Recently, steel dampers are widely used as seismic reinforcement devices. Steel dampers have the advantage of being easy to manufacture and being able to absorb a lot of energy through stable hysteresis behavior. However, there is a possibility that the steel damper may be damaged due to fatigue caused by repeated seismic loads. In this study, the seismic performance of steel dampers and engineering plastic dampers with different physical characteristics were compared and analyzed. In addition, numerical analysis was performed on a hybrid damper that combines a steel damper and an engineering plastic damper. It is more effective to apply engineering plastic dampers to structures that experience significant displacement due to seismic loads. The behavior of hybrid dampers combining steel dampers and engineering plastic dampers is dominated by steel dampers. A hybrid damper in which an engineering plastic damper yields after a steel damper yields can effectively respond to various seismic loads and secure high ductility and excellent seismic performance.

Since the 2010 year, an occurring number of grand scale earthquakes which above magnitude 5.0 have increased in the world. Many types of research that deal with reducing the damage to the structure from a large-scale earthquake have proceeded. A system which could mitigate strong vertical earthquake's acceleration might apply to structure, since big earthquake cases that occurred lots of loss in Tokyo and Kobe of Japan. A plenty of bearings have installed to mitigate vibration but many parts of these lack efficient ability what we want. In addition, former vertical isolation bearings to apply for the structure have both price and size limits according to material characteristics. Therefore, this paper proposes a new type of device that is made by utilized engineering plastic and improves hitherto used vertical isolation bearing's fault.

Many polymers exhibits sufficient birefringence to be used as photoelastic specimen material. Common polymers as polymethylmethacrylate (PMMA) are often used as photoelastic specimen. In a photoelastic experiment, it is necessary to know the material fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. The material stress fringe constant is determined using the simple tension specimen. The stress fringe constant measured with this method is applied to obtain the stress distribution in a tensile plate with a circular hole. Photoelastic results using the measured material fringe constant are compared with FEM analysis. Two results are comparable, so it can be seen for the measured material fringe constant to be valid.