Engineering bond model for corroded reinforcement

Abstract

Corrosion of the reinforcement in concrete structures affects their structural capacity. This problem affects many existing concrete bridges and climate change is expected to worsen the situation in future. At the same time, assessment engineers lack simple and reliable calculation methods for assessing the structural capacity of structures damaged by corrosion. This paper further develops an existing model for assessing the anchorage capacity of corroded reinforcement. The new version is based on the local bond stress-slip relationships from fib Model Code 2010 and has been modified to account for corrosion. The model is verified against a database containing the results from nearly 500 bond tests and by comparison with an empirical model from the literature. The results show that the inherent scatter among bond tests is large, even within groups of similar confinement and corrosion level. Nevertheless, the assessment model that has been developed can represent the degradation of anchorage capacity due to corrosion reasonably well. This new development of the model is shown to represent the experimental data better than the previous version; it yields similar results to an empirical model in the literature. In contrast to many empirical models, the model developed here represents physical behaviour and shows the full local bond stress-slip relationship. Using this assessment model will increase the ability of professional engineers to estimate the anchorage capacity of corroded concrete structures.

Partial safety factors for the anchorage capacity of corroded reinforcement bars in concrete

“…The ARC2010 model for calculating the anchorage capacity of corroded reinforcement bars is described in detail in [15]. The essence of the model is presented, because it is necessary to understand the calibration of partial factors presented later.…”

“…The local bond stress is defined by the local bond stress-slip relation, which for the uncorroded case is obtained from fib Model Code 2010 [19]. For corroded cases, the local bond stress-slip relation proposed in [15] is used instead. It is based on the fib Model Code 2010, but includes three modified and additional elements to account for the effect of corrosion:…”

“…The concept of equivalent slip is presented in Figure 2. The equivalent slips for cases with and without stirrups were calibrated against a large database of bond tests in [15], resulting in: where is the corrosion weight loss in decimals and , is the equivalent slip in mm. The corrosion domains for the model are 0-15% and 0-20% for cases without and with stirrups respectively.…”

“…The corrosion domains for the model are 0-15% and 0-20% for cases without and with stirrups respectively. These are based on the validation of the model presented in [15].…”

“…Bond in general and bond of corroded reinforcement in particular have been studied in several research projects, see [11,12,13,14] for example. A simple assessment model for bond of corroded reinforcement has been developed [15] to make the results accessible and relevant to society. It is called ARC2010, with professional engineers as its intended users.…”