This specification covers corrugated steel pipe and pipe-arches, ribbed and composite ribbed steel pipe, ribbed pipe with metallic-coated inserts, closed rib steel pipe, composite corrugated steel pipe, and steel structural plate pipe, pipe-arches, and underpasses for use as storm sewers and sanitary sewers, and other buried applications. The design load or pressure on a pipe is comprised of earth load, live load, and impact load. These loads are applied as fluid pressure acting on the pipe periphery. Strength requirements for wall strength, buckling strength, and seam strength may be determined by either the allowable stress design method or by the load and resistance design method. The thrust in the pipe wall shall be checked by three criteria. Each considers the joint function of the steel pipe and the surrounding soil envelope. The pipe design using the LRFD method is presented. The pipe shall have enough rigidity to withstand the forces that are normally applied during shipment, handling, and installation. Where pipe is to be placed under roads, streets, or freeways, the minimum cover requirements shall be determined. Corrugated steel pipe composed of a smooth interior steel liner and a corrugated steel exterior shell that are attached integrally at the continuous helical lock seam shall be designed as specified. Smooth pipe with ribs shall be designed on the same basis as a standard corrugated steel pipe. Composite corrugated steel pipe of all types shall be designed on the same basis as standard corrugated steel pipe with a curve and tangent profile. Pipe-arch and underpass design shall be similar to round pipe using twice the top radius as the span. The performance of a flexible corrugated steel pipe is dependent on soil-structure interaction and soil stiffness. The construction and installation of corrugated steel pipe and pipe-arches and steel structural plate pipe, pipe-arches, arches, and underpasses shall conform accordingly.
