Abstract:

Based on a reasonable assumption of modeled structures,simplified analytical relationships between global ductility demands and local-storey ductility demands,as well as between local-storey ductility demands and vertical element ductility demands,are derived by theoretical analysis for multi-rise structures. Both the most unfavorable analytical relationship and the numerical results indicate that ( 1) the local ductility demand of the weak storey is larger than the global one and increases owing to any additional storey; ( 2) the post-yield stiffness of storey greatly influences the relationship between the local and the global ductility demands; ( 3) the relationship between the soft-weak column element and the local storey ductility demands correlates with the lateral stiffness ratio and the yield strength ratio of the strong column to the weak column; and ( 4) the ductility demand of the soft-weak column ( the lower limit) decreases with the increase in the stiffness ratio but increases ( the upper limit) with the yield strength ratio.

Key words: building structure, ductility demand, lateral stiffness, theoretical analysis