Date of Award
Doctor of Philosophy
The dynamic response of guyed masts excited by wind turbulence is examined in this study using numerical methods. Specifically, the report addresses two main subject areas: the development of a simplified dynamic analysis method for guyed masts, and an investigation of the nonlinear dynamic response characteristics of guys and guyed masts.;A simplified patch load analysis method is proposed which reliably estimates the dynamic response of a wide variety of guyed masts. A series of static load patterns, or patch loads, are used to replicate the effects of wind gusts. Empirical scaling factors account for mast geometry and structural properties.;The proposed patch load method was calibrated against dynamic analyses of eight existing masts. For this portion of the study, dynamic analyses were performed with a frequency domain analysis model which utilized linear spring-mass guy representations.;Nonlinear dynamic response was studied in the time domain using a step-by-step integration procedure to solve the governing equations of motion. Numerically simulated turbulent wind fields were generated using a second-order autoregressive process.;The first stage in the nonlinear study considered the response of guys excited by enforced horizontal displacements at their upper ends. For harmonic enforced displacements, nonlinear coupling between response at the forcing frequency and its harmonics was found to suppress the resonant response by diffusing the resonant energy; however, nonlinear coupling also led to significant subharmonic resonance at critical forcing frequencies. Nonlinear coupling effects appeared to be at least partially disrupted when the enforced displacements time histories were random in nature. In all cases, linear spring-mass guy models tended to overestimate the nonlinear resonant response. While mean wind acting on the guys affected the guy tension and resulted in significant aerodynamic damping, fluctuating wind forces had a negligible effect on guy reaction forces.;Nonlinear time domain studies of a guyed mast indicated that acrosswind response contributes significantly to peak dynamic bending moments in the mast; peak mast deflections and shear forces were found to be less sensitive to acrosswind motion. In general, acceptable agreement was obtained between fully nonlinear models and models using simplified spring-mass guy representations.
Sparling, Bruce F., "The Dynamic Behavior Of Guys And Guyed Masts In Turbulent Winds" (1995). Digitized Theses. 2576.