Experimental Research on Bond Properties between FRP Rebar and Concrete under the Effect of Ocean Tide
|Course||Bridge and Tunnel Engineering|
|Keywords||FRP rebars wedge-type anchors finite element the tidal wet and dry cycle bond-slip pull-out test numerical simulation|
Bonding performance of concrete and fiber reinforced plastic (FRP) rebars will directly affect its long-term performance, the experimental study at this stage is mainly on the type of FRP rebars, the bond length of FRP rebars, the diameter of the FRP rebars, the surface shape of FRP rebars and the strength of concrete to analyse the change of long-term bonding properties of FRP rebars and concrete, but for the role of the external environment, especially the effect ofocean salinity and tidal cycle on bonding performance has not been taken seriously. The serious degradation of reinforced concrete durability caused by the high erosion environment inoffshore and coastal areas is one of the most important reasons for using FRP rebars instead of steels. Although the durability test for FRP rebars at present has taken the influence of erosion environment into consideration, the bonding performance of FRP rebars and concrete in erosion marine environment has not been reported. Compared with the Marine atmospheric environment and Marine underwater environment, the wet-dry alternation of ocean tides environment will have a significant effect on concrete pore structure, the durability of FRP rebars and the degradation of bonding properties between concrete and FRP rebars.1. Based on the experimental information such as ultimate load and slip value achieved from the test investigation of wedge-type anchor for FRP rebars, three-dimensional finite element model is established. Non-linear stress analysis for anchorage system is carried out by the method of numerical simulation. Model analysis and benchmark test show high consistency and accuracy on the dynamic evolution process of slip, the failure form and the experimental values. Because of the limitation of the scale, the tested parameters can not meet the needs of the anchorage design for FRP rebars. Stress analysis of wedge-type anchors is analyzed by FEM method, and the parameter effects on anchorage, such as the taper of anchor-ring, angle difference between barrel and wedge, thickness of aluminum sleeve, presetting load level, initial contact position between barrel and wedge, length of the anchorage and so on, are analyzed. The recommend range for these parameters are confirmed by numerical analysis in order to provide reference to design and improvement of wedge-type anchors.2. In this test, the seawater sample solution is based on the salinity of seawater which is achieved from engineering investigation,by adding solution of different salinity,74pull-out test specimens with FRP rebars and36cubes are produced.To simulate the ocean tidal environment,we make the concrete bonding specimens under the dry-wet alternate conditions of a certain salinity solution.We test the pull-out curves of the specimens under different tidal cycle at the aim of achieving the degradation law of the bonding performance of FRP rebars and concrete.3.Based on this test and experimental research presented, degradation theoretical model about bond stress-slip curves of BFRP rebars and concrete is proposed. This model is used to compare with experimental bond stress-slip curves. It is proved that model curve gets good agreement with the experimental curve. At the same time, the numerical simulation of pull-out test specimens with BFRP rebars are conducted with the ANSYS program. The methods and skills of nonlinear BFRP numerical simulation by ANSYS program used in concrete structures are summarized and presented. Using ANSYS program finite element software for numerical simulation of will test bond-slip relationship between the curve and the numerical simulation of bond-slip relationship between the curve compared to the model under different loads at different locations of the spring force of spring element,slip and the stress of FRP rebars analysis software ANSYS to verify the correctness of the results of numerical simulation.