| Abstract | The United Nations Industrial Development Organization (UNIDO) has, over the past five years, sponsored a research program for the development of low-cost natural rubber isolation systems for the seismic protection of public housing in developing countries. This program has led to demonstration buildings in China and Indonesia. The report describes the experimental studies on multi-layer high-damping natural rubber (HDNR) bearings with recessed end connections used in those demonstration buildings. An experimental program using samples of full-size bearings from the buildings in China was carried out to evaluate the properties of the isolators. The effects of the large displacement on the virgin bearings and the effects of the axial pressure on the isolator properties were investigated. In addition, the roll-out tests were also performed. The test results showed that the properties of the bearings agreed with the design values, and that the bearings have a displacement safety factor of 1.8 and a force safety factor of two. An extensive experimental program using samples of full-size bearings from the building in Indonesia was carried out to evaluate the dynamic properties of the isolators, and the factors that affect these properties. In addition , the roll-out tests, real time tests, and cyclic vertical tests were also performed. The test results showed that the properties of the bearings agreed with the design values, and that the bearings have a displacement safety factor of 1.3 and a force safety factor of 1.8. These experimental studies demonstrated that a well designed, fabricated, and installed HDNR isolation system can be an excellent choice in providing protection from strong earthquakes for public buildings,such as public housing, schools, and hospitals. Isolation reduces the floor accelerations and inter-story drifts to ensure earthquake prtection beyond life safety, and provides better performance in terms of building contents, non-structural... |
