The Theory of Critical Distances to assess failure strength of notched plain concrete under static and dynamic loading

摘要

The Theory of Critical Distances (TCD) is a design method that is widely used in situation of\udpractical interest to estimate the strength of notched/cracked components subjected to either\udstatic, dynamic, or fatigue loading. The TCD makes use of a characteristic length to post-process\udthe linear-elastic stress fields damaging the material in the vicinity of the stress concentrators\udbeing designed. The employed length scale parameter depends on the specific microstructural\udfeatures of the material under investigation. By making the most of the TCD’s unique features, the\udpresent paper summarises an attempt of reformulating this powerful theory to make it suitable\udfor assessing static and dynamic strength of notched plain concrete. The accuracy and reliability\udof the proposed reformulation of the TCD is checked against a number of experimental results\udthat were generated by testing, under different displacement rates, square section beams of plain\udconcrete containing notches of different sharpness. This validation exercise allowed us to\uddemonstrate that the proposed reformulation of the TCD, which is based on the use of simple\udpower laws, is capable of accurately assessing the static and dynamic strength of the notched unreinforced\udconcrete being tested, with the estimates falling within an error interval of ±20%. The\udobtained level of accuracy is certainly satisfactory, especially owing to the fact that static and\uddynamic strength is predicted without explicitly modelling those non-linearities characterising\udthe stress vs. strain dynamic behaviour of concrete.