Nonlinear dynamic analysis of prestressed cable structure under random aerodynamic loading

Resumo

Abstract. This paper includes the development and dynamic analysis of a mathematical model of an elastic prestressed cable structure such as those used in light roof structures known as tensile structures in which the external loads are balanced by tensile forces in the cables. Due to the light weight of this structural model the aerodynamic loads are critical and determine the design.
The model consists of four same length and section cables arranged in an X-shape in a planar view, fixed at one end, with an equivalent mass of the system in the center node, their other extremity. The cables are not in a plane: two opposite cables have their supports in the same positive vertical height, and the other two opposite cables have their support in the same negative vertical height.
There are forces acting on the central node in the x, y and z directions modeling random aerodynamic loading simulated by a Monte Carlo-type procedure inspired by Prof. Francos Synthetic Wind Method. This technique involves creating several loading series combining different harmonic components with amplitudes and frequencies obtained from an adopted PSD (Power Spectrum Density Function) with randomly chosen phases. This results a large number of response displacements and tensions to be statistically treated to render sound engineering design decisions.
The model admits large displacements so that a nonlinear dynamic approach is adopted. A numerical step-by-step finite differences time integration scheme is also implemented.