Some aspects of the limit state design for concrete in the new highway bridge design specification

A unified concrete bridge design specification is being prepared concurrently with the unified concrete structures code being produced by the Standards Association of Australia and it is anticipated it will be issued in 1985. The NAASRA concrete working group has worked in close cooperation with the SAA committee to achieve compatibility between the two codes. Aspects of the new concrete design specification are outlined. Major changes to the specification occur with the change to limit state format and the integration of reinforced, partially prestressed and prestressed concrete into one section. Requirements for durability are substantially amplified with exposure classified according to atmospheric conditions and special conditions or structural application and requirements given for different classifications. Some of the serviceability requirements are presented as is an outline of the calculations for strength of beams in shear and for the strength of columns. Finally two design examples are presented which show that there is considerable variability between the results obtained using different criteria but complying with the existing design specification (a).