Design Aspects in Seismic Isolation: Application to Retrofit Churches

The severe damage to masonry buildings after earthquakes has pointed out the need of studying new seismic protection techniques in order to guarantee appropriate safety levels against earthquakes. In historical buildings, such as basilica churches, a seismic rehabilitation should have also a minimum impact on the construction, preserving the original structure as far as possible. The Base Isolation System (BIS) balances the opposite requirements of structural safety and architectural preservation. In this article, the design of BIS for retrofitting masonry churches is discussed and applied to four case studies. Dynamic behavior of the isolated structures is evaluated and compared with the “as is” structures. Some major design issues are examined, namely: the use of mixed isolation system for lightweight buildings; the values of design vertical stress on isolators and the effect of selecting different rubber compounds and isolator geometry; and the effect of rigid slab at the isolation plan on the stress distribution among isolators.