Numerical modelling for rain wind induced vibration of cables with longitudinal ribs

Abstract

Aerodynamic countermeasures are among the most effective ways to mitigate rain-wind induced vibrations. However, their vibration control mechanism is in many cases still unclear. This paper presents a numerical model for a cable section with an arbitrary 2D shape, able to geometrically describe aerodynamic countermeasures, excited by both wind and rain. Based on lubrication and vibration theory, 2D coupled equations for the water film evolution and for the across wind cable vibration are derived. Wind pressure and friction coefficients, for the different evolving water-film morphologies, are calculated by CFD software, while the instantaneous water film distribution and the vibration of the cable are calculated by numerically solving the derived coupled equations. For the case of rib additions to a nominally circular cable, the model shows that there is direct impact on the formation and dynamic characteristics of the critical for rain-wind induced vibrations upper rivulet. Particularly, depending on the rib number and position(s), the countermeasure can become effective or not by altering the aeroelastic lift acting upon the cable, and redistributing its frequency content associated with instability phenomena.

Mitigation mechanism of longitudinal ribs on rain-wind induced vibrations of stay cables

“…Equations (1) and (3) are the main coupled equations for the water film evolution and the stay cable vibration. The derivation process is shown in detail by Bi et al (2018).…”

“…Equations (1) and (3) are solved by a finite difference scheme through the numerical software platform of MATLAB. The calculation process uses the same details as previously reported in Bi et al (2018).…”

Design of flexible sensor for wind pressure monitoring of stay cables

“…Li et al used numerical simulation to analyze the parametric vibration of cable-stayed bridges [18]. Bi et al also used numerical simulation to calculate the instantaneous wind pressure distribution and vibration of cable-stayed bridges by numerically solving the coupled equations [19]. Numerical simulation methods do not require excessive manpower and complex equipment, but the simulation results are ideal and it is difficult to simulate the wind field in real environments [20][21][22][23].…”