New extended grillage methods for the practical and precise modeling of concrete box-girder bridges

The Hambly plane grillage method has been regarded as one of the classic numerical methods in the design field for modeling wide box-girder bridge structures. However, when it comes to the in-depth design applications, its strict division rules and insufficient mechanical explanations often make engineers inconvenient or puzzled at bridge modeling. This article investigates whether this method may be extended to become more adaptable for the design of current concrete box-girder bridge structures in consideration of both convenience and precision. To this end, the defects of Hambly plane grillage method are recognized, and new extended grillage methods, including the single-layer folding surface grillage and spatial grillage, are proposed respectively, to deal with different bridge design objects completely in a beam-oriented environment. The former allows freer cross-sectional division by breaking the basic rule of Hambly plane grillage method to include longitudinal separate-type beam components for a better exhibition of shear lag effects. The latter emphasizes a complete consideration of spatial behavior, including the easily missed in-plane effects of the top and bottom plates. The effectiveness of the methods are demonstrated by comparison case studies in some benchmark models and by a discussion of their applications.