it is of practicle signicance to predict the service life of delayed crack instability for the concrete strctures during long period operation.