Analysis of pole-type structures of fibre-reinforced plastics by finite element method.

摘要

Fibre-reinforced plastics (FRP) are becoming increasingly popular in the engineering applications as alternative to conventional engineering materials. The unique characteristics of FRP, such as their light weight, their resistance to corrosion, and the lower cost of construction and maintenance, are very promising in the application of FRP in civil engineering. One such application is the replacement of power transmission poles, traditionally made of either concrete, steel, or wood, by FRP poles.; This thesis deals with the finite element analysis of fiber-reinforced plastic poles. Using the principle of stationary potential energy and Novozhilov's derivations of nonlinear strains, tapered FRP poles are treated as conical shells and a semi-analytical finite element model based on the theory of shell of revolution is developed. The computer program based on the finite element model developed can be used to perform: (a) a linear static analysis, (b) a linear buckling (bifurcation) analysis, (c) a linear scP {dollar}- Delta{dollar} analysis, (d) a geometrically nonlinear (large deflection) analysis of beam-column-type bending, and (e) an ovalization analysis.; Solution methods of the nonlinear system of equations are discussed. Based on the augmented equation method, external and internal potential control schemes are proposed and evolved into incremental work control and incremental strain energy control. These controls are proven to have good capability to traverse a limit point.; For slender poles, the nonlinear behaviour of beam-column type bending is more important. This type of nonlinear analysis requires the proper handling of the rigid-body rotation. A method is proposed to include the rigid-body model in the analysis.; The ovalization of cylindrical poles is investigated numerically. The analysis involves the inclusion of all second-order Fourier terms in the displacement functions. It is demonstrated in this thesis that ovalization can significantly decrease the load carrying capacities of cylindrical poles. The linear stability and the scP {dollar}- Delta{dollar} analyses are considered to be simplifications of the nonlinear analysis of beam-column type bending. Assumptions and conditions which enable the simplifications are also discussed. The linear analysis is the simplest analysis and is applicable for small displacements. Behaviors of FRP poles with different material configurations, geometries, loading and boundary conditions are investigated using the linear analysis. The numerical results from the proposed analyses are compared with limited experimental data and with analytical results.