Investigating Effects of Initial Strain on the Seismic Behavior of the Tensegrity Grid Structures

Tensegrity structures are a family of space structures that mainly consist of two distinct member types: first the members that merely bear compression or bar members, second members that bear only tension or cables. In these structures, cables are used in the place of the tension members, so they are even lighter in weight. These structures need to be pre-stressed to be stable. After being introduced in by these structures are extensively studied statically. However, there are a few researches in the field of dynamic behavior of the tensegrity structures and even less is in the field of seismic behavior. Recent earthquakes around the world revealed that despite preliminary expectations, the space structures are not entirely aseismic structures. In this paper a tensegrity grid structure with various amounts of initial strains is considered and its behavior under threeearthquakes of Northridge 1994, Imperial Valley 1979 and Tabas 1978 are examined. It is shown that the tensegrity grids are sensitive to initial strains and although the initial strain make a tensegrity grid stiffer, but makes it brittle.