Abstract.In the past, the authors studied the fire resistance of protected steel columns in firei). '

Accelerated corrosion tests of reinforced concrete (RC) specimens were conducted to estimate the corrosion expansion rate of reinforcing bars. Subsequently, finite element analysis was performed with the estimated expansion rate for RC beams to investigate concrete cracking induced by corrosion. The influence of the different confinement levels on crack behavior was investigated using mainly the amount of transverse reinforcement. An expansion rate of 2 was found to be appropriate when using Lundgren’s expansion model. Confinement levels affected the cracking behavior of steel bars. Cracks did not significantly affect structural capacity although they exceeded the allowable crack width. Nevertheless, repair and reinforcement measures are necessary because degrading durability factors such as carbonation or salt diffusion can reach the reinforcing bars through connected cracks.

No abstract

This study performed accelerated corrosion tests on reinforced concrete (RC) specimens reinforced with transverse steel bars to evaluate the concrete cracking and rebar strain behaviors caused by rebar corrosion. Seven RC specimens were created with variable compressive strengths, rebar diameters, and concrete cover thicknesses. To mimic in-situ conditions, the accelerated corrosion tests applied a current to the longitudinal bar and transverse bar for different periods of time to create an unbalanced chloride ion distribution. These tests evaluated the amount of rebar corrosion, corrosion cracking properties, and transverse bar strain behavior. The corrosion rate of the transverse bar was faster than that of the longitudinal bar, and cracking first occurred in the concreate around the transverse bar in the specimens with low concrete compressive strength and thin concrete cover. Corrosion cracking and rebar strain were greatly affected by the behavior of the corrosion products that resulted from the pore volume and cracking properties of the cement paste.

Recent approaches to the design of reinforced concrete members have paid attention not only to shear failure as a primary cause of collapse, but also to shear damage from the viewpoint of serviceability and durability. Tests were performed on RC columns having axial load ratios of 0 to 0.3, and shear reinforcement ratios of 0.29% and 0.63% in order to study the influence of axial load and shear reinforcement upon the shear-transfer mechanism while shear damage was in progress. Resistance against shear damage increases with an increase in shear reinforcement, but the shear-transfer ability, due to the concrete contribution, decreases with an increase in shear reinforcement and axial load. A method for evaluating shear damage has been proposed based on the shear-transfer mechanism of concrete and reinforcement. FEM analyses have been also carried out to verify the transition of the shear-transfer mechanism estimated by the proposed method.