Overlapping lattice modeling for concrete fracture simulations using sequentially linear analysis

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2017
Aydın, Beyazıt Bestami
Estimation of the crack location and width in concrete structures is important due to the sustained damage in structures as a result of extreme loads and aging. The location and width of cracks are the most influential parameters for making decisions on the structure service life. Despite significant developments, the computational modelling of concrete fracture initiation and propagation are still challenging tasks. Many different numerical approaches, most of them based on finite element analysis, have been used in the past employing the smeared or discrete cracking approaches. Such models lack the ability to capture local nature of cracking, the direction of crack propagation and require incorporating ad hoc approaches with extensive calibrations with tests. Recent studies in the last decade have focused on using particle based simulation methods (such as the discrete element method, the lattice-based methods, smoothed particle hydrodynamics, etc) to capture the local character of fracture phenomenon. Among these approaches, lattice modeling and particle based method of vi peridynamics have been used as non-local fracture simulation tools. Peridynamics can be viewed as an overlapping lattice approach in which continuum is discretized using pin connected bar elements extending over a predefined horizon. The advantages of these tools are the relative ease of modeling and the simulation of crack propagation using a few key parameters with the ability to bridge various scales from micro to macro levels. In this work, an overlapping lattice approach is proposed, where the continuum is discretized using truss elements extending over a predefined horizon similar to the concept used in peridynamics with the sequentially linear analysis (SLA) technique which is a non-iterative direct solution technique for nonlinear problems. The key difference of our application from the literature is the use of a classical structural analysis with SLA for the simulations as opposed to a particle based approach and a novel calibration of the constitutive model parameters using tension test results. Simulation results for several reinforced concrete (RC) and unreinforced concrete tests focusing on the influence of the mesh size, horizon and the softening functions on the sensitivity of results demonstrate the ability of accurately predicting the direction of crack propagation and the crack widths with the proposed modeling approach with a rather simple and intuitive method.