NCHRP Report 549 contains the findings of research performed to develop practical equations for design of shear reinforcement in reinforced and prestressed concrete bridge girders. Recommended specifications and commentary and examples illustrating application of the specifications were also developed. NCHRP Web-Only Document 78 contains Appendices A through J of the final report.
Applying the LRFD shear provisions is difficult for designers. The sectional design model is not intuitively related to physical behavior, and the strut-and-tie model requires several trials to produce an efficient model and does not provide a unique solution. Mechanistic models that can be applied to the shear design of conventional structures and to estimate shear reinforcement requirements in more complex structural configurations are needed. Such tools would permit designers to develop a more intuitive feel for shear reinforcement needs and permit verification of solutions developed from automated design software.
The objective of NCHRP Project 12-61 was to supplement the LRFD methods for shear design with procedures providing a direct solution for transverse and longitudinal reinforcement of concrete structures of common proportions. This work focused on the development of resistance equations that yield unique solutions with defined limits of applicability. The recommended equations are similar in format and application to the resistance equations currently found in the AASHTO Standard Specifications. The equations apply to conventional structure types such as reinforced concrete T-beams, prestressed concrete I girders continuous for live load, prestressed concrete box beams, cast-in-place post-tensioned box girders, hammerhead piers and footings, and multipost reinforced concrete bents and footings.
The link below can be used to download a zip file containing 2 folders, "MathCAD Design Tools" and "Process 12-50". The folder "MathCAD Design Tools" contains a MathCAD program used to calculate the amount of required shear reinforcement at a given section of a reinforced or prestressed concrete beam in accordance with the two proposals of NCHRP 12-61. This program reproduces the results, in a good precision, for Examples 1 and 7 in the Design Examples in Appendix J (Web Only Document 78). This material is mainly intended for users with MathCAD installed on their computer, but one example can be viewed as an HTML file.
The material in the folder "Process 12-50" is described in Appendix I: Utilization of the Process 12-50 ( NCHRP Web-Only Document 78). Additional information on the application of "Process 12-50 can be found in NCHRP Report 485.
Database and Design Tools (ZIP, 20.8 MB)