A Pointwise Model Based on a Total Strain Approach to Simulate Long-term Concrete Behaviour

Ensuring the durability of reinforced concrete structures through numerical analysis requires addressing complex multiphysics phenomena that govern the evolution of volumetric deformations, strength and stiffness. The global structural response is significantly influenced by spatially varying properties, highlighting the need for advanced numerical tools to accurately account for these localized effects. This paper presents a pointwise thermo-hygro-mechanical (THM) model for 3D finite element simulations designed to perform numerical analysis of concrete behaviour throughout its service life. The mechanical properties of concrete are modelled based on the local hygrothermal properties. Concrete maturity is simulated using the equivalent age concept. The viscoelastic behaviour of concrete is described through the microprestress solidification theory. Key innovation is a new algorithm for integrating time-dependent mechanical properties into total strain crack models, assuming adaptive stress-strain relationships incorporating rotating and fixed crack concepts. The pointwise THM model is validated at the structural level through numerical simulations of experimental tests in reinforced concrete (RC) elements, assessing its ability to predict early-age stresses, crack patterns in thick members, and long-term shrinkage effects on the crack opening. Conclusions are based on the model’s efficacy in simulating the structural response of RC structures from early ages through their service life.