A general approach using a multi-high-frequency-force-balance system (MHFFB) is presented to determine the wind-induced response of a complete building complex from wind tunnel tests. A building complex consists of several building towers being structurally connected either through skybridges or by a common podium. By dividing the whole structure into several substructures, the overall generalized wind loads can be determined from simultaneous measurements on each individual substructure. A treatment for nonlinear mode shapes is also presented. A qualitative analysis for a twin tower structure reveals a general phenomenon that the structural connections between towers tend to increase the wind-induced response for the tower which experiences relatively lower wind loads but tend to decrease the wind-induced response for the tower which experiences relatively higher wind loads. The presented method provides a tool to quantitatively estimate this effect. The application of the presented method can also be extended to some torsionally sensitive structures, for which the traditional force balance technique can hardly provide satisfactory estimates.