The strength of the challenge by building core areas on the outside of the side over the model be the lowest point for every 3 floors and are connected to the external tunnel.
Challenge the strength of the core area outside the building by one as conventional models. It has three floors and every room is connected to the tunnel outside.
Challenge the strength of the core building by outer space on one side a cliff simulation by point will be stay every 3 layers and connected to the tunnel outside.