Direct Displacement-Based Seismic Design Method of High-Rise Buildings Considering Higher Mode Effects

Direct displacement-based Seismic design of high-rise buildings considering higher mode effects is realized. The structural natural periods and corresponding modes are obtained by free vibration analysis. Based on the periods, the equivalent displacement of single-degree-of-freedom system for each mode is obtained by displacement response spectra, and the structural lateral elastic displacement of each mode could be determined by “Equivalence Principle”. So the structural lateral elastic displacement can be deduced by SRSS rule. Then, based on allowable storey drift ratio, the structural target lateral displacement of each mode could be determined, and the storey shear is obtained by SRSS rule. The design example shown in Table 3 demonstrates that the base shear considering higher mode effect in serviceability performance level is 2212kN, that is larger than 1975kN which only considering the first mode, so the design results will be more safety. The elasto-plastic time history analysis proves that this method is accurate enough to practical application in building design.