Onthesize-effect phenomenoninconcretestructures

A fresh interpretation of existing experimental data, combined with what one could aptly describe as numerical experiments, leads to a new explanation of the underlining causes for size effects in structural concrete. Such an outcome is based on the premise that one must interpret correctly physical phenomena before attempting to put forward mathematical theories which, as so often in the past, l)bfuscate rather than elucidate, the nature of the so-called size effect in certain types of concrete members. This is the result of recent collaborative research between the National Technical University, Athens (NTUA) and Imperial College, London (ICL). a collaboration which is currently being extended so as to also encompass the Nanyang Technological University, Singapore (NTUS). I. INTRODUCTION span-to-depth ratio is presented so as to enlarge the range of problems considered earlier. It is widely believed that the behaviour of structural concrete, as predicted by methods of analysis such 2. EFFECT OF SMALL ECCENTRICITY OF as the finite-element (FE) method, is significantly APPLIED LOADING affected by the size of the member analysed. This size effect on the predicted behaviour is generally Most of the research on size effects to date has been attributed to inadequate modelling of the material confined to conditions of implicit load symmetry. properties and, thus, much of current research is However, while such conditions can readily be focused on improving material modelling which is imposed in numerical analysis, in real structures it often based on sophisticated fracture-mechanics is impossible to prevent the occurrence of out-of- postulates. However, theoretical considerations can plane actions. What is implicitly assumed is that.