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The Steel reinforced concrete (SRC) structures are typical composite structural systems consisting of steel and reinforced concrete (RC), which have an excellent earthquake resistance and deformability. However, the design process and construction work are more complicated than those for steel structures and RC structures. In order to solve these problems, Concrete Encased Steel (CES) structural system consisting of fiber reinforced concrete (FRC) and encased steels only, have been proposed by the authors as a new composite structural system, and continuous and comprehensive studies have being conducted to make it practical. On the other hand, shear walls for the major seismic member are effective to increase the strength and stiffness of the CES structural system. However, it will be difficult to arrange wall reinforcing bars in the CES shear walls. Recently, there have been some researches on methods of jointing a frame and wall panel in SRC shear walls. It is likewise an important problem to improve the workability of a CES frame and FRC wall panel joint in the CES structures. Cyclic loading tests were carried out on CES shear walls with different anchorage methods for the CES frame and FRC wall panel, and the basic structural performances, such as strength and failure modes, of the CES shear walls were investigated. As a result, it was confirmed that the effect of anchorage condition of wall longitudinal reinforcement on shear strength and flexural strength of CES shear walls is not significant. In addition, the deformability of CES shear walls improves by omitting anchorage of wall longitudinal reinforcement. However, it is difficult to fully understand the behavior of CES shear walls which consist of many members, such as boundary columns, wall panel, boundary beams, steels and wall reinforcing bars. This study is aimed to confirm the basic structural performance, such as internal stress conditions, of CES shear walls. A two-dimensional non-linear FEM analysis for CES shear walls was conducted to verify the validity of analytical modeling assumed and constitutive modeling for materials used. Internal stress conditions in CES shear walls were also investigated through the FEM analysis. Analytical results for the shear force versus drift angle relationships and deformation components of the shear walls showed good agreements with the experimental results, namely it was found that the behavior of the CES shear walls can be approximately simulated by the analytical model. It was also indicated through the analysis that the difference of anchoring method of longitudinal wall reinforcing bars to boundary beams affects little on the internal stress conditions and overall behavior of the shear walls. |
