Development of realistic concrete models including scaling effects
Progressive cracking in structural elements of concrete is considered. Two simple models are applied, which lead to similar predictions for the fracture behaviour. Both show a trend towards brittle behaviour and catastrophical events for large structural sizes. A numerical Cohesive Crack Model is proposed to describe strain softening and strain localisation in concrete. Such a model is able to predict the size effects of fracture mechanics accurately. Whereas for Mode 1, only untieing of the finite element nodes is applied to simulate crack growth, for Mixed Mode a topological variation is required at each step. In the case of the four point shear specimen, the load vs. deflection diagrams reveal snap-back instability for large sizes. By increasing the specimen sizes, such instability tends to reproduce the classical LEFM instability. Remarkable size effects are also theoretically predicted and experimentally confirmed for reinforced concrete. The brittleness of the flexural members increases with increasing size and/or decreasing steel content. On the basis of these results, the empirical code rules regarding the minimum amount of reinforcement could be considerably revised.
Bibliographic Reference: EUR 12392 EN (1989) 66 pp, FS, ECU 6.25
Record Number: 199010298 / Last updated on: 1994-12-01
Original language: en
Available languages: en