Operational modal analysis of a self-supporting antenna mast

This paper presents the results of an operational modal analysis on a self-supporting antenna mast. The structure is instrumented with seismic accelerometers, which are moved in different setups for detailed characterization mode shapes. In addition, eight strain gauges installed, two at bottom each leg tower. Two particular challenges highlighted. First, due to symmetry tower, bending modes occur pairs near identical natural frequencies and orthogonal These shapes change from one setup another, complicates merging partial obtained setups. Second, acceleration signals polluted by radio signals. It shown how these issues solved, resulting identification five modes. identified very close those predicted finite element model where vertical columns modeled using beam elements connections between braces assumed pinned. confirms validity such models assessment dynamic response lattice towers under wind loading.