Scaling laws in concrete structures

Abstract

There are many experimental evidence on the existence of size effect in concrete structures. The problem has two aspects - statistical and deterministic. Although the statistical aspects are not negligible, in the present paper it is demonstrated that the scaling law is controlled by the structural energy release due to cracking. If a stable crack growth before reaching peak load is possible strong size effect may be expected. For infinitely large structures of these type scaling law based on the linear elastic fracture mechanics must be used. On the contrary, concrete structures fail at crack initiation without any size effect i.e. scaling law based on the strength criteria apply. Due to the finite size of the concrete fracture process zone, size effect for any small structure must exist. Recent numerical investigations using sophisticated numerical tools show that there are many practical examples which exhibit extensive cracking in smaller size range and almost no cracking in larger size range i.e. by increasing size failure mechanism is changing. Practical implication of this is that the size effect may disappear in the case of many large concrete structures. Although this has a strong mechanical background it can also be interpreted from the multifractal damage point of view.