A refined diffuse cohesive approach for the failure analysis in quasibrittle materials—part II: Application to plain and reinforced concrete structures

Abstract

This work presents the numerical application of the diffuse cohesive interface model introduced in the Part I paper to the failure analysis of plain and reinforced concrete structures, subjected to complex loading conditions, inducing mixed‐mode fracture initiation and propagation. With the aim of capturing the interaction between concrete and steel reinforcements, the adopted fracture model is incorporated in a novel, more general numerical framework for the nonlinear analysis of reinforced concrete structures. Such a framework includes a newly proposed embedded truss model for the reinforcing bars, allowing them to be crossed by the neighboring propagating cracks. Comparisons with available experimental results are provided, assessing the reliability and the numerical accuracy of the proposed concrete model, with reference to plain specimens subjected to single‐crack propagation as well as to reinforced elements subjected to multiple cracking.

Failure Analysis of Ultra High-Performance Fiber-Reinforced Concrete Structures Enhanced with Nanomaterials by Using a Diffuse Cohesive Interface Approach

“…This section is devoted to the presentation of the newly proposed numerical framework for the failure analysis of nano-enhanced UHPFRC structures, as well as of the related computational details. Such a framework is adapted from another integrated numerical model, previously introduced in [ 53 ] for conventional RC structures, to the case of steel bar-reinforced nano-enhanced UHPFRC structures.…”

“…This approach, whose theoretical background is briefly recalled in Section 2 , considers all the internal mesh boundaries as potential crack segments, modeled as cohesive interfaces equipped with a suitably calibrated mixed-mode traction-separation law. The desired feature of this approach consists in the possibility to simulate multiple crack onset and propagation without requiring externally introduced crack initiation criteria or computationally costly remeshing operations; an embedded truss model (ETM), used in synergy with a special sliding interface model, already adopted in [ 52 , 53 ] for conventional RC structures and here adapted to capture the enhanced steel/concrete bond-slip behavior provided by nano-reinforcements embedded in the UHPFRC mixture. …”

“…an embedded truss model (ETM), used in synergy with a special sliding interface model, already adopted in [ 52 , 53 ] for conventional RC structures and here adapted to capture the enhanced steel/concrete bond-slip behavior provided by nano-reinforcements embedded in the UHPFRC mixture.…”

Investigation of mesh dependency issues in the simulation of crack propagation in quasi‐brittle materials by using a diffuse interface modeling approach

“…The interface model adopted in the present work is the same as that already used by some of the present authors, 35,44 relying on an intrinsic cohesive law incorporating a nonlinear softening response of phenomenological type. The cohesive behavior of the interface elements inserted between adjacent bulk elements is described using a mixed‐mode traction–separation law written in the following matrix form: where is the interface traction vector appearing in the third term of left‐hand side of Equation 1.…”

“…The DIM approach possesses the advantage of naturally handling multiple cracking, including crack bifurcation and coalescence, without requiring any remeshing operations. Recently, some of the present authors have used the DIM approach for simulating the fracture behavior of concrete‐like structures subjected to both mode I and mixed‐mode loading 35–38 …”