Base isolation by geosynthetic for brick masonry buildings

Abstract

The use of geosynthetic in civil engineering applications has experienced tremendous growth. The concept of seismic isolation is applied here for vibration control to masonry buildings by separating the superstructure from the foundation at plinth level by a sliding earthquake energy reducing friction layer in the form of green marble/geotextile sliding couple. The dynamic properties of the friction interface have been investigated. The effect of the ground motion on the behavior of a friction isolation system is investigated analytically by using a synthetic accelerogram that is compatible with the design spectrum of Indian Standard corresponding to the level of maximum considered earthquake in the most vulnerable seismic zone (PGA = 0.36 g) of India as well as a recorded accelerogram of the El Centro earthquake. It is observed that the frictional base isolation provided by the geotextile limits the earthquake energy transmission to the superstructure during a strong earthquake. Fifty per cent reduction in absolute response acceleration at roof level for the isolated structure is obtained compared with a fixed base structure at the cost of peak base sliding displacement, which is well within a plinth projection of 75 mm (3 in) and appears to be a more economical and more practical choice than other alternatives for frictional base isolation of a single story brick masonry structure.