A combined ALE-cohesive fracture approach for the arbitrary crack growth analysis

Degradation analysis of dynamic properties for plain concrete structures under mixed-mode fracture conditions via an improved cohesive crack approach

“…Specifically, the nonlinear process induced by the crack propagation is simulated by a diffuse cohesive approach, proposed by some of the authors in [31], which has been here enhanced to suitably predict the frictional effects arising during the closure phenomenon of the crack faces in a compression loading state. Moreover, the dynamic properties of the damaged concrete specimens are detected by solving the modal model of the structural system thus obtaining natural vibration frequencies and mode shapes of the concrete specimens [25]. The proposed strategy is implemented in a 2D finite element framework by using the commercial software COMSOL Multiphysics.…”

“…In order to analyze the cracking processes in concrete structures subjected to loading/unloading conditions, the numerical formulation should incorporate concrete plasticity. As introduced by some of the authors in [25], such effect is considered by adopting the plastic contribution p n  and p s  for the normal and the tangential components of the displacement jump   u . Therefore, the components of the cohesive traction vector can be expressed as follows:…”

“…The dynamic response of reinforced concrete structures under defined damage states is determined by solving the small amplitude free oscillation problem of the discretized structural model using a displacement-based finite element approach, similar to that employed in [25]. Linearized equations of motion are derived for undamped dynamic systems, with the stiffness matrix considering nonlinearities from cohesive constitutive laws due to damage, plasticity, and partial contact phenomena.…”

“…Discrete fracture methods, including cohesive models [23,24], have the main advantage of appropriately predicting the crack pattern induced by the applied loads, as well as the complex damage phenomena typical of plain and reinforced concrete (RC) structures. Moreover, they are versatile and applicable to different types of quasi-brittle materials, such as concrete elements [25] and fiber-reinforced composite materials [26][27][28], RC structures strengthened with FRP systems [29,30], and RC beams enhanced with nanomaterials embedded in the concrete matrix [31][32][33]. Additionally, they combine reliability, in terms of expected results, and lower computational costs.…”

“…In the context of the structural health monitoring procedures based on the coupling between numerical models and experimental data, in this work, a numerical model has been developed to investigate the crack-induced degradation of vibration characteristics in plain concrete structures under mode I and mode II fracture conditions. In order to take into account all complex nonlinear phenomena, such as concrete crushing, concrete plasticity, and the friction effect during the unloading phase, an extension of the cohesive model proposed by some of the authors in [25] has been implemented in a 2D finite element framework. In particular, a cohesive zone model, used to predict the crack onset and propagation in the concrete phase has been successfully applied to analyze the structural behavior of concrete elements subjected to cycling loading conditions, taking into account both concrete plasticity and contact/friction effects between the crack faces during the unloading stage.…”