Structural assessment of current steel design models for transmission and telecommunication towers

Structural assessment of a lattice tower for a small, multi-bladed wind turbine

“…This can be a single bolted or multiple bolted angle, or a welded connection using a gusset plate. A degree of bending moments and possibly twist are therefore present at the connections [7,21]. Kroeker [20] investigated the secondary effects of modelling the connections as rigid instead of pinned and found that the secondary effects may lead to premature failure of electricity transmission towers.…”

“…During the FE solution phase, this will cause rigid body motion and the numerical solution will fail to converge. This fact is highlighted in [20] and [21]. This issue has most influence on dynamic analyses such as in a modal analysis, which is used to determine the natural frequencies of the structure.…”

“…This issue has most influence on dynamic analyses such as in a modal analysis, which is used to determine the natural frequencies of the structure. Modelling with truss elements means that the analytical structure has more dynamic degrees of freedom than in the actual case [21][22][23][24]. Two possible solutions to overcome this problem are to either use dummy members in the model to suppress the unwanted degrees of freedom or to replace the truss elements with beam elements.…”

“…Two possible solutions to overcome this problem are to either use dummy members in the model to suppress the unwanted degrees of freedom or to replace the truss elements with beam elements. The dummy members usually have a small axial stiffness which is large enough to eliminate any mechanisms that tend to form, while the use of beam elements retains the bending stiffness at the connections [21]. The work in [21] focused on the different results that can be obtained even using linear analysis by just changing the element types.…”

“…The dummy members usually have a small axial stiffness which is large enough to eliminate any mechanisms that tend to form, while the use of beam elements retains the bending stiffness at the connections [21]. The work in [21] focused on the different results that can be obtained even using linear analysis by just changing the element types. The lattice tower was modelled using either a model made up of solely beam elements or using a model made up of combined beam and truss elements.…”