INTRODUCTION
Years of dependable service and a multitude of wide ranging installations have led the corrugated steel industry to play a major role in modern engineering technology for drainage systems. Flexible steel conduits play an important role in the form of culverts, storm sewers, subdrains, spillways, underpasses, conveyor conduits, service tunnels, detention chambers and recharge systems; for highways, railways, airports, municipalities, recreation areas, industrial parks, flood and conservation projects, water pollution abatement and many other program

 

Progress Through Research
Engineers and contractors are an imaginative lot, seeking improved ways of designing and building their projects. Steel manufacturers and fabricators have cooperated, through their research and manufacturing staffs, to provide engineers and contractors with better materials, products and installation methods. Manufacturers’ sales staffs and associations are made up largely of experienced professional engineers, knowledgeable in the construction industries problems, who constitute a prime information source on applications, specifications and installation of their products

 

Sizes and Shapes
Corrugated steel products are available in a wide range of sizes and shapes for many applications. Round pipe is available in diameters from 150 mm to nearly 16 m. Pipe-arches, long span structures, arches and box culverts are available in many combinations of rise and span up to 23 m

 

Structural Strength
Mechanical properties of steel are controlled in the mill, and the finished product is fabricated to exacting specifications. The strength and integrity of soil/steel structures is extremely predictable as the result of current research in laboratory and field installations

 

Low Maintenance
Costs of maintaining installations are effectively controlled through modern design criteria for corrosion factors. By proper use of materials for specific locations or applications, utmost economy and optimum service life are assured

 

Time Saving
With the huge investment in equipment and the high cost of labor, contractors are always looking for materials and products to help avoid costly delays and speed installation. Strategically located corrugated steel pipe fabricating plants ensure timely deliveries. Temperature extremes and precipitation have little effect on corrugated steel structures, so they can be scheduled for delivery and installation with a minimum of delay. Rapid installation and the inherent strength of steel enable the contractor to make more efficient use of equipment. Heavy earthmovers can operate over corrugated steel structures with adequate cover, a very real savings often overlooked when evaluating corrugated steel against other materials

 

Acceptance of Steel
Steel is universally recognized, specified and used as a construction material for corrugated conduits and other products. For many years, these products have been included in standards and specifications published by the Canadian Standards Association (CSA), the American Association of State Highway and Transportation Officials (AASHTO), the American Society for Testing and Materials (ASTM), the Federal Highway Administration (FHWA), the American Railway Engineering and Maintenance-of-Way Association (AREMA), the Corps of Engineers, the Federal Aviation Administration (FAA), the U.S. Forest Service, the Natural Resources Conservation Service (NRCS), as well as provincial, county, township and municipal departments, and well recognized consulting engineers

 

STORM DRAINAGE
Generally, drainage facilities can be classified into three major types of construction; culverts, storm sewers and bridges


Culverts
The distinction between culverts and storm sewers is made mostly on the basis of length and the types of inlets and outlets. Aculvert is defined as an enclosed channel serving as a continuation or substitute for an open stream, where that stream meets an artificial barrier such as a roadway, embankment, or levee. Culverts are usually less than 60 m in length. A culvert may also be classified as a type of bridge. Normally, the rigid definition of a bridge requires that the deck of the structure also be the roadway surface, and simply an extension of the roadway. The use of corrugated steel pipe, large diameter pipe-arches, structural plate, and corrugated steel box culverts have played a major role as replacements for deteriorated bridges and altered this conventional definition

chap application

 

Highway 401 in Ontario using spiral rib steel pipe and corrugated steel pipe for median drainage

Storm Sewers and Stream Enclosures
A storm sewer is a collection system for storm water, surface water and street wash, exclusive of domestic and industrial wastes. It is a series of tangent sections with manholes or inlets at all junction points. This water is little, if any, more corrosive than rural watershed runoff. Erosion by the hydraulic traffic may be a factor but normally is less than in culverts

Combination stream crossing (with relief from flow area) and voids to reduce dead load on foundation soils

Corrugated steel storm sewers have a service record of over 100 years. The strength, flexibility, positive joints and installation economies of steel storm sewers are assured by the use of rational corrosion design criteria and readily available coatings and linings. Steel storm sewers are also used to re-line failing sewers of all sizes, shapes and materials with a minimum reduction in waterway area. Many growing communities face the need for expansion in their storm sewer systems to accommodate residential, commercial and industrial developments. Corrugated steel pipe provides a ready solution. Its inherent advantage to contractors, and long range economies for cost-conscious municipalities, enables construction of projects that might not be built otherwise. Open materials competition ensures these communities of the most favorable bid prices possible. The use of corrugated steel pipe for storm sewers has grown. The product data, design information and engineering considerations for such applications are beyond the scope of this publication. The Corrugated Steel Pipe Institute (CSPI) has published a design handbook entitled Modern Sewer Design, which covers proper storm sewer design


Bridges and Bridge Replacements
It is estimated that more than 1/3 of the over 600,000 bridges in North America are in urgent need of repair. This situation is especially acute at county or municipal levels because funds for maintenance and replacement of secondary roadway bridges are limited. The majority of bridges on the secondary system are termed short span, less than 15 m in length, and can be replaced or rebuilt with corrugated steel structures; conventional corrugated steel pipe and pipe arches, structural plate pipe, pipe-arches, arches, steel box culverts, or long span culverts

Long span structure under construction for grade separation

 

LONG SPAN STRUCTURES
In the late 1960's, developments were made which involved adding longitudinal and circumferential stiffening members to the conventional 152 x 51 mm corrugation structural plate structures which permitted the use of larger sizes and increased
permissible live and dead loads. This concept made it possible to achieve clear spans up to 18 m and clear areas up to approximately 100 m2. With the introduction in Canada of 381 x 140 mm deep corrugated structural plate in the 1990's, clear spans increased to 23 m with clear areas of 157 m2. A 400 x 150 mm deep corrugated structural plate product is also available. Long span structures are particularly suited for relatively low, wideopening requirements. Depth of cover generally ranges from 0.3 to 30 m
Design procedures covering these long span structures can be found in the Canadian Highway Bridge Design Code (CHBDC) and the latest editions of the AASHTO Standard Specifications for Highway Bridges, Section 12.7, and LRFD Bridge Design Specifications, Section 12.8. These standards provide for the selection of acceptable combinations of plate thickness, minimum cover requirements, plate radius and other design factors

 

Backfilling adjacent to long-span structure with structural plate ribs

Some of the applications in which these structures are serving include bridges, highway and railroad overpasses, stream enclosures, tunnels, culverts and conveyor conduits. The structures have been extremely popular for bridge replacement, and when used as such provide the following advantages
 Eliminates icy bridge deck problems
 No bridge deck deterioration problems
 Eliminates constant maintenance of bridge approaches and painting of the superstructure
 Permits the use of a constant roadway section in the vicinity of the structure
 The roadway is easily widened by simply extending the ends
 They are readily available and can be field assembled with unskilled labor
 Less design and construction time is required, allowing earlier project completion
 Environmentally preferred since they permit the natural appearance of earth slope and vegetation to be utilized
 Economical
For available shape configurations, sizes and waterway areas, consult Chapter Two, Product Details and Fabrication. If an appropriate structure to meet project requirements is not shown, a design to meet specific site conditions can be provided by the manufacturers