.The pre-tensioned high-strength concrete special-shaped hollow piles in this atlas are suitable for low-capacity vertical foundation piles of general industrial and civil buildings and structures in areas with seismic fortification intensity of 7 degrees and below, municipalities, bridges, railways, highways, etc. The design of low-capacity vertical piles for airports, ports, water conservancy, electric power and other projects can be used as a reference, but it should comply with the relevant national standards.