The effect of semi-rigid connections on the dynamic behavior of tapered composite GFRP poles

This paper deals with the dynamic behavior of tapered composite poles with circular hollow cross-section and flexible connections, which are designed for use in power transmission lines. These poles, made from polyester reinforced with E-glass fibers, are produced using the filament winding technique. Transmission poles are mainly subjected to cantilever bending, since loading due to the wires and wind gusts is applied laterally. In the present work, a simple, but reliable, tapered beam element is developed and the dynamic behavior of the poles is accurately captured using only a few elements. A simple model for flexible connections is established and incorporated in the analysis. The material is orthotropic and its behavior is assumed linearly elastic. Shear effects are accounted for in the analysis because of their significant role due to the low shear modulus. Modal analysis is performed for design purposes to obtain the natural frequency and period of poles with various geometrical characteristics and material lay-up, as well as the effect of connection flexibility. Experimental results on the dynamic behavior of jointed composite poles are also presented and the effect of damping is estimated. The analytical results presented in this work are based on typical composite poles produced by filament winding, and are compared to commercially available finite element codes.