Nonlinear dynamic behaviour of saddle shaped cable nets under wind action

The nonlinear dynamic behaviour of saddle shaped cable nets, subjected to wind actions, is studied in this work. Time-history analyses are performed, considering the geometric nonlinearity of the system. The maximum dynamic response, expressed by means of the maximum nodal amplitude and cable tension, is compared with the response provided by quasi static analysis methods, proposed by Eurocode 1. Although the main frequencies of the wind load are smaller than the eigenfrequencies of the system, they cause significant response amplitudes, verifying the occurrence of superharmonic resonances. In addition, small amplitudes of the wind load, with frequencies close to the eigenfrequencies, induce large oscillation amplitudes due to fundamental resonances, despite the existence of damping. The quasi static methods cannot predict such nonlinear dynamic phenomena, leading to unsafe results.