Research On The Flexural Behavior Of Self-compacting Reinforced Concrete Bridge Deck Slabs With GFRP Bars

In a harsh external environment,the service life of traditional reinforced concrete structures is often shortened due to the corrosion problem of steel bars.It will cause the cracking and stripping of the concrete material shift into an earlier moment,and produces potential safety hazards existed in bridge structures.At such situations,the fiber reinforced polymer(FRP)bars are recommended in these new building components due to their perfect advantages in corrosion resistance,high tensile strength and light weight.In addition,the conventional cement-based concrete material also has many disadvantages such as highenergy consumption and cost,together with the difficulty of vibration.At this time,using highvolume fly ash self-compacting concrete(HVFA-SCC)can efficiently avoid those shortcomings and thus provides a new direction for sustainable construction.Bridge deck slabs constructed by above Glass Fiber Reinforced Polymer(GFRP)and HVFA-SCC are featured by low energy consumption,environmental protection and high durability.However,currently existing research focused on the flexural performance of such bridge deck slabs is still very limited.This greatly restricts the wide application of this new components in practical civil engineering.Thus,the purpose of this master thesis is to systematically document the flexural behaviors of HVFA-SCC bridge deck slabs reinforced by GFRP bars.The main works and findings of this paper can be summarized as follows:(1)Slump,compressive strength,elastic modulus and splitting tensile strength of HVFASCC were regularly recorded.And microscopic test techniques including scanning electron microscope(SEM)and energy disperse spectroscopy(EDS)were adopted to observe the microstructures of at different ages.In addition,relations between the macroscopic properties and the microscopic characteristics of the HVFA-SCC were also built.Test results show that:(a)Early high temperature curing can significantly improve the compressive strength,splitting strength and elastic modulus of HVFA-SCC materials.(b)Scanning electron microscopy(SEM)and energy disperse spectroscopy(EDS)confirm that the early strength and late strength of HVFA-SCC materials are not easy to be reduced under a high temperature curing condition.(2)Four-point bending test on 11 bridge deck slabs was carried out to analyze the failure mechanism of GFRP reinforced HVFA-SCC members.together with the normal service load under the control of different parameters were investigated.The influences of concrete material types(PC and HVFA-SCC),reinforcing bar diameter,reinforcing bar type,longitudinal reinforcement ratio and shear span ratio on the behavior of HVFA-SCC bridge deck slabs reinforced with GFRP bars were also discussed.The results show that:(a)Initial crack width and extending height are usually large,and the deflection changes significantly after cracking.(b)Increasing the reinforcement ratio of the bridge panel or using CFRP bars can significantly improve the member's initial stiffness,but also increase the crack number in the later period.(c)The surface treatment of bars has an significant effect on the bar's midspan strain.When the friction coefficient is larger,the strain notably decrease.The ratio of reinforcement is also negatively correlated with the mid-span strain.(3)Test results including characteristic bearing capacities,deformations and cracking features of the eleven bridge deck slabs members were compared with available models proposed by specifications and scholars.The applicability and accuracy of the existing models for the GFRP reinforced HVFA-SCC flexural members were then analyzed.Test results show that:(a)Most of the existing formulas fouced on the shear capacity of FRP reinforced concrete beams underestimate the ultimate bearing capacity of bridge panels.(b)The predictive formula of average crack spacing proposed by Farra B can well predict the crack spacing of all bridge panels,while the expressions proposed by ACI 440.1R-0.6 and EHE to caluculate the maximum crack width can well predict the crack width of bridge panels in this paper(4)Finite element simulations on GFRP reinforced HVFA-SCC bridge deck slabs were carried out.The validation and accuracy of the established finite element model were firstly checked with the test results.Numerical results show that the finite element modelings of GFRP reinforced SCC bridge deck slabs has a good simulation effect.