Keywords: nonlinear analysis, camera pole, fibre reinforced polymer, finite element, solid element.

This paper presents an experimental and finite element model (FEM) investigations of the load-deflection characteristics of tapered hollow fibre reinforced polymer (FRP) poles subjected to a cantilever bending loading. Two full-scale experimental tests have been conducted on tapered circular cross section FRP poles to identify their load deflection characteristics [1,2]. FRP poles were tested in the laboratory by welding each pole to an end-plate, which was bolted to a concrete block. The concrete block was bolted to the laboratory reaction floor by means of threaded rods that were placed in the forms before casting the concrete. This introduced the actual field condition for installed closed circuit television camera poles.

A three-dimensional nonlinear finite element model is generated using the finite element analysis (FEA) software package, ANSYS version 9.0. The three-dimensional FEA of the entire pole and its connection assembly was introduced by taking advantage of the plane of symmetry. Three dimensional isoparametric elements were used to model the pole, end-plate, bolt and concrete base. A bilinear stress strain relationship was used for the pole, end-plate and the bolt. The complex interaction between the surfaces of end-plate and concrete base and the surfaces around the bolt were modelled with the three-dimensional eight-noded surface-to-surface contact and target elements. The effect of plasticity and the pretensioning of the bolt were also included in the model. Pretension effect of the bolt was modelled with the three-dimensional pretension elements [3,4]. The three-dimensional finite element model uses the bilinear isotropic hardening option in ANSYS. The bilinear isotropic hardening uses the Von Mises yield criteria coupled with an isotropic work hardening assumption. This option is often preferred for large strain analyses.

The results obtained from the FEA for the load-deflection curves were compared with those from experiments, which showed that the FEM predicted the poles' behaviour closely with maximum error of 2.2%. The accuracy of the FEM was the result of the detailed modelling of the actual geometry of all the structural components in the pole as prescribed by the experiments setup and the AISC specifications. Special attention was given to the level and location of the mesh refinement that contributed to the excellent agreement between the experimental and the FEA results obtained. To further verify the FEA, a parametric study was conducted by varying pole's geometric variables one at the time while keeping other variables constant. The obtained load-deflection results showed that FEA produced the expected and the intuitive results.

1

D. Polyzois, S. Ibrahim, I.G. Raftoyiannis, "Performance of fibre-reinforced plastic tapered poles under lateral loading", Journal of Composites Materials, 33(10), 941-960, 1999.

2

Z.M. Lin, "Analysis of pole-type structures of fibre-reinforced plastics by finite element method", Ph.D. Dissertation, University of Manitoba, Canada, 1995.

3

A.M. Citipitioglu, R.M. Haj-Ali, D.W. White, "Refined 3D finite element modelling of partially-restrained connections including slip", J. of constructional Steel Research, 58, 995-1013, 2002. doi:10.1016/S0143-974X(01)00087-6

4

N. Kishi, A. Ahmed, N. Yabuki, "Nonlinear finite element analysis of top- and seat-angle with double web-angle connections", Structural Engineering and Mechanics, 12(2), 201-214, 2001.

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