Preface
This is the tenth edition of CAN/CSA-S6, Canadian Highway Bridge Design Code. It supersedes the previous edition published in 2000, which amalgamated and superseded CAN/CSA-S6-88, Design of Highway Bridges, and the Ontario Ministry of Transportation's OHBDC-91-01, Ontario Highway Bridge Design Code, 3rd ed. Earlier editions of the CSA Standard were published in 1978, 1974, 1966, 1952, 1938, 1929, and 1922. Earlier editions of the Ontario Highway Bridge Design Code were published in 1983 and 1979 by the Ontario Ministry of Transportation.
This Code uses the limit states design approach and reflects current design conditions across Canada as well as research activity since the publication of the previous edition. Several design aspects are addressed for the first time in this edition and a more detailed treatment of many areas is provided. This Code has been written to be applicable in all provinces and territories.
Section 1 (“General”) specifies general requirements and includes definitions and a reference publications clause applicable throughout this Code. It also specifies geometric requirements, based in part on the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads (1999), and hydraulic design requirements, based in part on the Transportation Association of Canada’s Guide to Bridge Hydraulics, 2nd ed. (2001). There are also provisions covering durability, economics, environmental considerations, aesthetics, safety, maintenance, and maintenance inspection access.
Section 2 (“Durability”) addresses durability aspects of materials used in the construction of highway bridges, culverts, and other structures located in transportation corridors. The durability requirements for all of the materials are based on common principles applicable to the deterioration mechanisms for each material, the environmental conditions to which the materials are subjected, and the protective measures and detailing requirements needed to limit deterioration to acceptable levels.
Section 3 (“Loads”) specifies loading requirements for the design of new bridges, including requirements for permanent loads, live loads, and miscellaneous transitory and exceptional loads (but excluding seismic loads). The 625 kN truck load model and corresponding lane load model are specified as the minima for interprovincial transportation and are based on current Canadian legal loads. Ship collision provisions are also included in Section 3.
Section 3 no longer specifies limits on the span lengths for application of the truck and lane loads. Accordingly, long-span requirements have been developed and appear in Section 3 and elsewhere in this Code (these requirements, however, should not be considered comprehensive). Section 3 covers long-span live loading and addresses wind tunnel testing for aerodynamic effects.
Section 4 (“Seismic design”) specifies seismic design requirements for new bridges. These are based primarily on AASHTO (American Association of State Highway and Transportation Officials) LRFDEM-3-M, AASHTO LRFD Bridge Design Specifications, 3rd ed. (2005). Section 4 differs from AASHTO LRFDEM-3-M, however, by providing a more extensive treatment of the importance and response modification factors, new design and detailing requirements for structural steel ductile substructure elements, and design provisions for seismic base isolation. Section 4 also includes design provisions for the seismic evaluation of existing bridges and provisions pertaining to the seismic rehabilitation of existing bridges.
Section 5 (“Methods of analysis”) specifies requirements for analyzing the basic superstructure of a bridge. In its methods for simplified analysis of bridge superstructures, a bridge is treated as a single beam and force effects are averaged over the width of the bridge and subsequently amplified to calculate the true intensity. Distribution factors are based on research conducted up to the late 1990s. Simplified elastic methods are included for the analysis of transverse effects. Refined methods of analysis for short-, medium-, and long-span bridges are also addressed.
Section 6 (“Foundations”) is based, as in the previous edition, on the use of global resistance factors. Section 6 employs the limit states design approach, in which the term “resistance” is applied to the strength or capacity of the soil or rock at the ultimate limit state and the term “reaction” is associated with the serviceability limit state and is indicative of a particular deformation. Section 6 also emphasizes the importance of communication between the bridge structural engineer and the geotechnical engineer at all stages of a project.
Section 7 (“Buried structures”) deals with soil-metal structures with shallow corrugated plates in which thrust is the dominant force in the metal plates as well as soil-metal structures with deep corrugated plates and metal box structures in which flexural effects are also considered in the design of the metal plates. Provisions have been added for reinforced concrete precast and cast-in-place structures, including pipes, box sections, and segmental structures. Section 7 also specifies requirements for determining the properties and dimensions of the engineered soil and non-soil components and addresses construction supervision and construction procedures for soil components.
Section 8 (“Concrete structures”) covers reinforced and partially and fully prestressed concrete components (including deck slabs) made of normal-density, semi-low-density, and high-density concrete of a strength varying from 30 to 80 MPa. Compression field theory is used for proportioning for shear and for torsion combined with flexure. The strut-and-tie approach is used for proportioning regions where the plane sections assumption is not applicable.
Section 9 (“Wood structures”) specifies properties for materials and fastenings that are consistent with CAN/CSA-O86-09, Engineering Design in Wood, and includes data for structural composite lumber. Its provisions related to shear and compression, load distribution, design factors (in many cases), and laminated wood decks are essentially unchanged from those of the previous edition. The shear force concept has been reintroduced for the shear design of sawn wood members and the specified strength values in shear have been increased, in accordance with CAN/CSA-O86-09. In addition, the factors for load-sharing systems have changed.
Section 10 (“Steel structures”) specifies the majority of this Code’s design requirements for steel structures (with the exception of some seismic requirements specified in Section 4). Construction requirements that can have an impact on the resistance factors used in Section 10 are specified in Clause 10.24. Because this Code has been expanded to include long-span bridges, cables and arches are now dealt with. In addition, durability is now addressed much more fully and clauses dealing with beams and girders, composite beams and girders, horizontally curved girders, orthotropic decks, fatigue, and construction have been revised.
