Recently, high-rise residential buildings in Korea have adopted slender shear walls with irregular section shapes, such as T-shape, H-shape, and C-shape. In the seismic design of the slender shear walls, the transverse reinforcement for lateral confinement should be provided in the boundary elements to increase deformation capacity and subsequent ductility. However, in practice, the irregularity of the shear walls is not adequately considered, and the lateral confinement region is calculated for the rectangular wall segments. This study investigated the proper design method for lateral confinement regions using finite element analysis. The lateral confinement region was considered in analysis for two cases: 1) as a typical rectangular wall segment and 2) as an irregular wall. When the irregularity of the walls was considered, the compression zone depth was increased because the vertical reinforcement in the flange was addressed. The effect of lateral confinement design methods on the structural performance of the walls was directly compared under various design parameters, including the length of the flange, concrete compressive strength, vertical rebar layout, axial load ratio, and loading direction. According to the results of the parametric analysis, the peak strength and deformation capacity could be significantly increased when the lateral confinement region was calculated based on irregularly shaped walls, regardless of the design parameters. In addition, the effective compression zone was located within the lateral confinement region. Thus, it is recommended that the lateral confinement region of T-shaped walls is calculated by addressing the irregularity of the walls.

This paper investigates experimentally the confinement effect on concrete. For this purpose, outside lateral reinforcement members made of stainless steel and GFRP were employed. Then, uniaxial compressive tests on concrete cylinders incorporating the members were conducted. A total of 30 cylinder specimens, specifically, 6 unconfined specimens, 12 specimens confined by stainless steel and 12 specimens confined by GFRP, were fabricated. The failure patterns of both unconfined and confined specimens were assessed and discussed based on experimental results. The results proved that the maximum stress and corresponding strains of the cylinders confined using the proposed hoops are increased in comparison with those of the unconfined. This supports that the current work can be used for retrofitting concrete members and structures and thus may lead to increased stability of such structures.