INVESTIGATION OF TRANSITION STORY EFFECT ON BEHAVIOR OF VERTICALLY HYBRID BUILDINGS

Hybrid buildings, which consist of two different structural systems in height, don’t show good seismic response. Use of reinforced concrete (RC) frames for lower stories and steel frames for upper stories is an example of hybrid buildings and under the earthquake loads, steel frames may slip on lower concrete parts. In this paper, linear and nonlinear behavior of 5, 10 and 15 story buildings that have RC frames with shear walls in lower stories and steel frames with bracings in upper stories is investigated. Analytical results show that using transition story between two different parts of hybrid structures improves the seismic behavior of these buildings. Transition story, which is located in the transition level, is a composite (steel-concrete) story with composite columns, shear walls and steel bracings. Number of these transition stories is dependent on the height of the building and applied loads. The best position of this story is at one-third of the height of hybrid building from top. Moreover, with using transition story in hybrid structures, axial and shear forces at transition level decrease and ductility increases.