Comparison of Static and Long-term Creep Behaviors between Balau Wood and Glass Fiber Reinforced Polymer Composite for Cross-arm Application

Cross arms are mainly made up of wood (conventional) and pultruded glass fiber reinforced polymer composite (modern) installed in suspension tower. However, the creep response of both materials has not been fully covered in many literatures to explain the long-term durability of the current cross arm design. Thus, it is necessary to find the creep trends and models to evaluate the behavior in the tropical outdoor environment. The creep properties of Balau wood and pultruded composite at load of 10, 20 and 30 % of ultimate flexural stress were evaluated from quasi-static flexural test results. Using several creep numerical models, the creep properties of wood and composite cross arms were modelled. The results showed that the GFRP had a significant value of flexural strength, while Balau wood performed better in flexural modulus. In terms of creep properties, GFRP specimen exhibited high creep resistance with greater stability during transition from elastic to viscoelastic phase. From numerical modelling perspective, the simulated creep trends from Burger and Norton models were deviated from the experimental data. Subsequently, the most suitable creep model to forecast the creep behavior for wood and composite specimens was Findley model. All in all, pultruded composite is the most appropriate durable material to be applied in cross arms, while Findley model is a suitable model to represent creep performance of anisotropic materials.