Andrea Freda

Uncertainties in the evaluation of one degree-of-freedom galloping onset

This study discusses the uncertainties inherent in the galloping onset conditions of wind-excited structural elements using error propagation techniques. The problem is dealt with considering two different technical situations: the estimate of the critical wind velocity for engineering applications and the assessment of the galloping factor derived from wind tunnel experiments over a specific structural element. In the former case, significant errors may arise from the scattering of the whole set of involved parameters. In the latter case, it is shown that the galloping factor obtained in the wind tunnel test is a random variable, unavoidably affected by uncertainties due to measuring errors and its estimation technique. In both cases, it is shown that the classic deterministic approach based on nominal values of the parameters may lead to unsafe estimations of the one degree-of-freedom galloping onset.

Wind - Induced Instability of Complex Lighting Poles and Antennas Masts: Static and Aeroelastic Experimental Study

In a previous paper authors studied the aeroelastic behavior of complex lighting poles and antennas masts by carrying out static sectional model tests, determining aerodynamic coefficients and using them in the framework of quasi-steady theory. This paper continues the above research by illustrating the results of aeroelastic sectional model tests aimed at verifying the precision and reliability of the previous approach. The aeroelastic experiments are conducted by increasing and decreasing the mean wind velocity in order to check the presence of hysteresis phenomena.