A smeared-fixed crack model for FE analysis of RC membranes incorporating aggregate interlock

This paper reports the development of the cracked membrane model using a fixed-crack approach for the finite element modelling of orthogonally reinforced structural elements under plane stress. The model falls into the broad category of compression field models" combining elemental components from the modified compression field theory with those of the tension chord model. The tension stiffening effect is developed using a steel-concrete bond relationship with its basis in limit analysis. With this approach the tension stiffening and tension softening components of the concrete tension resistance mechanism are decoupled allowing for rational models for each component. With adoption of a fixed crack formulation aggregate interlock along the cracks is explicitly modelled allowing for modelling of reinforced concrete members containing no or low quantities of steel reinforcement where slip along cracks significantly affects the results. For example, the modelling of shear critical beams containing low shear reinforcement volumes. The model has been incorporated into the finite element program for the analysis of reinforced concrete structures with verification of the finite element model presented.