Azuhata, Midorikawa, and Ishihara 2008
This paper analytically investigated a self-centering system composed of rocking structural members that are allowed to uplift during an earthquake. This system can prevent steel building structures from experiencing residual deformation after severe earthquakes by using the effect of building’s self-weight to re-center. The energy dissipation mechanism is also investigated by means of analytical models. The force-deformation relationship of the rocking structural members is presented using numerical models. The 1995 Kobe earthquake and artificial ground motions were used as input ground motions.
System Concept
This system is composed of coupled braced units, rocking beams, yielding base plates, and visco-elastic friction dampers. There are two kinds of fuses in the system; yielding base plates at the bottom of each column of the first story and coupled braced units connected with vertical dampers. Yielding base plates work like footing dampers and control uplift response. Connecting dampers improve energy-dissipating performance. In addition, one side rocking beams are used. When the rotational direction at the beam ends is reversed due to earthquake lateral force effect, these edges can uplift freely.
Analytical Study, Results and Discussion
The linear acceleration method is used for a seismic response analyses. The force deformation relationship of columns, bending-deformation relationship of edge parts of columns, axial force-deformation relationship of braces, shear force-deformation relationship of the vertical dampers were examined. The relationships between the roof displacement and the base shear of the original braced frame model with FIX model and the proposed SCR model was obtained by static pushover analyses. The base shear of the SCR model was seen to be smaller than those of the FIX model. However the corresponding roof displacement of the SCR model is almost equal to or smaller than that of the FIX model. As a result, the self-centering system with rocking structural members was proposed to reduce seismic damage of steel buildings.
Reference
Azuhata, T., Midorikawa, M., and Ishihara, T. (2008). “Earthquake Damage Reduction of Buildings by Self-Centering Systems Using Rocking Mechanism,” Proceedings of the 14th World Conference on Earthquake Engineering, Beijing, China, October 12-17.