Seismic Ductility Reduction of Flexural-type Structures with Vertical Irregularities

Abstract

Seismic ductility reduction factors for flexural-type structures with vertical irregularities subjected to pulse-like and nonpulse-like ground motions are investigated in this paper. By establishing various multi-node flexural cantilever-column models, the ductility reduction factor of vertically irregular structures is studied by modifying the ductility reduction factor of irregular structures. The effects of various factors such as ductility level, irregular ratio and pulse-like earthquake excitation on modification coefficient are also explored. The analysis results reveal that: 1) the modification coefficient decreases with smaller irregularity ratio; 2) ductility reduction factors for vertically irregular structures are significantly smaller than those of regular structures; 3) ductility level exerts a certain influence on ductility reduction factor without an obvious trend; and 4) the modification coefficient under pulse-like excitation is smaller than those from non-pulse-like motions and the influence of pulse-like earthquake is coupled with irregularity ratio. This paper concludes with the statistical outcomes based on average of results and recommends modified factors for practice uses.

Influence of the P-delta Effect and Stiffness Irregularity on the Structural Behavior of Reinforced Concrete Buildings

“…It can even cause dynamic instability when the structure is subjected to severe seismic movements [8]. Regarding the irregularity of stiffness; Zhao, Hu y Long [9] mention that the vertical irregularity or height of a structure is introduced by abrupt changes or discontinuities in the configuration (such as dimension, soil mass, rigidity, resistance or their combination) along its vertical direction. As a consequence, large stresses or concentrations of plastic deformation can occur in the local weakness and spread to global damage or even collapse.…”