Seismic Performance of Flexural Reinforced Concrete Columns with Corroded Reinforcement

Abstract

This paper presents an experimental study carried out on eight full-scale uncorroded and corroded reinforced concrete columns that were subjected to simulated seismic loading to investigate the effects of reinforcement corrosion on the seismic behavior of columns that failed in flexure. The main variables are the corrosion levels of reinforcement and applied axial force ratios. The seismic performance of test specimens was assessed in terms of crack pattern, hysteretic response, yield displacement, lateral load resistance, drift capacity, displacement ductility, and energy dissipation capacity. The results highlighted that the corroded columns suffered a significant degradation of strength and lateral drift capacity as compared to uncorroded columns. In addition, it is noteworthy to observe that the failure mode of corroded columns switched from flexural failure to flexural-shear failure and sudden axial failure when they are highly corroded and subjected to high axial force. An empirical equation based on the maximum pit depth of corroded longitudinal reinforcing bars was proposed to predict the residual flexural strength of corroded columns. Furthermore, based on the shear strength model proposed in ASCE/SEI 41-13, methods were proposed to estimate the shear strength of corroded columns failed in flexural-shear failure and axial failure, which consider the contribution reductions to shear strength of transverse reinforcement and concrete due to corrosion. Among these methods, the shear strength of corroded columns estimated based on the corrosion mass loss and average residual cross-sectional area was not conservative as compared to the test results. In contrast, the shear strength of corroded columns predicted using the minimum residual cross-sectional area of transverse reinforcing bars showed good and reliable correlation with the experimental results.

Analytical modeling of corroded RC columns considering flexure-shear interaction for seismic performance assessment

“…Firstly, a selected column is simulated with two methods to show the importance of shear response consideration in modeling the seismic behavior of corroded columns. This column is C3 from the tests by Vu and Li (2018a). It was originally ductile-designed but failed in a non-ductile manner due to corrosion.…”

“…Recent studies (Li et al 2018;Vu and Li 2018a) have shown that the failure mode of ductile-designed columns could shift from flexural to shear if the transverse reinforcement was highly corroded. In fact, transverse reinforcement can corrode more severely in reality as the diameter is smaller and the distance to corrosive environment is closer compared with longitudinal reinforcement (Vu and Li 2018a). Thus, the shear capacity could deteriorate more significantly as compared with flexural capacity.…”

“…As a result, columns could fail in shear under cyclic loadings although they were originally designed to fail in flexure. For example, tests by Vu and Li (2018a) showed that a 25% corrosion level in transverse reinforcement could cause a shift of the column failure mode from flexure to shear under a relative low axial load level, and the corrosion level that could cause a failure mode change was be even lower when the column specimen was subjected to high axial load level. Li et al (2018) also reported that with the corrosion level of transverse reinforcement increasing, failure model could shift from bending to shear.…”

“…Li et al (2018) also reported that with the corrosion level of transverse reinforcement increasing, failure model could shift from bending to shear. In such cases, once peak shear capacity was attained, significant strength and stiffness degradation were observed, with more serious pinching effect (Vu and Li 2018a). As shear failure is generally more unpredictable and catastrophic, more attention should be paid to shear performance deterioration of corroded columns.…”

Service Life Prediction of Precast Concrete Structures Exposed to Chloride Environment

“…As chloride ions penetrate through concrete cover and accumulate at the steel surface, corrosion gradually initiates. Expansive corrosion products can further induce cracks and even reduce the shear bearing capacity of components and joint significantly [6][7][8][9][10] (shown in Figure 1). Some key points can be defined based on the mechanisms of corrosion and thus divide the process into different stages [11][12][13][14].…”