Yuto TAMURA

Effect of Corrosion of Stud on Mechanical Properties in Steel-Concrete Composite Structures

Takumi SHIMOMURA

In steel-concrete composite structures, there is concern that mechanical performance may be impaired if corrosion occurs at joints. In this study, experiments were conducted to understand the effects of corrosion on headed studs, which are commonly used to prevent misalignment.
First, experiments were conducted to investigate the introduction and propagation of corrosion cracks when corrosion occurs on headed studs. Two specimens were made to simulate steel-concrete composite joints, and corrosion was applied to the studs by the electrolytic corrosion method. One specimen had one stud and the other had two studs. The studs were placed at a minimum spacing of 100 mm according to the Standard Specification for Composite Structures. After corrosion cracks were visually observed on the concrete surface, the electrolytic corrosion was terminated and the corrosion cracks were investigated. In the specimen with one stud, cracks were observed in four directions from the stud to each concrete surface, whereas in the specimen with two studs, one crack was observed to crack the concrete in the axial direction of the stud. This indicates that corrosion cracks were introduced into the concrete when corrosion occurred at the studs. It was also observed that corrosion cracks were connected between studs when the stud spacing was small.
Next, the effect of the connection of corrosion cracks between studs on the mechanical properties was elucidated. Three specimens with stud spacing of 100 mm were fabricated based on the Japan Steel Structure Institute's (JSIS) draft push-pull test method for studs with heads. The mechanical performance of each specimen was investigated by electrolytic corrosion tests at three levels of deterioration due to corrosion: latent, advanced, and accelerated stages, followed by push-pull tests. It was confirmed that the corrosion cracks were connected between studs with a mass loss rate of about 2%. The mechanical performance was found to be less affected if the corrosion cracks were connected on the concrete surface with a corrosion loss of about 2%. However, the effect of more advanced corrosion and wider cracks on mechanical performance has not been clarified and should be investigated in the future.