Variation of damping and stiffness of lattice towers with load level

Steel lattice structure design is often controlled by dynamic loads such as wind, earthquake or shocks resulting from broken components such as guy cables or conductors. In order to properly evaluate the response of these structures under this type of loads, it is necessary to model accurately the structure. However, there is a lack of data in the literature to guide the designer to select adequate assumptions for stiffness and damping. Also, if a variation of these characteristics with the level of load was observed experimentally, this variation has not been researched in detail.In order to provide additional data and guidance on the modeling techniques to be used for lattice structures, and specifically to evaluate the relation of stiffness and damping with the load level, an 8 m long section of a transmission line tower was erected, pulled at different levels of solicitation and left to vibrate freely after the load was suddenly released. Numerical modeling was also conducted and compared to the experimental results. In this study, engineers will find practical information on modeling techniques to be used for lattice structures.

► Study on the behavior of a lattice tower in free vibration.
► Evolution of damping and stiffness of a lattice tower as a function of load level.
► Modeling of lattice tower with finite element program.
► Proposition of modeling technique and damping values for different load levels.