Finite Element Analysis of the Seismic Behavior of Guyed Masts

Seismic design of guyed masts, commonly used in the broadcasting and telecommunications industries, has not been fully addressed in the United States. There is no specific design code, and only a limited amount of research has been reported on the subject. This research investigates the behavior of guyed masts incorporating synthetic ropes as guys, with a particular focus on the effect of snap loads on the mast behavior. This is the third phase of a multi-stage project aimed at analyzing the potential for Snapping-Cable Energy Dissipators (SCEDs) to minimize lateral response in structures.

A finite element model of a 120-m-tall guyed mast was developed with the commercial program ABAQUS. The three-dimensional behavior of the mast was observed when subjected to two ground motion records: Northridge and El Centro. Three orthogonal earthquake components were input, two horizontal and one vertical. A series of parametric studies was conducted to determine the sensitivity of the response to guy pretension, which is a measure of the potential slackness in the guys during response. Additionally, the studies examined the effects of guy stiffness, mast properties, and directionality of input motion.

Deflections, bending moments, guy tensions, and base shears were examined. The results were used to characterize the trends in the structural response of guyed masts. The level of slackness in the guys changed the behavior, and the lessons learned will be used to continue research on the application of SCEDs in structures.