Partial Interaction Shear Flow Forces in Continuous Composite Steel–Concrete Beams

Most research since the introduction of mechanical forms of shear connection to provide interaction in steel–concrete beams in the 1940s has focused on simply supported beams. With the use of advanced computer techniques current research on continuous beams is increasing and tends to focus on design issues. However, the fatigue assessment of existing composite bridges worldwide is growing rapidly due to increasing allowable load limits and because many of the bridges are reaching the end of their originally anticipated design life. Based on linear elastic partial interaction theory, this paper develops simplified equations and practical assessment charts that are used to more accurately assess the remaining strength or endurance of the shear connection in continuous composite beams. This research extends the tiered assessment approach previously published for simply supported beams so that it is now applicable to composite beams with any number of spans, varying span lengths and varying shear connection distribution, and/or cross-sectional geometry. The technique is validated using a finite element program developed to model the behavior of composite structures and an example application in a fatigue assessment is given.