Structural Performance of a Full-Depth Precast Bridge Deck System Prestressed and Reinforced with AFRP Bars
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During the last 70 years, corrosion-induced deterioration of bridge concrete decks has resulted in replacement and repair of the deck and a serious need for finding alternative design strategies that would substantially reduce susceptibility of the concrete deck to corrosive environments and the subsequent maintenance cost as well. One alternative is to replace the reinforcing or prestressing steel in concrete with fiber-reinforced polymer (FRP) composite bars, which are corrosion-resistant, and have a very high strength-to- weight ratio. FRP bars can be used as either non-prestressed or prestressed reinforcement. Despite ongoing research mostly focused on prestressed and non-prestressed FRP reinforced concrete beams, less attention has been focused on the structural performance of bridge deck slabs with actual dimensions, boundary conditions, and structural details. Clear understanding of the structural performance and failure mechanism of the bridge deck slab as well as constructability issues are not achievable unless full-scale tests are conducted. The main objective of this research is to establish a design methodology that can be applied to designing a bridge deck system prestressed and reinforced with aramid fiber reinforced polymer (AFRP) bars under service and ultimate loads. The research approach of this investigation consists of conducting an experimental study on a full-scale bridge deck slab including two precast concrete panels prestressed and reinforced with AFRP bars perpendicular to, and parallel to the traffic direction, respectively. The precast panels are connected via a cast-in-place seam (wet joint). In order to gain clearer insight and valid interpretation of the structural performance, the components of the bridge deck are separately tested as well. This includes flexural and shear tests of the cast-in-place panel-to-panel seam, flexural tests of an 1830 mm long strip prestressed with AFRP bars representing the bridge deck section perpendicular to the traffic direction, and flexural tests of an 1830 mm long strip reinforced with AFRP bars representing the bridge deck section parallel to the traffic direction. Once the flexural capacity of the strips and panel-to-panel seam is known, the load capacity of the bridge deck and the corresponding failure mechanism can be better analyzed. Yield line theory, commonly used for analysis and design of steel reinforced concrete slabs, is employed and modified to perform the failure load analysis of the deck slab in spite of the linear and brittle behavior of AFRP bars. Tensile characteristics of AFRP bars are experimentally investigated in the first phase of the project to provide a reliable data set for analytical and experimental studies of the bridge deck system in subsequent steps. Other than the bridge deck slab, this research presents development of a comprehensive computational model for analysis and design of a bridge girder in composite action with the deck slab. To compute the maximum deflection, rational equations based on studying the curvature distribution are derived herein for both prestressed and non-prestressed FRP reinforced concrete beams. The existing deflection equations are typically empirically-derived formulae, which were originally calibrated for steel reinforced concrete beams and hence not suitable for FRP case as the FRP bars have lower modulus of elasticity compared to conventional steel. Consequently, from this research, the structural performance of an AFRP concrete bridge deck slab with full-depth precast prestressed panels is studied and an applicable method for design and failure load analysis is established. Moreover, for FRP reinforced and prestressed concrete beams, two rational deflection equations are developed for suitable design office implementation.
Pirayeh Gar, Shobeir (2012). Structural Performance of a Full-Depth Precast Bridge Deck System Prestressed and Reinforced with AFRP Bars. Doctoral dissertation, Texas A & M University. Available electronically from