Cyclic Behavior of Reinforced Concrete Beams with Corroded Transverse Steel Reinforcement

Abstract

This study examined the seismic performance of reinforced concrete beams with corrosion only induced in the transverse steel reinforcement by using cyclic loading. The beams were designed with closely spaced steel hoops as transverse reinforcement conforming to the seismic design provisions of the ACI 318 code. Seven beams were constructed. One beam was used as a control without corrosion. The other six beams were subjected to six levels of corrosion in the potential plastic hinge region by using an electrochemical method. Corrosion test results indicated that pitting corrosion increased with an increasing corrosion level. The hoops fractured at a corrosion weight loss of 35%. Cyclic test results indicated that the beams could sustain a corrosion weight loss of 6% in the hoops and still maintain ductile flexural behavior. The corrosion of hoops adversely affected the deformation capacity of the beams significantly, yet did not significantly influence the load-carrying capacity of the beams. The residual shear strength provided by concrete and steel was still sufficient to develop flexural yielding, even for beams with hoops corroded to fracture. Methods were developed to estimate the residual shear strength and ductility of reinforced concrete beams with corroded hoops. The amount of corrosion substances filled in the cracks’ volume was approximately 25% of the reduced volume of steel due to corrosion. Although shear strength estimation based on the average corrosion weight loss was not conservative, the shear strength estimation based on the minimum residual cross-sectional area was too conservative at a high corrosion level due to severe pitting corrosion. Shear strength estimation based on average weight loss and minimum residual cross-sectional area produced results that describe the experimental behavior more reasonably.