Modelling of reinforced concrete members for high impulsive loading

RC components subjected to high dynamic loadings tend to undergo two main phases of response, namely a shock and stress wave phase, and structural response phase. The structural response phase may be further divided into three consecutive stages represented respectively by intense shear near the support, intense shear over a relatively small shear span, and global bending. Because the governing mechanisms are very different in different phases and stages of the response, modelling of the response of concrete components under such impulsive load becomes particularly challenging, and it requires the modelling of the concrete material to be capable of simulating confined compression, tension, shear and the interaction between concrete and steel within the same model framework. This paper presents an overview of the development of a general model for RC components (beams in particular) for the analysis under impulsive loads. To cater for the complex and high nonlinearity involved in the responses, the analysis is carried out using general purpose dynamic analysis software (LS-DYNA) with an explicit scheme. The constitutive model for concrete is evaluated and calibrated comprehensively for various stress conditions, and its behaviour in terms of preserving a realistic concrete-reinforcing bar interaction is scrutinised. A representative RC beam/slab is then modelled and analysed with a particular interest in looking into the development of the shear forces during the transient stage of the response and the shear resistance. The trends of decreasing shear span and increasing shear resistance are observed based on the numerical simulation results.