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. 2021 Feb 19;13(4):620.
doi: 10.3390/polym13040620.

Utilization of Bracing Arms as Additional Reinforcement in Pultruded Glass Fiber-Reinforced Polymer Composite Cross-Arms: Creep Experimental and Numerical Analyses

Muhammad Rizal Muhammad Asyraf  1 , Mohamad Ridzwan Ishak  1   2   3 , Salit Mohd Sapuan  3   4 , Noorfaizal Yidris  1
Affiliations

Utilization of Bracing Arms as Additional Reinforcement in Pultruded Glass Fiber-Reinforced Polymer Composite Cross-Arms: Creep Experimental and Numerical Analyses

Muhammad Rizal Muhammad Asyraf et al. Polymers (Basel). .

Abstract

The application of pultruded glass fiber-reinforced polymer composites (PGFRPCs) as a replacement for conventional wooden cross-arms in transmission towers is relatively new. Although numerous studies have conducted creep tests on coupon-scale PGFRPC cross-arms, none had performed creep analyses on full-scale PGFRPC cross-arms under actual working load conditions. Thus, this work proposed to study the influence of an additional bracing system on the creep responses of PGFRPC cross-arms in a 132 kV transmission tower. The creep behaviors and responses of the main members in current and braced PGFRPC cross-arm designs were compared and evaluated in a transmission tower under actual working conditions. These PGFRPC cross-arms were subjected to actual working loads mimicking the actual weight of electrical cables and insulators for a duration of 1000 h. The cross-arms were installed on a custom test rig in an open area to simulate the actual environment of tropical climate conditions. Further creep analysis was performed by using Findley and Burger models on the basis of experimental data to link instantaneous and extended (transient and viscoelastic) creep strains. The addition of braced arms to the structure reduced the total strain of a cross-arm's main member beams and improved elastic and viscous moduli. The addition of bracing arms improved the structural integrity and stiffness of the cross-arm structure. The findings of this study suggested that the use of a bracing system in cross-arm structures could prolong the structures' service life and subsequently reduce maintenance effort and cost for long-term applications in transmission towers.

Keywords: Burger model; Findley’s power law model; bracing system; creep; cross-arm; pultruded gfrp.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flow chart of the research methodology.
Figure 2
Figure 2
Cross-arm configurations: (a) with additional bracing arms—braced design; and (b) without bracing arms—current design.
Figure 3
Figure 3
Positions of dial gauges under the cross-arm to measure creep strain pattern, in meters.
Figure 4
Figure 4
(a) Schematic diagram and (b) actual image of PGFRPC cross-arm used in the creep test rig.
Figure 5
Figure 5
Schematic diagram of cross-arm’s beam when exposed applied force at the end of the cross-arm structure.
Figure 6
Figure 6
Schematic diagram of physical Burger model.
Figure 7
Figure 7
Typical creep and Relaxation Burger Model [39].
Figure 8
Figure 8
Creep strain-time curves for current PGFRPC cross-arm for (a) left and (c) right; braced PGFRPC cross-arm for left (b) and right (d) main member.
Figure 8
Figure 8
Creep strain-time curves for current PGFRPC cross-arm for (a) left and (c) right; braced PGFRPC cross-arm for left (b) and right (d) main member.
Figure 9
Figure 9
A parameter for current and braced PGFRPC cross-arms: (a) right; (b) left main members.
Figure 10
Figure 10
Ee parameter for current and braced PGFRPC cross-arms: (a) right; (b) left main members.
Figure 11
Figure 11
ηk parameter for current and braced PGFRPC cross-arms: (a) right; (b) left main members.
See this image and copyright information in PMC

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