Papers by Keyword: Concrete Deck

Abstract: The present study investigated the effects of shear slip on the deformation and strength of FRP-concrete composite beams. The load-slip curves were found consisting of two phrases: load kept increasing without any interfacial slip in the former phrase and load went up linearly versus interfacial slip in the latter phrase. A bilinear interfacial model was therefore proposed to describe the function between interfacial shear force and slip in FRP-Concrete composite beams. Two dominant parameters in the model, initial bond stress (v_s) and shear stiffness of the interface (k), were defined according to the testing data. Initial bond force is the shear force when slip occurs; shear stiffness is the ratio of load increase versus interfacial slip. This new model can be applied to predict the stiffness and analysis stress of the composite beam considering the effect of slip.

Abstract: This paper describes the structural forms for hybrid FRP-concrete highway bridge deck. This bridge deck is applid in a project, which involved the implement of FRP-concrete deck over prestress concrete girders. In this project three forms of FRP reinforcing were combined to reinforce the concrete deck. This paper introduced another stiffened FRP deck panels connecte with the FRP composite girders in the steel-free FRP-composite modular bridge system. It is shown that the combination of FRP meterial and concrete for bridge deck is recommended in the design of highway bridge.

Abstract: To avoid the creep rupture of GFRP bar in RC members, not exceeding 20% design tensile strength (ffu)) is recommended as design limit for sustained stress level in GFRP bar in current ACI 440.1R-06 guideline. In this paper, the effects of using light weight concrete (LWC) is studied to investigate the sustained stress level in GFRP bar RC bridge decks by a parametric study. Results show that the sustained stress in GFRP bar in LWC bridge decks is in between 2.8-5.7% of ffu, while it is about 3.44-7.52% for normal weight concrete (NWC) deck.

Abstract: In current ACI 440.1R-06 design guideline, an environmental reduction factor (ERF) is specified to account for long-term durability of GFRP bar used in reinforced concrete structures. Such ERF factor is still lack of confidence to concrete industry prior to deliberate calibrations with in-field real time data. In this paper, a parametric study on the design of GFRP bar RC bridge deck per ACI 440 guideline is presented to investigate the stress level in GFRP bar under ultimate design loads per AASHTO LRFD Specifications. Results show that tensile stress in GFRP under ultimate design loads is always less than 25% of GFRP guaranteed tensile strength f*fu, which is much lower than the design strength per as specified in ACI 440 Guideline (i.e., 0.7 f*fu). It showed that GFRP bar RC bridge deck as designed in accordance with ACI 440 guideline could give sufficient safety margin.

Abstract: This paper presents the investigation of sustained stress level in GFRP bar used as main reinforcement in typical reinforced concrete bridge deck, which is often subject to severe environmental exposures in North America. AASHTO LFRD approach is used for the design of GFRP RC deck that also meets with the requirements per as specified in ACI 440.1R-06. Research results show that the sustained stress level in GFRP bar varies in the range of approx. 3% -7% for bridge deck with various deck thickness and girder spacing.

Abstract: Based on a nationwide survey and deck inspection in Michigan, the phenomenon of more severe corner cracking on skewed bridge decks was commonly observed. A series of FEA by DIANA were carried out to identify the possible causes and viable cures for such cracking. Prior to the FEA, the accuracy of FEM modeling was calibrated by two skew bridge decks instrumented using temperature and strain sensors for the deck concrete and the ambient environment. Test and FEA results found that the cracking has been mainly caused by thermal and shrinkage stress, and that possibly propagated and worsened by repetitive truck wheel loading. According to current Michigan practice of skew deck design and construction, additional reinforcement in the corner areas is therefore recommended to reduce concrete stresses. Further research is also recommended to develop solutions using optimal combinations of ingredients in concrete and to minimize the constraint between the deck and the supporting superstructure.