Structural performance and design evaluation of HPS 70W bridge girders

An evaluation of the behavior of bridge girders containing HPS 70W high performance steel is conducted. The basis for this study is a three-span replacement bridge in Gaffney, South Carolina which utilizes HPS 70W girders within all negative moment regions. The study consists of in-situ measurements, which are currently in progress, experimental tests, and analytical investigations. Three half-scale specimens, each with different bracing and stiffener configurations, are tested in the structures laboratory at USC under monotonic and cyclic loading conditions. This paper presents results from analytical and experimental investigations and focuses on the strength performance of the girders. Studies on fatigue performance and in-situ measurements and long term monitoring are the subjects of subsequent papers. Data obtained from laboratory tests is used for the evaluation of the structural performance and the calibration and validation of computer models for design evaluations. Parametric studies through computer simulations are conducted to evaluate alternate designs. The findings of this study indicate that improved structural performance may be obtained when location of bracing is optimized and fabrication imperfection tolerances are minimized. Furthermore, the findings indicate that a similar level of structural performance at reduced cost is achieved when hybrid designs are specified in place of homogeneous HPS 70W cross sections.