**4.1. Modelling concrete and grout**

Care was taken to develop the best model for concrete and grout that could offer appropriate behaviour. 3D solid elements, Solid 65 that has 8 nodes was used with each node having three translation degrees of freedom that tolerates irregular shapes without a significant loss in accuracy. Solid 65 is used for the 3-D modeling of solids with or without reinforcing bars (rebar). The geometry and node locations for this type of element are shown in Figure 5 a. The solid element is capable of plastic deformation, cracking in tension, crushing in compression, creep non-linearity, and large deflection geometrical non-linearity, and also includes the failure criteria of concrete Fanning (2001), Feng et al. (2002) and Ansys (2012). Concrete can fail by cracking when the tensile stress exceeds the tensile strength, or by crushing when the compressive stress exceeds the compressive strength. A FE mesh for concrete is shown in Figure 5 b. Figure 6 shows the FE mesh for grout. Due to symmetry only a quarter of the model needed to be treated.
