ABSTRACT
It is clear from the preceding chapter that concrete behaviour is an important constituent of the overall input required for the structural analysis of concrete structures. However, the modelling of concrete behaviour is fraught with difficulties. The first of these is the necessity of using triaxial-test data, namely that the material description should refer to the response of concrete under generalised (i.e., three dimensional) states of stress. As discussed in the preceding chapter, the reason for this is the large effect that small stresses, usually ignored in plane-stress analysis, have on concrete behaviour; this will become apparent throughout the following chapters of the book. The second source of difficulties associated with the establishing of actual properties of concrete materials relates to the scatter – and, thus, the reliability – of available experimental results. Not surprisingly, this apparent discrepancy of the failure envelopes and constitutive relations obtained by various laboratories and research groups working in this important field raises the question of whether or not a reliable model of concrete is at all possible, such that consistent and repeatable results might be obtained among a set of nominally identical specimens.
