Structural engineers examined a variety of solutions before coming to the final structural configuration of Taipei 101. Initially, a framed tube was examined. Such an arrangement would block the wide glass expanses, feature strongly desired by the owners. Furthermore, it would have created indirect transfer-loadings in every of the transition floors (in the eight setbacks). Furthermore, a bundled tube was considered. Although such a solution would have created wider column spacing as compared to a tubular frame, the internal frame lines would create a "picket fence" effect that would subdivide the floors and restrain the use of the floors. A "tube in tube" would mean a central core and a perimetric core, which would again require very close spaced exterior columns.