PSI - Issue 64

Hideki Oshita et al. / Procedia Structural Integrity 64 (2024) 48–55 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

52

5

kA/m 2

0

0.3 0.6

Electric current ： high

0

0.3 0.6

kA/m 2

kA/m 2

Electric current ： high

200

200

0.60 0.54 0.48 0.42 0.36 0.30 0.24 0.18 0.12 0.06 0

Upper region

Upper region

160

160

Electric current ： low

Electric current ： low

120

120

(cross section)

0.361

Middle region

(surface)

0.399

Middle region

80

80

0.282

0.309

40

40

Lower region

Lower region

(cross section)

(surface)

0

0

mm

mm

Induced current density

Induced current density

Induced current direction

Induced current direction

Fig. 5. (a) Distribution of induced current density (column); (b) Distribution of induced current density (beam)

3. Electromagnetic Induction Corrosion Prevention Effect in Microcell Corrosion of small-Scale Members In this chapter, we focus on verifying the effectiveness of our electromagnetic induction corrosion prevention method for microcell corrosion in small-scale column members. 3.1. Corrosion Prevention Conditions Based on Analytical Examination In currently practical corrosion prevention methods using electricity, for a corrosion protection area of 500 m², the power consumption is 12.5W. When converted to power consumption per unit area, it amounts to 0.025W. First, the experimental parameters have to be determined which satisfy the above value for induced current density using three-dimensional electromagnetic induction analysis. Next, we create test specimens with the same conditions as the analysis and quantitatively examine the corrosion prevention effect of our method on microcell corrosion. We also assess the impact of current values on this effect. (a) Analytical Overview The analysis model consists of a circular spiral coil with an inner surface of 150 mm and an outer surface of 152 mm as shown in Fig.6. The coil is wound with 2 mm diameter copper wire at 10 mm intervals along the axial direction of the reinforcing bar, forming 20 turns. Four standard round reinforcing bars (φ13, 200 mm in length) are concentrically placed at 90° intervals on the inner surface of the circular spiral coil, 10 mm away from the coil surface. The analysis parameters shown in table.1 are set to match those used in the induced current measurement experiments described in the above. Specifically, we set the current value and frequency to 1A and 10Hz, respectively. The analysis names follow the format of “S -A5- F500,” where S represents the indoor -scale member analysis model. (b) Induced Current Density Distribution for Corrosion Prevention Fig.7 shows the protective induced current density distribution along the circumferential and axial directions of the reinforcing bars. As shown in this figure, the induced current density in the circumferential direction satisfies the reference value (1A/m²) set. However, the axial induced current density is smaller than the reference value. Therefore, within the electromagnetic induction parameter range set for this experiment, it is inferred that we cannot effectively suppress corrosion current in the axial direction. 3.2. Electromagnetic Induction Corrosion Prevention Experiment (a) Experimental Overview