APPENDIX F – MODELING ASSUMPTIONS（附录F 建模假设）.pdfVIP

APPENDIX F – MODELING ASSUMPTIONS F-1 Steel I Sections, Cast-In-Place Concrete Tee Beams, Concrete I Sections and Bulb Tee Sections (AASHTO Types A, E, K) These slab-on-girder section types are modeled using standard grillage techniques. All elements are modeled using a basic three-dimensional frame element. Bridges of types a and k are assumed to be composite. The section properties of the longitudinal girders are computed using the material properties of the deck. The composite area, moment of inertia, and torsional constant are computed for the girder and then transformed to the deck material by multiplying them by the modular ratio. The moment of inertia is computed considering the composite neutral axis and the parallel axis theorem. These values are then output to the grillage model. For the concrete tee beams (type e), the sections properties for the beams are simply computed and used. The deck elements properties are computed based on a tributary area approach. Each deck element is assumed to have the height of the deck thickness and the width of half the deck element spacing on each side of the element being considered. For type e bridges, the deck element properties are computed using the thickness of the top flange of the tee section. Cast-In-Place Multicell Box Beams (AASHTO Type D) The grillage analysis of cast-in-place multicell box beam bridges is based on the work of Song, et al (120). A method for modeling these types of bridges using a grillage method is outlined in this paper and summarized here. A grillage model was compared with a finite element model using shell elements for all member components. It was shown that the bending moment from the grillage