Specimen C3

When the horizontal force reached 76 kN, the first horizontal crack appeared 150 mm from  the root of the column,  with a width    of

0。02 mm。 When the steel bars reached the yield strain, the number of cracks in Specimen C3 was much less than that in Specimen C1。 In the first loop of the 3Δy loading, the horizontal load reached its peak value, and the textile fractured at right angles to the column root and the surface of the reinforcement layer, although the vertical cracks had a longer extension。 In the 7Δy loading, the horizontal bearing capacity fell below 85% of the peak load, the reinforcement layer heaved in the root of the column, and the textile fractured severely。 The longitudinal reinforcements were chiseled out after the test, and the measured corrosion ratio of the steel was   3。76%。

Specimen C4

Severe corrosion cracks appeared in the concrete surface of Specimen C4, with a width of 0。02 mm。 The overall corrosion of the specimen was serious。 When the horizontal force reached 76 kN, horizontal cracks appeared 280 and 310 mm from the root of the column。 The number of cracks increased slowly during the loading process, and the existing corrosion cracks developed con- tinuously。 When the horizontal force was 84 kN, the steel bar yielded。 The yield load of Specimen C4 is slightly higher than that of Specimen C1 due to the uneven corrosion of the steel bars and the enhanced bond strength of the reinforcing steel in the small corrosion ratio region。 In the first loop of the 3Δy loading, the hori- zontal load reached its peak value。 The peak bearing capacity of Specimen C4 was lower than that of Specimen C1, and the concrete was severely crushed。 In the 6Δy loading, the horizontal bearing capacity fell below 85% of the peak load。 The longitudinal rein- forcements were chiseled out after the test, and the measured cor- rosion ratio of the steel was  8。27%。

Specimen C5

When the horizontal force reached 84 kN, horizontal cracks ap- peared 200 and 300 mm from the root of the  column,  crossing the section, and the width of  the  cracks  was  0。04  mm。 When the horizontal force was 92 kN, the steel bar yielded, the vertical cracks increased at right angles to the column root, and mortar fell off from the surface of the reinforcing layer。 In the first loop of the

3△y loading, the horizontal load reached its peak value。 Compared with Specimen C4, fewer new cracks appeared in the concrete

surface of Specimen C5。 The existing vertical cracks extended to a length of approximately 300 mm, and the textile clearly frac- tured。 In the 7△y loading, the horizontal bearing capacity declined rapidly, the textile fractured almost entirely at a right angle to the column root, and the internal concrete was crushed。 The longitu- dinal reinforcements were chiseled out after the test, and the mea- sured corrosion ratio of the steel was   7。35%。

Specimen C6

Specimen C6 experiences largely similar phenomena to Specimen C3 in the early stage of loading。 When the horizontal force reached 76 kN, horizontal cracks appeared 100 and 200 mm from the root of the column, with a width of 0。04 mm, and they clearly extended to both sides。 When the horizontal force was 84 kN, the steel bar yielded, there were fewer cracks, and mortar fell off from the sur- face of the reinforcing layer。 In the first loop of the 3Δy loading, the horizontal load reached its peak value, the textile fracture increased on the surface and at a right angle to the column root, and a ladder- shaped textile fracture formed on the surface of the reinforcement layer, which was also the case in Specimen C3。 In the 6Δy loading, the horizontal bearing capacity fell below 85% of the peak load, the reinforcing layer heaved in the root of the column, and the internal concrete was crushed。 The overall failure mode of Specimen C6 was better than that of Specimen C4。 The longitudinal reinforce- ments were chiseled out after the test, and the measured corrosion ratio of the steel was  8。69%。