Published February 25, 2019
Graduate Students: Huseyin Cilsalar
Principal Investigator: Michael C. Constantinou
Project Completion Date: 01-31-2019
This study concentrated on the development of a practical low-cost seismic isolation system for lightweight residential construction. The study concluded that single concave rolling isolators cast in high strength concrete with a steel-reinforced urethane rolling ball and a displacement restraint system represent a promising isolation system. A full size 1m square isolator suitable for application to typical reinforced concrete houses in Turkey was built and tested in a variety of configurations. The vertical stiffness, creep characteristics under gravity load and the lateral force-displacement characteristics have been studied.
There is an interest to develop practical, simple and reliable seismic isolation system for houses, which can be easily manufactured in most countries without the requirement for advanced technological capability. This concentrated on the development, construction, testing, modeling and validation of an isolator with these characteristics. Moreover, the work concentrated on the development and validation of design procedures for reinforced concrete houses equipped with this isolation system in areas of high seismic hazard in Turkey. The developed isolator is a single concave rolling isolator cast in fiber and steel-reinforced high strength concrete with a rolling ball made of urethane (Adiprene) in hardness of 95A or 62D and reinforced with a core of steel. The isolator also features a displacement restraint system to prevent collapse of the isolator at large displacements. For applications anywhere in Turkey, the isolator has an ultimate displacement capacity of 650mm after fully engaging the displacement restraint. The isolator was built and tested to determine its properties, including creep and lateral force-displacement characteristics. It was observed that the isolator exhibits significant rolling friction that is practically independent of the hardness of the rolling ball and the conditions of loading and motion. It also exhibits a post-elastic stiffness and an effective yield displacement that are much larger than those predicted by models assuming rigid rolling ball behavior. These properties are desirable and emanate from the viscoelastic behavior of the rolling ball.
This project was supported by the Turkish Government in terms of a scholarship (stipend and tuition) for the graduate student and by R.J. Watson, Inc.