Nominal Flexural Strength of Conventional or Hybrid Composite Girders

This paper contains a parametric study for the development of the nominal flexural strength of conventional composite girders and hybrid composite girders using HSB high-performance steels in positive bending region. The flexural strength and the ductility of a wide range of conventional or hybrid composite girders are calculated using moment-curvature analysis, and the plastic moment of each section is obtained using simple plastic theory. For developing new design equations, the obtained flexural strength and the ductility of conventional or hybrid composite girders are compared to the previous research work and the current AASHTO LRFD's design equations. The comparison results show that there are considerable differences in flexural strength distribution between the conventional composite girders and the hybrid composite girders. It was also observed that in case of the hybrid composite girders, until considerably high ductility parameter, the flexural strength is not smaller than the plastic moment. Based on the results of parametric study, new design equations are proposed for predicting the nominal flexural strength of conventional or hybrid composite sections.