Objective modelling of reinforced concrete planar frame sub-systems under extreme loading

This paper proposes a novel numerical modelling approach for the practical assessment of reinforced concrete planar frame sub-systems subject to extreme loading and robustness scenarios such as sudden column loss. The proposed approach utilises reinforced concrete and steel fibre beam-column elements formulated with the following features: i) explicit modelling of nonlinear bond-slip behaviour along the whole length of the reinforced concrete member, where the bond behaviour is encapsulated within a layer of the steel beam-column element; ii) compared to other published explicit bond-modelling approaches, the present approach reduces the number of nodes required in the definition of models and avoids the use of link elements for modelling bond-slip; and iii) practical representation of reinforced concrete planar frame sub-systems with sophisticated reinforcement detailing, including reinforcement curtailments and lap splices, under which each reinforcement bar can be modelled individually. A steel material model with tensile softening and a strain-dependent bond-slip model are also developed such that the proposed modelling approach is made readily available to predict the fracture of reinforcement and the influence of yield penetration. Following a detailed exposition of the element and material model formulations, several numerical and validation studies are presented to demonstrate the effectiveness of the proposed modelling approach.