Conference Agenda

Steel-plate concrete (SC) structures are increasingly adopted for protective infrastructure due to
their superior energy absorption and robustness under extreme loading. However, the influence of internal connectors under high-velocity impact remains insufficiently understood. This study evaluates the effects of shearstud spacing and tie-bar configuration on the impact resistance of SC panels using a detailed three-dimensional LS-DYNA model. The Karagozian & Case (K&C) concrete model with a user-defined dynamic increase factor calibrated from SHPB tests was employed to capture strain-rate-dependent concrete behavior. Steel faceplates and connectors were modeled with rate-sensitive plasticity and explicit steel–concrete interaction. Parametric analyses revealed that closer connector spacing enhances composite action but may intensify localized damage near the impact zone, whereas tie-bars improve through-thickness confinement and reduce global bulging. Numerical trends showed good agreement with available experimental results. These findings will directly inform an upcoming gas-gun experimental program and support improved design strategies for SC structures under extreme impact loading.

This study presents a poromechanical approach for analysing fire-induced fractures and mass transport phenomena in reinforced concrete (RC) structures. The model integrates multiphase flow and gaseous kinetics within the multi-scale simulation platform, enabling coupled evaluation of vapour pressure, cracking, and moisture migration under extreme thermal conditions. Comparisons with the diffusion model demonstrate that the poromechanical model captures localized rapid transport along cracks and provides more realistic pre-dictions of thermal damage. The poromechanical model is further applied to assess the post-fire performance of scaled cylindrical RC walls representing the reactor pressure vessel pedestal in a nuclear power plant. Sim-ulation results show that rehydration during post-fire curing contributes significantly to strength recovery after 400 °C heating, while severe degradation occurs at 800 °C heating. The proposed poromechanical model offers a rational and safety-oriented tool for evaluating RC structures under high-temperature exposure.

Delayed Ettringite Formation (DEF) is a concrete swelling pathology where early age elevated temperatures cause sulfate release, which can later precipitate as ettringite in the presence of moisture, leading to serious structural damage. Many structures built in the late 1990s now show symptoms, yet predicting their residual capacity and the reaction’s evolution remains difficult. French guidance recommends thermo-hydro-chemo-mechanical (THCM) modelling when crack growth is rapid or long-term performance assessment is needed (Godart & Divet 2018). Sellier & Multon (2018) then proposed a model to simulate the effect of DEF on concrete structures, but it faces large input uncertainties because key data are often unavailable years after construction. This study aims to identify the most influential input parameters for simulating DEF-affected concrete structures via a comprehensive sensitivity analysis on a bridge pier.

Solid reinforced concrete structures, such as pile caps and anchor blocks, are characterised by complex threedimensional stress states. Today, a widely adopted design tool that can reliably determine the stress field in solid reinforced concrete structures under serviceability limit state conditions is lacking. Current design practice often relies on hand calculations, such as the strut-and-tie method or even simple linear elastic models. Consequently, the design and verification of these structures are both very time-consuming and tend to be conservative. This leads to designs with excessive material usage and low utilisation. While advanced non-linear finite element methods offer detailed analysis of these structures, their practical application is often limited by numerical instabilities and the need for many material parameters, which may not be practical during the initial design phase. Finite element limit analysis provides a more efficient alternative, using rigid plastic models and convex optimisation. However, though suitable for ultimate limit state calculations, such models are incompatible with serviceability requirements, where an accurate representation of the cracking phase is needed. In this paper, a design-oriented tool for analysing solid reinforced concrete structures is introduced. The method uses the principle of minimum complementary energy and convex optimisation in a finite element framework to determine the structural response for a simulated elasto-plastic material model. The reinforcement can be modelled as smeared or as discrete bars embedded in the tetrahedral elements. The method is validated against a simple example with an analytical solution and against existing numerical methods. Finally, the method is applied to a complex example, demonstrating numerical stability and efficiency in capturing the structural response for a non-linear material model.