Stiffness Design of 3‐D Shear Buildings for Specified Seismic Drifts

Abstract

The closed‐form solution is derived to the problem of stiffness design of coaxially coeccentric asymmetric shear buildings (CCS buildings) for specified fundamental natural frequency and eigenvector. The complete quadratic combination (CQC) estimates of the mean maximum interstory drifts in a so‐designed CCS building subjected to an ensemble of design‐spectrum‐compatible moderate earthquakes are regarded as functions of the lowest eigenvalue and translational eigenvector, parameters for adjustment of those CQC estimates. An almost direct and efficient method of stiffness design is developed for a CCS building such that all the CQC estimates of the mean maximum drifts of the corner columns based upon a prescribed design spectrum will be equal to the prescribed distribution of design drifts. The validity of the design procedure is demonstrated with the results of time history analysis on so‐designed CCS buildings. A design amplifier factor for specified distribution of lateral torsional drifts is defined and is shown to be useful for describing directly the effect of eccentricity on the seismic response‐drift constrained designs of CCS buildings.