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The authors have developed a new vibration-controlled system effective for high-rise RC buildings against long period, long duration ground motions which are highly concerned recently. The system has a couple of shear-walls with pins at the bottoms to utilize oil dampers effectively by amplifying its deformation. To demonstrate the effectiveness of the system, it is important to carefully design the damper connections between different materials (steel and concrete). Since the proposed system is complex, experiments are required to evaluate its properties. The objective of this study is to clarify the mechanical property of the connection between a couple of shear-walls and dampers and to construct a simplified analysis model for design. First, cyclic loading experiments using three types of T-shape specimens (normal, cracked and reinforced) were conducted for evaluating their stiffness and durability. As the magnitude of loaded force or the number of loadings becomes larger, the stiffness of the connection between a couple of shear-walls and dampers becomes lower due to extension of cracks at the internal corner. However, it keeps high stiffness compared with that of dampers and the residual crack width is small. Under the maximum damper force, the strain of reinforcement bar is lower than the yield strain. Secondly, finite element analysis was conducted to simulate the actual behavior. The analysis model is 2-dimensional and elastic plane elements are used to simplify the analysis. In order to take into account the non-linearity caused by cracks, the model is divided into two parts by the presumed crack line and they are connected by 1-dimensional non-liner springs representing the properties of concrete and reinforcement bars. Stiffness decrease is mainly caused by the crack at the internal corner, and it converges due to balance of loaded force and reinforcement bar stress. Since diagonal bars are highly related to the connection stiffness, the increase of diagonal bars improves it effectively. Finally, a simplified analysis model of damper connection was proposed to enhance the usability in the usual structural design. To consider the effect of the internal corner crack in more detail, an additional spring is introduced in the form of series type through rigid elements and beam elements. It is easy to adopt because all elements are only composed by beam elements. It is concluded that the connection between a couple of shear-walls and dampers has sufficient stiffness and durability against long period, long duration ground motions. |
