Impact of random field-Size effect using Turning Band Method (TBM) on damage behavior modelling of oil palm shell concrete under compression test

As a non-homogenous material, the characteristic tests of concrete in the laboratory do not always represent the quality and the size of the actual condition in the construction field. The heterogenous characters have an essential role that evokes the variability of concrete properties. In a case requiring high accuracy, such as concrete damage or crack modelling, heterogeneities should be considered. The objective of this research is to apply the variability of mechanical properties to numerical simulation in a simple cubical sample of Oil Palm Shell (OPS) concrete. By using a statistical approach, the variability is captured by a random field, in which its random variables are generated by implementing The Turning Band Method (TBM) in a finite element code-based application, Cast3M. Mazars damage model is chosen to govern the concrete damage behavior. The simulation is performed by varying a random field meshing size and correlation length, and the sample is compressively loaded. The modelling results are compared to the previous laboratory test conditions. By considering the concrete heterogenous nature, the damage pattern is varied, in which the modelling using smaller mesh exhibited a failure that was relatively close to the experimental study. The damage behavior of finer mesh showed more variation with the cracks accumulated in certain parts of the sample's sides, whereas it is dominantly spread on the whole top section in coarser mesh. Moreover, the modification of the mesh dimension and correlation length indicated that it has considerable effect on the concrete damage behavior and strength estimation.