Computational model for crack simulation in concrete beams using interface elements

Resumo

The study of damage in concrete structures plays an essential role in evaluating its useful life and
integrity, preventing disasters, and defining the need for maintenance or reinforcement in the structure. Among
the common pathologies that occur in reinforced concrete structural elements, there is cracking. Despite being
unavoidable due to the concrete’s low tensile strength compared to its compressive strength, it is essential to know
the behavior of the material before and after cracking starts, investigate its causes, limiting the level of crack
opening to guarantee a good performance of the structure. Therefore, the present work aims to study cracked
concrete beams modeled as a plane stress state, submitted to different loading and boundary conditions situations.
A computational crack model was developed based on the Finite Element Method with conventional quadrilateral
isoparametric elements and interface elements with five springs extracted from the literature. These interface
elements allow the simulation of cracking opening in regions where the tensile stresses are higher than the concrete
strength. The constitutive model for the interface element depends on a penalty parameter empirically inserted to
simulate the reduction of material stiffness when subjected to tensile stresses. To avoid shear-locking, reduced
integration was adopted together with techniques for controlling the hourglass modes in such under-integrated
elements. This model has been implemented using the software MATLAB and the results were validated by
comparing with the ones of other authors, showing good agreement.