Corrosion induced losses in pre-stressed tendons

O'FLAHERTY, Fin, ELOMARI, Ibrahim and LAMBERT, Paul (2017). Corrosion induced losses in pre-stressed tendons. In: 37th Cement and Concrete Science Conference, University College London, 11-12 September 2017. (Unpublished)

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Abstract

The diameter of single tendons in pre-stressed concrete is typically around 5mm, corrosion combined with high levels of pre­stress can lead to a catastrophic, sudden rupture if not discovered in time. However, even if corrosion is present but not severe enough to cause rupture, a loss in pre-stress may result which may influence the load carrying capacity of the member This paper investigates the loss in pre-stress of tendons subjected to different levels of corrosion and different level of pre-stress. Twelve timber moulds were manufactured as a base for applying the pre-stressing technique. Ungalvanised tendons measuring 5.4mm diameter were pre-loaded to two extreme target levels of stress, namely 30% and 80% of ultimate tensile strength (UTS) and surrounded by mortar. Accelerated corrosion of 0% (control), 3% and 6% target loss of cross-sectional area were applied to replicate in-situ conditions. The strain in the tendons was continuously monitored throughout the corrosion process via vibrating wire strain gauges. The results show that the lightly pre-stressed tendon (30% UTS) exhibited a negligible change in pre-stress for 0% and 3% corrosion which increased to 17MPa when the degree of corrosion was doubled to 6%. Similarly, a decline in the initial high target level of pre-stress of 80% UTS was recorded as 9 MPa for 3% corrosion but when the corrosion doubled to 6%, the loss in pre-stress increased by a factor of 7 to 63MPa reduction. This indicates that higher degrees corrosion coupled with higher levels of pre-stress leads to higher losses of pre-stress and this should be accounted for as an additional loss at the design stage.

Item Type:	Conference or Workshop Item (Paper)
Research Institute, Centre or Group - Does NOT include content added after October 2018:	Materials and Engineering Research Institute > Structural Materials and Integrity Research Centre > Centre for Infrastructure Management
Departments - Does NOT include content added after October 2018:	Faculty of Science, Technology and Arts > Department of Engineering and Mathematics
Depositing User:	Fin O'Flaherty
Date Deposited:	30 Jan 2018 16:40
Last Modified:	18 Mar 2021 15:32
URI:	https://shura.shu.ac.uk/id/eprint/16672

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