S. A. Zahraei - Research Assistant, Building and Housing Research Center of Iran
R. Edalatmanesh - Research Assistant, Building & Housing Research Center of Iran
S. M. Zahrai - Assistant Professor, University of Tehran
K. Khalili - Researcher, Building and Housing Research Center of Iran

Due to easy construction together with low cost of jack arch slabs, they have been widely used in many countries like Iran. Nowadays, many low-rise buildings are still constructed by this flooring system .More than 50 percent of existing low to medium rise buildings have already used non homogeneous jackarch slabs that are supposed to be engineered with appropriate methods. For this purpose, two different specimens of one story building with this kind of slab were constructed and subjected to gravity and lateral loadings simultaneously. In the first test, an ordinary traditional jack-arch slab was built and tested. Subsequently, in second specimen a retrofitted jack-arch slab according to Iranian code of practice for seismic resistant design (standard NO.2800) was tested. Comparing these experimental results shows that the retrofitting approach proposed by standard NO.2800 can improve the seismic structural behavior; for example, diaphragm performance of jack-arch as well as the stiffness of ceiling will be enhanced. Moreover, study of ductility factor shows a striking improvement in capability of energy dissipation in the retrofitted steel frame. Finally, a cost review will disclose that retrofitting an existence floor slab is more economical than replacing it by a new one, but for constructing new building, a joist and block slab is a better choicecompared to a retrofitted jack-arch slab.

Jack-arch slab, retrofitting, diaphragm, ductility factor, cyclic testing