Concrete Mechanics for Performance Based Design

Example Interfaces in composites: pulling a rebar out of a matrix
Key to composite response are interfaces. For instance, reinforced concrete works only because the matrix cracks and the steel slips against it. Here a single rebar is pulled out of a concrete cylinder on a 3D lattice, with a plasticity bond in which slip generates a normal plastic strain that splits the matrix.

Example Packing aggregates into a periodic concrete RVE
Ellipsoidal aggregates are placed in a periodic concrete RVE using a trial and error approach.

Example Buckling of a strut, elastic and elasto-plastic, with a rigid-body lattice
A slender strut is compressed until it buckles. Elastic, the load rises above the critical load as the strut deflects. Elasto-plastic, a plastic hinge forms and the load drops. Both come from the same large-rotation lattice element, checked against the exact solution of a perfect strut.

Paper 3D frame element for large rotations based on the rigid-body-spring concept for analysing the failure of structures
Gumaa Abdelrhim, Peter Grassl, International Journal of Solids and Structures, vol. 327, pp. 113812, 2026.
DOI (Open access)

Paper RAAC panels can suddenly collapse before any warning of corrosion-induced surface cracking
Evžen Korec, Peter Grassl, Milan Jirásek, Hong S. Wong, Emilio Martínez-Pañeda, npj Materials Degradation, vol. 9, pp. 44, 2025.
DOI (Open access)

The Grassl Group, based at the James Watt School of Engineering at the University of Glasgow, aims to understand, predict and improve the response of concrete and concrete structures. Our work is focused on deterioration processes, development of new materials, optimisation of material use, repair and strengthening techniques, and response of structures subjected to accidental loading. Currently, our methodologies comprise the following areas: Meso/Micro scale modelling, Constitutive modelling and Structural modelling. We contribute to the development of the finite element program OOFEM. You can find all our models implemented in our github fork of OOFEM. Our results are described in our publications.