Elastic inter-story drift seismic demand estimate of super high-rise buildings using coupled flexural-shear model with mass and stiffness non-uniformities

With a major concern regarding the preliminary seismic design of super high-rise buildings, a modified flexural-shear model (FSM-MS) is developed and well-targeted to account for the dual non-uniform distributions of story mass and stiffness, and to provide an efficient estimate of their maximum inter-story drift (ISD) demands. The analytical solution to the differential equation of the free vibration of a system is achieved by the rationally assumed correlations of the distribution functions among flexural stiffness, shear stiffness and story mass. With the statistical relations for the first two periods from 124 super high-rise frame core-tube buildings, a code-compliant estimate of the elastic maximum ISD and a corresponding strategy for the ISD-targeted stiffness demand estimate are developed. The holistic design feasibility, efficiency and accuracy of FSM-MS is fully demonstrated by three case super high-rise buildings with different heights and non-uniformities. FSM-MS combined with the code-specified design response spectrum and the modal decomposition method is more specialised in offering an efficient and reasonably conservative estimate of the maximum ISD demand of super high-rise buildings.