Rehabilitation of Wooden Utility Poles with Sprayed-GFRP Composites
Publication: Journal of Composites for Construction
Volume 28, Issue 1
Abstract
Different rehabilitation techniques have been utilized to extend the service life of wooden utility poles, which are mainly affected by degradation and decay. This paper presents an evaluation of the performance of wooden utility poles rehabilitated using sprayed glass fiber–reinforced polymer (GFRP) composites and near-surface-mounted (NSM)-GFRP bars. Seven full-size (305-mm diameter) new wooden poles and five full-size old wooden poles, taken out of service, were tested under monotonically increasing lateral load. The test parameters included the thickness (4, 6, and 8 mm) and length (1.0 and 2.0 m) of the sprayed-GFRP coating, and rehabilitation methods (sprayed-GFRP composites, NSM-GFRP bars). The results showed that the sprayed-GFRP coating can restore the load-carrying capacity and enhance the stiffness of both old and damaged poles. In addition, the load-carrying capacity of the wooden poles was not affected by the increase in GFRP thickness after the thickness reached 6 mm. It was also concluded that using the NSM-GFRP bars is not cost-effective compared to the sprayed-GFRP composites. A simple analytical procedure was introduced to estimate the load-carrying capacity of retrofitted poles and to calculate the required thickness of the sprayed-FRP layer, which yielded reasonably conservative results.
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Data Availability Statement
All data, models, and codes generated or used during the study appear in the published article.
Acknowledgments
The authors would like to acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC) and Manitoba Hydro. The authors also acknowledge the in-kind contribution by Manitoba Hydro (providing the poles) and by Carlson Commercial & Industrial Services Ltd. (providing the sprayed-GFRP composites). The help received from the technical staff at the W.R. McQuade Structures Laboratory is also greatly appreciated.
Notation
The following symbols are used in this paper:
- a
- distance between the loading point and the top of the pole;
- C
- circumference of the pole at the groundline (or failure) section;
- CN
- circumference of the pole at the notched section;
- F
- maximum fiber stress on the pole at groundline (or failure) section;
- Fmodified
- modified load requirements;
- Foriginal
- original horizontal load requirements from CSA O15-15 (CSA 2019);
- fu,FRP
- ultimate tensile strength of the sprayed-FRP coupons;
- h
- height of the concrete base;
- L
- distance between groundline (or failure) section and point of load application;
- Lcut
- length of the cut pole;
- Lembed
- embedment length of the pole into the ground in practice;
- LN
- distance between the notched section and point of load application;
- Loriginal
- original length of the wooden pole;
- P
- lateral load capacity of the pole;
- Pest
- estimated load capacity of the pole;
- Pexp
- experimental failure load of the pole;
- Pf
- factored lateral load applied on the retrofitted pole;
- PFRP
- lateral load capacity of the sprayed-GFRP layer;
- Po
- lateral load capacity assuming a new pole;
- PN
- load capacity of the pole at the notched section;
- PN,FRP
- lateral load capacity of the sprayed-GFRP layer at the notched section;
- R
- radius of the pole at the groundline section;
- RN
- radius of the pole at the notched section;
- tFRP
- thickness of the sprayed-GFRP layer;
- ΔL
- longitudinal deflection of the load point at the maximum load; and
- ϕFRP
- material resistance factor of the sprayed-FRP.
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Published In
Journal of Composites for Construction
Volume 28 • Issue 1 • February 2024
Copyright
© 2023 American Society of Civil Engineers.
History
Received: May 7, 2023
Accepted: Oct 30, 2023
Published online: Dec 11, 2023
Published in print: Feb 1, 2024
Discussion open until: May 11, 2024
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