Shear Design Considerations for Deep Concrete Bridge Girders

摘要

Five specific limitations to the existing shear design methodologies of the AASHTO LRFD Bridge Design Specifications and ACI 318-08 are discussed: (1) the issues resulting from the fact that what has been tested in the laboratory is not representative of what is built in the field for bridge structures and therefore where additional laboratory testing is needed particularly for bridge members; (2) the equivalency and non-equivalency of the treatment of axial load and prestress in shear provisions; (3) the basis for the minimum and maximum shear reinforcement requirements or limits for members and why those requirements differ in the AASHTO LRFD Specifications from those in ACI 318-08; (4) shear design considerations for the end regions of bridge girders and the need to design for the effects of the funneling of the shear force into the support and the balancing of the tension caused by shear at the face of the support; and (5) the relative variations in the components of the shear resistance with increasing load and changes in member behavior and the significance of those variations for the limitations to the existing shear design concepts of the AASHTO LRFD Specifications and ACI 318-08.