Not much of the exterior shells of these super tall buildings are concrete. Those are the areas that are experiencing large deflections, i.e. are bending in res

Not much of the exterior shells of these super tall buildings are concrete. Those are the areas that are experiencing large deflections, i.e. are bending in response to the wind. The floor slabs are concrete, but they are essentially rigid and do not see much bending that would cause cracking. The notion of a shear wall and/or shear core allows for the strength of reinforced concrete in shear to be taken advantage of, while not exposing the concrete to deflections that would induce cracking. Not a "vertical transportation" guy, but elevators are often placed in the center of buildings, surrounded by shear walls precisely for the same reason that shear walls are. Less bending, less chance for displacements. https://en.wikipedia.org/wiki/Shear_wall https://en.wikipedia.org/wiki/Shear_wall