Abstract
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.
Scope
1.1 This practice covers the structural design of 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. Ribbed and composite ribbed steel pipe, ribbed pipe with metallic-coated inserts, closed rib steel pipe, and composite corrugated steel pipe shall be of helical fabrication having a continuous lockseam. This practice is for pipe installed in a trench or embankment and subjected to earth loads and live loads. It must be recognized that a buried corrugated steel pipe is a composite structure made up of the steel ring and the soil envelope, and both elements play a vital part in the structural design of this type of structure. This practice applies to structures installed in accordance with Practice A798/A798M or A807/A807M.
1.2 Corrugated steel pipe and pipe-arches shall be of annular fabrication using riveted or spot-welded seams, or of helical fabrication having a continuous lockseam or welded seam.
1.3 Structural plate pipe, pipe-arches, underpasses, and arches are fabricated in separate plates that, when assembled at the job site by bolting, form the required shape.
1.4 Deep corrugated plates are covered in this standard as a means of providing design properties only. The structural design of deep corrugated structures is not supported by this standard.
1.5 This specification is applicable to design in inch-pound units as A796 or in SI units as A796M. Inch-pound units and SI units are not necessarily equivalent. SI units are shown in brackets in the text for clarity, but they are the applicable values when the design is done per A796M.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
