A new stiffness design method is presented for finding the set of storey stiffnesses of the elastic shear building, supported by prescribed frequency-dependent complex springs, which exhibits a specified distribution of mean peak interstorey drifts under design earthquakes, A frequency-independent substitute model is introduced to estimate seismic responses of the original frequency-dependent model. A closed form solution to a hybrid inverse eigenmode problem is derived and the qualification conditions on the specified fundamental frequency and eigenvector are disclosed. The formula is then shown to be useful for developing the efficient seismic stiffness design method. Response analysis on the original frequency-dependent model in the frequency domain is required only for demonstrating the validity and accuracy of this design method.