Intrinsic method of effective flange width evaluation for steel-concrete composite bridges

This study has focused on developing a more versatile approach for evaluating the effective flange width (beff) in steel-concrete composite bridges. The concept of effective flange width is very important for a simplified structural analysis, especially for computing stresses and displacements. Therefore, the accuracy of effective flange width has a major impact on the design of structural components. In this dissertation, two effective flange width definitions for steel-concrete composite bridges were developed for positive and negative moment sections. The definitions could be applied to both interior and exterior girders, as well as serviceability and strength limit states. This study mainly focused on an analytical work based on finite element method (FEM) to extract effective flange width provision. A finite element modeling scheme was rationalized and successfully verified with several independent experimental studies. All FEM analyses were conducted using ABAQUS. To develop effective flange width design criteria, a parametric study was performed. The configurations of simple span and multiple span continuous steel-concrete composite bridges were rationally selected according to design of experiments concepts. Three main parameters were identified to have the most influence on effective flange width, which were span length ( L), girder spacing (S), and skew angle (theta). Statistical regression analysis was employed to generate a series of candidate design equations based on different combinations of parameters. All of the equations were successfully validated against bridges outside the parametric study boundary. The influence of negative shear lag on effective flange width of composite bridges was investigated. The results showed an insignificant effect of negative shear lag on the proposed effective flange width criteria.