A simplified method to develop LRFD preliminary design charts for prestressed concrete bridges

The 2011 PC! Bridge Design Manual provides preliminary design charts for selecting the girder size and number of prestressing strands for a given span length and beam spacing but only for fc = 8,000 psi (55.2 MPa). This single strength limits the use of the charts, particularly for states considering ultra-high performance concrete (UHPC). Accordingly, this dissertation presents a simplified procedure to develop preliminary design charts for prestressed concrete bulb-tee girders considering service load stress limits, flexural strength and stresses at release. The results for a BT-72 beam are first compared with the 2003 PC design charts originally developed based on the AASHTO Standard Specifications. The procedure is then adapted to the AASHTO LRFD Bridge Design Specifications and verified with the prevailing 2011 PC!I design charts. Finally, new LRFD charts are generated for normal strength concrete (NSC), high performance concrete (HPC), and ultra-high performance concrete (UHPC) with 0.5, 0.6, and 0.7-in. (13, 15 and 18 mm) strands for simple and two-span continuous bridges to illustrate the simplified procedure and potential impact of UHPC, larger strand size, and continuity on bridge girders.