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Evaluation of Load Distribution Factor by Series Solution for Orthotropic Bridge Decks |
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| Authors: | Bin Zou Julio F. Davalos An Chen Indrajit Ray |
| Affiliation: | 1Structural Engineer, East China Architectural Design and Research Institute (ECADI), 151 Hankou Rd., Shanghai, China, 200002; formerly, Graduate Research Assistant, Dept. of Civil and Environmental Engineering, West Virginia Univ., Morgantown, WV 26506-6103. 2Benedum Distinguished Teaching Professor, Dept. of Civil and Environmental Engineering, West Virginia Univ., Morgantown, WV 26506-6103. E-mail: julio.davalos@mail.wvu.edu 3Research Assistant Professor, Dept. of Civil and Environmental Engineering, West Virginia Univ., Morgantown, WV 26506-6103 (corresponding author). E-mail: an.chen@mail.wvu.edu 4Research Associate Professor, Dept. of Civil and Environmental Engineering, West Virginia Univ., Morgantown, WV 26506-6103. |
| Abstract: | In bridge engineering, the three-dimensional behavior of a bridge system is usually reduced to the analysis of a T-beam section, loaded by an equivalent fraction of the applied live load, which is called the live load distribution factor (LDF). The LDF is defined in the both the AASHTO Standard Specifications and the LRFD Specifications primarily for concrete slabs and has inherent applicable limitations. This paper provides explicit formulas using series solutions for LDF of orthotropic bridge decks, applicable to various materials but intended for fiber-reinforced polymer (FRP) decks. The present formulation considers important parameters that represent the response characteristics of the structure that are often omitted or limited in the AASHTO Specifications. A one-term series solution is proposed based on the macroflexibility approach, in which the bridge system is simplified into two major components, deck and stringers. The governing equations for the two components are obtained separately, and the deflections and interaction forces are solved by ensuring displacement compatibility at stringer lines. The LDF is calculated as the ratio of the single stringer interaction force to the summation of total stringer interaction forces. To verify this solution, a finite-element (FE) parametric study is conducted on 66 simply supported concrete slab-on-steel girder bridges. The results from the series solution correlates well with the FE results. It is also illustrated that the series solution can be applied to predict LDF for FRP deck-on-steel girder bridges, by favorable comparisons among the analytical, FE, and testing results for a one-third-scale bridge model. The scale test specimen consists of an FRP sandwich deck attached to steel stringers by a mechanical connector. The series solution is further used to obtain multiple regression functions for the LDF in terms of nondimensional variables, which can be used for simplified design purposes. |
| Keywords: | Load distribution Fiber reinforced polymer Bridges, concrete Bridge decks Plates Finite element method Regression analysis |