Parameterized and Adaptive Modelling of Mechanical Connections in Timber Frame Structures

This study investigates the global stiffness of a timer frame structure under wind loading using the finite element method by creating parameterized script files. Of key interest was the accuracy of the global stiffness determined from an adaptive 3D beam model in comparison to a 2D beam model and, the stiffness of a 3D beam model when subjected to different types of bracing in the presence of internal bracing provided by a lift shaft structure. Investigation of contact forces on the surfaces between the fastener and the timber at the connection was carried out and a design check for the specified bolts shear capacity done with respect to Eurocode 5. A 3D adaptive connection was created for a 2D frame model and the stiffness of the structure was studied. A comparison of the maximum displacement of the structure in the x direction, under the same wind loading, spring stiffness and boundary conditions, with a 2D beam structure without the adaptive connection initially showed a difference in the displacement. This implied that the rotational stiffness in the beam model was greater than that of the adaptive connection created. Therefore after altering the rotational stiffness of the beam model to achieve similar displacement as in the adaptive model, the rotational stiffness of the created connection was found to be 33.4 · 106Nm. The study also determined the contact forces generated at the surfaces between the fasteners and the timber using the finite element method to integrate over the surfaces and calculate the forces. The results were generated using the History Output in the step module. The only disadvantage of acquiring the contact forces was that, the contact surface simulation caused larger run times for the model to complete the time step. For the adaptive model it took 18 hours to complete each step. Further investigation into the stiffness of a 3D frame structure was conducted. The model of the 3D structure was created by a parameterized script which makes it easy to change input variables such as number of internal walls, geometry in x-z-plane, number of storeys, cross-sectional dimensions, material properties number of diagonals and location of diagonals. A variety of models with different conditions was analyzed. This showed that stiffness has a major impact on the magnitude of reaction forces and displacements