Research On Seismic Behavior Of Ultra High Performance Fiber Reinforce Concrete Joint

The purpose of this work is to study the seismic performance and shear strength of UHPFRC beam-column joints(ultra-high performance fiber reinforced concrete).Finite element tests were performed on three UHPFRC beam-column joints;the properties of the specimens were inspected,including failure process,shear deformation,stirrups and longitudinal reinforcement ratios,load transfer and bearing capacity.The influence of the joint type,the axial compression load level of the joint core and the stirrup ratio on the failure mode and the joint shear strength is analyzed.The shear strength mechanism of reinforced UHPFRC beam-to-column joint includes diagonal brace and truss mechanism.The role of steel fibers through cracks is similar to that of steel bars in the truss mechanism.Based on test results,Finite element models predict the shear strength of UHPFRC composites.An experimental test results UHPFRC joints for different fiber contents was done by Patricia A.Sarmiento and Benjamin Torres fro university of Columbia.Their experimental results was used as a validation data for this paper’s FEA models.The brittleness of the joint area will affect the ductility design concept and the expected overall performance of the structure under seismic loads.In view of the importance of the influence of joint shear failure on the strength,ductility and stability of UHPFRC flexural frame,this paper proposes a finite element modeling method focusing on FEA models.A non-linear(FEA)of the UHPFRC joint carried out a study on shear capacity,deformation and crack mode of the joint to check the shear failure mode of the joint.Using the 3D finite element model,it is possible to properly model the stress-strain behavior of concrete,tensile cracks and compression damage in concrete,and indirect modeling of steel-concrete connections.Research publications analyzing bond slip,steel rebar and stirrup interaction with the concrete matrix was introduced in Chapter 4 to provide more information on bond behaviour between steel and concrete.