UNIFIED BENDING STRENGTH DESIGN OF CONCRETE MEMBERS - AASHTO LRFD CODE

This paper summarizes the procedure for the computation of nominal ben ding resistance of reinforced, prestressed, and partially prestressed concrete members according to the 1994 ''AASHTO LRFD Specifications fo r Highway Bridge Design.'' The cases of rectangular or flanged section s, underreinforced or overreinforced, with a combination of reinforcin g bars and prestressing tendons, whether bonded or unbonded, are cover ed. Provisions on limiting the flexural reinforcement adopted in the n ew specifications are summarized. They address minimum and maximum lev els of reinforcement in flexural members, the percent of moment redist ribution in continuous bending members, and the prediction of stress a t ultimate in bonded and unbonded tendons. The provisions are nondimen sional and can be applied to any code. Logical flowcharts showing the various computational steps are provided, and examples illustrating th e procedure are developed.