Seismic Rehabilitation of the Mackay School of Mines, Phase III, with Base Isolation

The original Mackay School of Mines Building was constructed in 1908. It is one of the original buildings of the University of Nevada, and is situated at the north end of the main quadrangle within the campus. Prominent in its location at University of Nevada and in appearance, the building is designated as a national historic monument. During the years of 1926 and 1956, significant structural alterations were made to the original building. Phase III work at the original Mackay School of Mines Building involves adding a library at the basement, with the balance of the building being remodeled for similar-type functions. Constructed mainly of unreinforced masonry, the seismic rehabilitation of the structure warrants careful attention. During the schematic phase of the work, both conventional strengthening and Base Isolation were explored as potential techniques with which to mitigate damage from earthquakes. Cost estimate of both schemes were also developed. From a preservationist point of view, there were definite advantages in the isolation design. Since the isolation system could filter out most of the damaging forces associated with earthquakes, none of the unreinforced masonry walls required strengthening. As a result, many of the original architectural features of the original building can be salvaged, maintaining the original quality of the building and its identity. For these reasons the Base Isolation option was selected as the seismic retrofit scheme. This paper illustrates the Base Isolation design for the Mackay School of Mines, a historical structure constructed of unreinforced masonry. The isolation system consists of high-damping rubber bearings in combination with sliding elements.