Section 11 (“Joints and bearings”) covers the deck joints and bearings most commonly used in Canada.
Section 12 (“Barriers and highway accessory supports”) specifies crash test requirements for barriers and breakaway highway accessory supports. Crash testing may be waived for barrier and accessory support designs that have a successful in-service performance record. Performance levels alternative to those specified in Section 12 are permitted if approved by the regulatory authority.
Section 13 (“Movable bridges”) specifies requirements for the design, construction, and operation of conventional movable bridges. Although the structural design aspects are based on the limit states design approach, the mechanical systems design aspects follow the working stress principle used in North American industry.
Section 14 (“Evaluation”) includes new provisions concerning the three-level evaluation system, evaluation of deck slabs, and detailed evaluation from bridge testing. The provisions on the strength of wood members and the shear resistance of concrete have been improved. Another category of permit vehicle (Permit — Annual or project [PA]) has been added. An optional probability-based mean load method that uses site-specific load and resistance information for more accurate evaluation is also provided. As in the previous edition, a more conventional approach to determining material grades from small samples is used in place of the Baye’s theorem approach in CAN/CSA-S6-88.
Section 15 (“Rehabilitation and repair”) specifies rehabilitation design requirements and provides guidance on the selection of loads and load factors for rehabilitation that is based on the intended use of the bridge following rehabilitation.
Section 16 (“Fibre-reinforced structures”) specifies design requirements for a limited number of structural components containing either high- or low-modulus fibres. The high-modulus fibres (aramid, carbon, and glass) are employed in fibre-reinforced polymers (FRPs), which are used as replacements for steel bars and tendons. The low-modulus fibres are used for controlling cracks in concrete. Section 16 covers concrete beams and slabs, concrete deck slabs, and stressed wood decks. In this edition, Section 16 includes new design provisions that permit glass-fibre-reinforced polymer to be used as primary reinforcement and as tendons in concrete.
Section 17 (Aluminum Structures) specifies the design requirements for aluminum highway and pedestrian structures.
Other new provisions in Section 16 permit the rehabilitation of concrete and timber structures using externally bonded FRP systems or near-surface-mounted reinforcement. The provisions concerning fibre-reinforced concrete deck slabs in the previous edition have been reorganized for this edition to include deck slabs of both cast-in-place and precast construction, which are now referred to as “externally restrained deck slabs”, whereas deck slabs containing internal FRP reinforcement are referred to as “internally restrained deck slabs”. The resistance factors of the previous edition have been revised and depend on conditions of use, with a further distinction made between factory- and field-produced FRPs. The previous edition’s deformability requirements for FRP-reinforced and FRP-prestressed concrete beams and slabs are now dealt with in separate clauses that cover design for deformability, minimum flexural resistance, and crack control reinforcement. The effect of the sustained loads on the strength of FRPs is accounted for in this edition by limits on stresses in FRPs induced at the serviceability limit state. In addition, new stress limits for tendons have been introduced. The design for shear is now an adaptation of this Code’s method for concrete structures and accounts for the decrease in shear carried by the concrete in FRP-reinforced beams. There are also modified provisions for barrier walls.
Funding for developing and publishing this Code was provided by the governments of Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, the Northwest Territories, Nova Scotia, Nunavut, Ontario, Prince Edward Island, Québec, Saskatchewan, and Yukon, Public Works and Government Services Canada, and the Federal Bridge Corporation Limited. This Code could not have been developed without the cooperation of all of these sponsors.
This Code was prepared by the Technical Committee on the Canadian Highway Bridge Design Code, under the jurisdiction of the Strategic Steering Committee on Structures (Design), and has been formally approved by the Technical Committee. It has been approved as a National Standard of Canada by the Standards Council of Canada.
Scope
1.1.1 Scope of Code
This Code applies to the design, evaluation, and structural rehabilitation design of fixed and movable highway bridges in Canada. There is no limit on span length, but this Code does not necessarily cover all aspects of design for every type of long-span bridge. This Code also covers the design of pedestrian bridges, retaining walls, barriers, and highway accessory supports of a structural nature, e.g., lighting poles and sign support structures.
This Code is not intended to apply to public utility structures or to bridges used solely for railway or rail transit purposes.
This Code also does not specify requirements related to coastal effects (e.g., exposure to sea action and icebergs) or to mountainous terrain effects (e.g., avalanches). For structures that can be subject to such effects, specialists need to be retained to review and advise on the design and to ensure that the applicable requirements of other codes are met.
For bridges not entirely within the scope of this Code, the requirements of this Code apply only when appropriate. Necessary additional or alternative design criteria are subject to Approval.
1.1.2 Scope of this Section
This Section specifies requirements for applying the Code and requirements of a general nature for bridges, culverts, and related works. These requirements govern basic geometry and hydraulic design. General requirements are also specified for subsidiary components, deck drainage, maintenance, and inspection access. Broad guidelines related to economic, aesthetic, and environmental considerations are also provided.
1.1.3 Terminology
In CSA Standards, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; “should” is used to express a recommendation or that which is advised but not required; “may” is used to express an option or that which is permissible within the limits of the standard; and “can” is used to express possibility or capability. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.
