The picture above is a circa 1896 ice palace in Leadville, Colorado. The one below is a 1909 ice fort in Saranac Lake, New York.
People still build these things, and it got me thinking about how to design one. In short, ice (if we assume temperatures at least ten degrees below freezing) is a stable and solid material with pretty good compressive strength (700 psi and up), tensile strength about one eighth of its compressive strength, and subject to brittle failure. In other words, it equates pretty well to nineteenth-century brick, and we don’t spend a lot of time wondering if that works as a building material.
While one could, in theory, reinforce an ice building by freezing the ice around rebar or even laying rebar against a wall and then spraying water to bind it in, this has been done rarely, if ever. Most ice buildings are simply unreinforced masonry, and therefore use the constructive language of the material: walls, piers, corbels, arches, and vaults.
People built early skyscrapers – at the time of the Leadville palace – using unreinforced brick. I will probably never get the opportunity to build an ice skyscraper, but I can dream.