One of the very important aspects to consider when a skyscraper is done is that the higher the greater height is the effect of the wind on its structure. To counteract this effect at lower buildings it is common to stiffen the structure with a bracing X to prevent deformation or displacement thereof in some cases by the outside or with walls of reinforcement around the vertical communication cores. This process in a steel structure high-rise would be extremely expensive, in the case of the Sears Tower.