>> It is well known that reinforcement details in the plastic hinge region of bridge piers give the most important effects on the seismic performance of bridges, from investigations of bridge failures in many earthquake events and in laboratory tests. Longitudinal reinforcement details give larger effects than lateral reinforcement details do. The lap-spliced longitudinal steel shows slip during earthquake events, which results in low ductility and inadequate seismic performance. However,

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... the issue of the earthquake design code, a considerable number of bridge piers were constructed with lap-spliced longitudinal steel in the plastic hinge region. Therefore, a large amount of research has been conducted on the seismic performance and retrofit of circular and rectangular shaped bridge columns with lap-spliced longitudinal steel. However, research on wall type piers is very limited. This paper investigates the seismic performance of a pier wall by a quasi-static test in the weak axis direction and proposes a retrofit method. From the test with variables being the longitudinal steel detail and the transverse steel amount, it is shown that the currently used definition of yield displacement is not adequate. Therefore a new definition of yield displacement for the ductility investigation for a pier wall is proposed. In addition, a retrofit method by steel plates and bolts is proposed to improve ductility, and test results show that slip of the longitudinal steel is prevented by up to a considerably large displacement. <표 1> 조사된 벽식 교각의 변수 범위 조사항목 변수 범위 교축방향 단면두께 [m] 0.6~2.2 교각 높이 [m] 2.4~10 축방향철근 지름 [db] D 1 3 ~D29 축방향철근비 [%] 0.2~1.67 띠철근 지름 [db] D 1 3 ~D22 띠철근 간격 [mm] 150~400 콘크리트설계강도 [MPa] 21~27 철근의 항복강도 [MPa] 300