Bolt evaluation in ANSYS
Structural calculations are our every day business. The evaluation of the structural components is straight forward. Problems arise, when the components are connected by bolts. If the number of connections is high, they cannot be modelled in detail but have to be simplified. The nonlinear behaviour of the connected Paris has to be considered to receive a realistic force within the individual bolts. The crucial point is the evaluation of the resulting working load and the comparison to the rules and standards.
VDI 2230 and Eurocode 1993-1-8 with FEM
Bolts under pretension being exposed to dynamic loads are usually evaluated in accordance to the VDI 2230. Bolted connections in steelwork constructions transfer shear forces by bearing stress and can therefore be evaluated according to the Eurocode 1993-1-8. For the evaluation of standard framework connections by Eurocode 1993-1-8 we use the software RSTAB. If the connection cannot be classified as standard, we calculate the load distribution though the bolts by FEM simulation. Then, the bolts are evaluated analytically by Eurocode 1993-1-8. The advantage of this procedure is that the utilization of each bolt can be determined individually.
Test case scenario
In the specific case, the bolted connection of a corner joint of a frame was examined. A special feature of the design was an angular connection, which creates additional moments on the bolted connection.
The connection was modelled with ANSYS Workbench 19. The bolts were modelled after the VDI guideline 2230, model class III, as volume without thread. This model class offers a very good balance between modelled effort and realistic representation and enables a detailed stress evaluation in the flange. The pretension of the bolts was considered as well as the frictional contact between the bolts and the frame.
The evaluation was carried out analytically for every bolt in accordance with Eurocode 1993-1-8.