Ductile Seismic Design of Steel-Concrete Composite Structures : Capacity Design Taking into Account the Effect of the Variability of Mechanical Properties of Materials

In order to allow the formation of the greatest number of plastic hinges and to dissipate as much as possible seismic energy of moment-resisting frames, dissipative zones should be mainly located in plastic hinges in the beams or in the beam-column joints, but not in the columns except at the base of the frame. It is clear that this design method strongly depends on actual mechanical properties of materials. The possibility that the actual yield strength of steel is higher than the nominal yield strength in dissipative zones should be taken into account by a material overstrength factor for the design of non-dissipative zones. In spite of the fact that this point is essential in seismic design, the value to be given to this overstrength factor varies in the provisions of different standards. Moreover, these standards don't provide adequate limitations on mechanical properties for steel products even if it should be directly related to the overstrength factor chosen. For these reasons, this work aimed to define suitable harmonised rules and recommendations for production standards and structural regulations for steel-concrete composite structures located at earthquake-prone areas.