The application of fiber reinforced plastic（FRP）,including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally b...The application of fiber reinforced plastic（FRP）,including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement（EBR） and near-surface mounted（NSM） strengthening techniques.This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC beam.Since there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height（h 0） of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of the FRP and steel rebar satisfies the equation：ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.展开更多
Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain...Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain coordination results of 34 reinforced concrete beams(four groups)strengthened with different methods were presented including external-bonded or near-surface mounted glass or carbon FRP or helical rib bar in order to study the strain coordination of the strengthening materials and steel rebar of RC beam.Because there is relative slipping between concrete and strengthening materials(SM),the strain of SM and steel rebar of RC beam satisfies the double linear strain distribution assumption,that is,the strain of longitudinal fiber parallel to the neutral axis of plated beam within the scope of effective height(h0)of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of SM and steel rebar satisfies the equation εGCH=βεsteel,where the value of β is equal to 1.1-1.3 according to the test results.展开更多
The characteristic of near-surface microstructure and its effects on the torsion performance of cold-drawn pearlitic steel wires for bridge cables were investigated by focused ion beam-scanning electron microscope,tra...The characteristic of near-surface microstructure and its effects on the torsion performance of cold-drawn pearlitic steel wires for bridge cables were investigated by focused ion beam-scanning electron microscope,transmission electron microscopy and differential scanning calorimetry.The samples with similar tensile strength before and after hot-dip galvanizing process are,respectively,characterized as delaminated and non-delaminated in torsion test which indicates that the tensile strength is independent of the toughness value(i e,reduction area and torsion ability).It is interesting to find that there exists submicron granular ferrite on near-surface of the wires,which can be attributed to dislocation rearrangement and sub-grains rotation during cold drawing and hot-dip galvanizing process.And their distribution can suggest homogeneousness of deformation degree to a certain extent:the closer to the surface of their distribution,the more homogeneous deformation of the wires.There is a close relationship between the thermal stability of the cementite layer and distribution of granular ferrite:differential scanning calorimetry(DSC)analysis shows that the sample is accompanied by submicron granular ferrite which is located closer to the surface has higher thermal stability under galvanizing temperature(450°C).A new mechanism of the torsion delamination of pearlitic steel wires is discussed in terms of the thermal stability of the cementite layer and distribution of granular ferrite.展开更多
基金Consultative Program of the Chinese Academy of Engineeringthe foundation for Excellent Young of Hunan Scientific Committee+1 种基金the National Natural Science Foundation of Hunan Provincethe Science and Research Program of Hunan Province
文摘The application of fiber reinforced plastic（FRP）,including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement（EBR） and near-surface mounted（NSM） strengthening techniques.This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC beam.Since there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height（h 0） of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of the FRP and steel rebar satisfies the equation：ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.
基金Project(11B033)supported by the Foundation for Excellent Young Scholars of Hunan Scientific Committee,ChinaProject(116001)supported by the Consultative Program of the Chinese Academy of Engineering+1 种基金Project(11JJ6040)supported by the National Natural Science Foundation of Hunan Province,ChinaProject(2010GK3198)supported by the Science and Research Program of Hunan Province,China
文摘Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain coordination results of 34 reinforced concrete beams(four groups)strengthened with different methods were presented including external-bonded or near-surface mounted glass or carbon FRP or helical rib bar in order to study the strain coordination of the strengthening materials and steel rebar of RC beam.Because there is relative slipping between concrete and strengthening materials(SM),the strain of SM and steel rebar of RC beam satisfies the double linear strain distribution assumption,that is,the strain of longitudinal fiber parallel to the neutral axis of plated beam within the scope of effective height(h0)of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of SM and steel rebar satisfies the equation εGCH=βεsteel,where the value of β is equal to 1.1-1.3 according to the test results.
基金Funded by the National Key R&D Program of China(No.2017YFB0304801)。
文摘The characteristic of near-surface microstructure and its effects on the torsion performance of cold-drawn pearlitic steel wires for bridge cables were investigated by focused ion beam-scanning electron microscope,transmission electron microscopy and differential scanning calorimetry.The samples with similar tensile strength before and after hot-dip galvanizing process are,respectively,characterized as delaminated and non-delaminated in torsion test which indicates that the tensile strength is independent of the toughness value(i e,reduction area and torsion ability).It is interesting to find that there exists submicron granular ferrite on near-surface of the wires,which can be attributed to dislocation rearrangement and sub-grains rotation during cold drawing and hot-dip galvanizing process.And their distribution can suggest homogeneousness of deformation degree to a certain extent:the closer to the surface of their distribution,the more homogeneous deformation of the wires.There is a close relationship between the thermal stability of the cementite layer and distribution of granular ferrite:differential scanning calorimetry(DSC)analysis shows that the sample is accompanied by submicron granular ferrite which is located closer to the surface has higher thermal stability under galvanizing temperature(450°C).A new mechanism of the torsion delamination of pearlitic steel wires is discussed in terms of the thermal stability of the cementite layer and distribution of granular ferrite.
