Comparison of the quasi-static method and the dynamic method for simulating fracture processes in concrete

Abstract

Concrete is heterogeneous and usually described as a three-phase material, where matrix, aggregate and interface are distinguished. To take this heterogeneity into consideration, the Generalized Beam (GB) lattice model is adopted. The GB lattice model is much more computationally efficient than the beam lattice model. Numerical procedures of both quasi-static method and dynamic method are developed to simulate fracture processes in uniaxial tensile tests conducted on a concrete panel. Cases of different loading rates are compared with the quasi-static case. It is found that the inertia effect due to load increasing becomes less important and can be ignored with the loading rate decreasing, but the inertia effect due to unstable crack propagation remains considerable no matter how low the loading rate is. Therefore, an unrealistic result will be obtained if a fracture process including unstable cracking is simulated by the quasi-static procedure.

Numerical investigation of crack growth in concrete subjected to compression by the generalized beam lattice model

“…As for concrete, the beam lattice model allows for a straightforward implementation of the heterogeneity of the three-phase system: aggregate, matrix and interface between them [21,[25][26][27][28]34,35,40]. There are arguments on the inclusion of elemental bending deformations.…”

“…This instability disappears naturally in beam lattices. The GB lattice model was recently developed by [26][27][28] and is also a kind of beam lattices. All investigations in this paper are based on the GB lattice model.…”

“…The former can obtain more realistic results than the latter, but leads to a substantial increase of the computational effort [2,40]. To solve the problem of computational effort, the generalized beam (GB) lattice model was developed by [26][27][28]. The key idea of GB lattice is the proposal of a kind of two-node and three-segment element.…”

“…When the computational effort is not the choke point, GB lattice model can also simulate the geometry of aggregates more accurately than the classical beam lattice [28]. In this paper, in order to obtain more detailed crack growth, numerical simulations are mainly conducted based on the GB lattice model proposed in [28] where every big aggregate is simulated by dozens of nodes, and only one compressive example is done based on the lattice proposed in [26,27] where every aggregate is represented by only one node.…”

“…In this model proposed by [26][27][28], a kind of two-node and three-phase elements has been developed. Every element is composed of three beams, which can be aggregate-phase, matrix-phase or interface-phase independently (Fig.…”