Seismic Protection of Multistorey Buildings Through Base Isolation Techniques

This study deal with the performance of base isolation techniques in reducing the seismic response of multi-storey buildings. For symmetric and asymmetric building models by using finite element method in ETABS v21, the response of these models under seismic load using nonlinear time analysis methods was investigated. The study showed that the use of base isolation gives an increased the core fundamental time period, increasing from 0.75 seconds to 2.015 seconds for symmetric buildings, and from 0.74 seconds to 1.93 seconds for asymmetric buildings. this result helps avoid the impact of earth quake that maybe led to resonance and collapse the structures. The results  for the  displacement in isolated buildings was bigger  than that of fixed ones, so  flexibility and higher ability to reduce seismic impact. The displacement for symmetric buildings was about 50 mm in the isolated case, compared to 30 mm in the fixed case. As for drift, it increased to 0.015 in isolated buildings compared to 0.01 in fixed buildings, led to a good distribution for stresses in different storey. For Shear forces reduce  by  50% in isolated buildings, reaching about 1500 kN compared to 3000 kN in fixed buildings, and   overturning moment also decreased  to about 20,000 kNm in isolated buildings, compared to 40,000 kNm in fixed buildings, which improve  the stability of structures  and decrease  the possibility of damages. the above results proves that base isolation technics offer a good reduction in the seismic impact of structures, which increase the safety and stability of these structures under earthquake loads. The research recommends to using base isolation systems in seismic zones and provide a new design standards based on use of base isolation to have a good improve the ability of structures to resist seismic loads. In general, this study gives a strong confirmation of the fund of using base isolation systems to provide    a good resistance for the impact of seismic of multi-storey buildings, making a better in contribution for protecting lives and structures.