Finite Element Analysis of WWCB WALL Panel Flexural Behaviour

In the present work, the finite element method is applied to understand the load–deflection response of Wood Wool Cement Board (WWCB) wall panel. The WWCB wall panel was modelled using ANSYS finite element software with 8-noded SOLID65 and SOLID45 Element. The same parameters as the experimental data were used to model the wall panel in FEA. Characteristic points on the load-deflection response curve predicted using finite element analysis (FEA) were compared to experimental data. The comparison shows that the ANSYS finite element program is capable of modelling and predicting the actual deformation behaviour for wall panels. Conclusions were then made as to the accuracy of using finite element modelling for analysis of WWCB wall panel. Keywords— ANSYS; WWCB; load-deflection; Finite element analysis.


I. INTRODUCTION
The use of FEA has been the preferred method to study the behaviour of WWCB wall panel for economic reasons. By understanding the use of finite element method, more efficient and better analysis can be made to fully understand the response of individual structural components and their contribution to a structure as a whole. Monique and Harry (2002) contained a paper concerning FEA of wood frame shear walls. They evaluated the effect of vertical load on the static and cyclic behaviour of the wood frame shear walls and their results shown good correlation between FEA and experimental data. Tavio and Tata (2009) developed a nonlinear finite element modelling of rectangular normal strength reinforced concrete columns under axial compressive loading. Their results indicate that the stressstrain relationships obtained from the analytical model using ANSYS are in good agreement with the experimental data.
Aainaa (2008) proposed a method to determine the ultimate load of the WWCB wall panel and type of failure occurred using experimental works. The experimental ultimate load determined was 83.3KN. The FEA calibration study included modelling a wall panel with the dimension and properties corresponding to WWCB wall panel tested by Aainaa (2008).
The objective of this paper was to investigate and evaluate the use of the finite element method for the analysis of WWCB wall panel. First, a thesis (Aainaa 2008) was conducted to evaluate experimental and analytical procedures related to WWCB components. Second, a calibration model using a commercial finite element analysis (ANSYS) was set up and evaluates using experimental data.

II. FINITE ELEMENT ANALYSIS
One of the suitable software that can be utilized to describe the actual failure behaviour of WWCB wall panel is ANSYS. To create the finite element model in ANSYS there are multiple tasks that have to be completed for the model to run properly.

A. Element Type
The SOLID65 element was used to model the wall panel. This element has eight nodes with three degrees of freedom at each node translations in the nodal x, y and z direction. This element is capable of plastic deformation, cracking in three orthogonal directions and crushing. A SOLID45 element was used for steel plate at the supports for the wall panel. This element has eight nodes with three degrees of freedoms at each node. The geometry and node locations for SOLID65 and SOLID45 elements are shown in figure 1.

B. Material Properties and Model
The SOLID65 element requires linear isotropic and multilinear isotropic material properties to properly model the panel. The multilinear isotopic material uses the von Mises failure criterion along with the Willam and warnke (1974) model to define the failure of the concrete. The modulus of elasticity of the WWCB is 2700MPa and the Poisson's ratio is 0.3. The compressive uniaxial stress-strain relationship for the model was obtained from Werasak and Meng (2008) model for light weight concrete used in ANSYS. The SOLID45 element is being used for the steel plates at loading point and supports on the panel. Therefore, this element is modelled as a linear isotropic element with a modulus of elasticity 210GPa and Poisson's ratio 0.3.
The panel, plate and supports were modelled as volumes.

C. Load and Boundary Conditions
Displacement boundary conditions are needed to constrain the model to get a unique solution. To ensure that the model acts as same as the experimental wall, boundary conditions need to be applied at points of symmetry, and where the supports and loading exist. The support was modelled in such a way that the roller and hinge were created. The ultimate load from experimental data is applied at the steel plate across the entire centreline of the plate. Figure 3 illustrates the panel and applied loading.

RESULTS
The finite element analysis of the model was set up to examine the behaviour of cracking and strength limit state of the panel. The Newton-Raphson method of analysis was used to compute the nonlinear response.