Effect of dynamic wind force on structures using spectral approaches with complex modal analysis

The dynamic wind loads are considered in terms of equivalent static wind load based on gusteffect factor in most of the current design practices. In ASCE 7-05, the equivalent static wind load is based on the gust-effect factor f G which corresponds with the displacement at the highest point of the structure for flexible or dynamically sensitive structures. Gust-effect factors are calculated directly from background and resonance response by spectral method using their real modal properties. The main focus of the present investigation is on the influence of nonproportional viscoelastic damping matrix (for independent-frequency case system) and symmetrical stiffness and damping matrices (frequency-dependent case system) on the spectral calculation. A new transfer function is introduced in complex modal analysis or spectral stochastic response analysis. The case study is clearly demonstrated with numerical calculations showing the accuracy and high performance in this method.