Seismic evaluation and rehabilitation of reinforced concrete bridge wall piers

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75 3.6.2.1.4 Damage Assessment The damage assessment was performed according to the description made in Section 2.3.2.1.6, and damage index was plotted against different damage level, as shown in Figure 3.26. The obtained plot shows moderate damage degree after the 1.0 % drift ratio. The repaired specimen was severely damaged after 2 % of the drift ratio. The specimen reached the collapse point at the 5 % drift ratio and finally failed at the 6% drift ratio. 3.6.2.2 Performance of the Repair System 3.6.2.2.1 Headed Rebar Performance The headed steel bars were used to transfer the tensile force between the wall pier and the footing. On both sides of the repaired specimen, the strain gauges were placed on headed steel bars at 2 in. height from the top of the footing. According to the strain gauge data, the headed steel bar on the east face was strained more than those at the west face. At a 3.7 % drift ratio, the middle headed steel bar on the east side reached a maximum 55 % of the yield strain whereas the middle headed rebar in the west side only could reach a maximum 36 % of the yield strain. 3.6.2.2.2 CFRP Shell Performance The CFRP sheet composite wrap around the repair region provides the confinement and shear strength to the repair concrete and the wall piers. The strain gauges were placed at 3 in., 8 in., 15 in., and 20 in. from the top of the CFRP shell to measure the hoop strain. Figure 3.27 shows the hoop strain recorded in the east side of the wall pier is 0.07 %, which is double in comparison to the west side whose reading shows 0.03 %, showing more