Influence of size on the constitutive equations of concrete or rock dowels

Abstract

The numerical fracture analysis of non-homogeneous rock or concrete dowels subjected to shear and compression is described in detail. The method of analysis allows the consideration of scale and rate effects due to material non-homogeneity and fracture. The proposed approach is verified by comparing numerical predictions with experimental results reported in the literature for a series of small rock samples, since experimental evidence for large bodies is not yet available (2007). Results generated by Monte Carlo simulation using the so-called discrete element method to model the dowels suggest that a simple three parameters law can be used to predict the relationship between tangential stress at the base and lateral distortion. It is observed that the larger the size of the cubes, the smaller both the peak tangential stress and the rupture distortion. Size effects are also evaluated in samples with vertical restraint. The influence of loading rate is likewise numerically assessed for two sample sizes. The effect is compatible with experimental evidence available for concrete using small samples.

Crack propagation in elastic solids using the truss-like discrete element method

“…More detail about the calibration model could be founded in Kosteski et al (2011). As it was demonstrated in Miguel et al (2008) when we have a strong localization, as in the present case, the results are independent of the level of discretization (for element length less than one tenth part of the main crack length). As is showed in Sects.…”

“…Riera and other researchers have been carrying out several applications of DEM to model shells subjected to impulsive loading (Riera andIturrioz 1995, 1998); fracture of elastic foundations on soft sand beds (Schnaid et al 2004); dynamic fracture (Miguel et al 2010); generation and spread of earthquakes (Dalguer et al 2001); scale effect in concrete (Rios and Riera 2004) and in rock dowels (Miguel et al 2008 andIturrioz et al 2009). …”

A lattice discrete element method to model the falling-weight impact test of PMMA specimens

“…Rocha et al [30], and more recently Kosteski et al [16], extended the LDEM to account for to the irreversible effects of crack nucleation and propagation. Since then, the method have found applications in the analysis of impulsive loads in shells [28], fracture of elastic foundations on soft sand beds [32], scale effects in concrete [29] and rocks dowels [13,21] and fracture and damage propagation [16,18,22].…”

Caracterização Do Processo De Fratura Utilizando O Método Dos Elementos Discretos E as Técnicas De Emissão Acústica

“…A aplicação do DEM para o estudo de problemas de engenharia pode ser verificada nos seguintes trabalhos: Problemas dinâmicos de cascas sujeitos à carga impulsiva, Riera e Iturrioz, 1995 e 1998, estudo da fratura em fundações elásticas apoiadas sobre solos brandos Schnaid et al 2004, simulação da geração e posterior propagação de sismos, Dalguer et al, 2001, estudo do efeito de escala em concreto e rochas, Rios e Riera, 2004, Miguel et al, 2008e Iturrioz et al, 2009, medição de parâmetros fractomecâni-cos, Kosteski et al, 2009, entre outros. Entre os trabalhos relacionados diretamente com o estudo da microestrutura de materiais compostos é possível citar Batista, 2007, e Kosteski et al 2012, que analisaram com DEM a microestrutura de ferro fundido nodular. E relacionados com técnicas de emissão acústica se podem citar Iturrioz 2013a,b. O Método dos Elementos Discretos utilizado no presente trabalho é formado por módulos cúbicos, como se mostra na Figura 1.…”

“…Isto é, contudo, uma limitação importante, inicialmente abordada por Rios e Riera (2004). Mais tarde, Miguel et al (2008) adotou o método proposto por Shinozuka e Deodatis (1996) para simular um campo aleatório gaussiano 3D para modelar a propriedade do material de interesse. A técnica mais simples foi empregada por Puglia et al (2010).…”