this question is based on the st. louis arch video. how long is the st. louis arch designed to last
Gateway Arch The structural load is supported by a stressed-skin design.[69] Each leg is embedded in 25,980 short tons (23,570 t) of concrete 44 feet (13 m) thick[58] and 60 feet (18 m) deep.[70] Twenty feet (6.1 m) of the foundation is in bedrock.[70] The arch is resistant to earthquakes[71] and is designed to sway up to 18 inches (46 cm) in either direction,[72] while withstanding winds up to 150 miles per hour (240 km/h).[73] The structure weighs 42,878 short tons (38,898 t), of which concrete composes 25,980 short tons (23,570 t); structural steel interior, 2,157 short tons (1,957 t); and the stainless steel panels that cover the exterior of the arch, 886 short tons (804 t).[61] This amount of stainless steel is the most used in any one project in history.[66][73] The base of each leg at ground level had to have an engineering tolerance of 1⁄64 inch (0.40 mm) or the two legs would not meet at the top.[7]