Finite Element Modelling of Reinforced Concrete and Advanced-Material Beam–Column Joints: A Review with a Gradient-Regularised Microplane Damage–Plasticity Case Study

Abstract: Reinforced concrete (RC) beam–column joints remain one of the most extensively investigated yet persistently challenging regions of framed structures, since they must transfer large, reversing shear forces through a compact, congested volume of concrete. This paper reviews the evolution of finite element (FE) approaches used to simulate beam– column joint behaviour, tracing the progression from classical pressure-sensitive plasticity models through continuum damage mechanics to coupled plasticity–damage and microplane formulations, culminating in the Gradient-Enhanced Plasticity-Damage Microplane (GPDM) model now implemented in ANSYS as the CPT215/CPT216 element families. Building on this theoretical foundation, the review synthesises recent experimental and numerical studies across three connection families: conventional reinforced concrete joints, joints constructed with Ultra-High-Performance Concrete (UHPC) and steel-fibre-reinforced concrete (SFRC), and steel or steel–concrete composite beam-to-column connections. To ground the review in a concrete demonstration, the paper presents a case study in which the GPDM model was applied to a benchmark exterior T-shaped RC joint (specimen JA-0, after Chalioris et al., 2008) under monotonic displacement- controlled loading. The FE model predicted a peak reaction force of 32.9 kN at 33.8 mm beam-tip displacement, within 4.4% of the experimentally reported peak, and reproduced the joint’s characteristic elastic, hardening and post-peak softening phases, together with a shear-dominated failure mechanism consistent with the reported damage pattern. The synthesis identifies three converging research gaps — limited systematic mesh-sensitivity studies of gradient-regularised models for RC joints, an immature numerical toolkit for UHPC and SFRC connections, and under-exploited cross- fertilisation between steel/composite and RC joint research — and outlines directions for future work, including cyclic loading, bond-slip modelling and full-frame extensions.

Keywords: Beam–column joint; finite element analysis; ANSYS; microplane theory; damage plasticity; Ultra-High- Performance Concrete; seismic performance; mesh sensitivity.