Study On The Properties Of Damage Development And Accumulation Of BFRP Confined HRBF500 RC Column Under Low- Cycle Fatigue Load

The ends of concrete columns are prone to yield to plastic hinge zone under fatigue loads such as seismic process due to lacking of lateral restraint. The decrease of strength and stiffness of concrete columns, along with the loss of bearing capacity, indicates the plastic deformation increases with the load cycles. When the plastic deformation develops to a certain limit, the structure collapses. HRBF500 steel bar has a satisfying performance in plasticity and toughness because of high strength and good ductility. Comparing to other fiber materials, BFRP has better properties and lower price, as well as more advantages that are widely considered in research and engineering. However, the properties of damage development and accumulation of BFRP confined HRBF500 reinforced concrete columns have not been researched.This paper presents the experiment of 5 BFRP confined HRBF500 reinforced concrete columns under axial load and cylic lateral loads. Some factors were analysed on the influence of the seismic behavior, ductility and strength of the columns, such as the way BFRP was used and the displacement amplitudes. The results showed that BFRP effectively improved the members’ hysteretic performance and slowed the degradation of strength and stiffness. The displacement amplitudes showed a siginificant effect on the damage accumulation of members. BFRP worked by providing confining pressure and a boundary decreasing effect was found on the number of BFRP layers.The software ABAQUS was used for nonlinear finite element analysis of the test of concrete columns and the simulation results were in good agreement with the experimental results. The PEEQ and stress distribution were consistent with test phenomena.Based on the classic double parameters damage model Park-Ang, a fixed damage modle was established for BFRP confined HRBF500 reinforced concrete columns. The new model considered the influence of the accumulated hysteresis dissipated energy in different displacement amplitudes and the styles BFRP confined. The evaluation criteria of damage index was given for the BFRP confined HRBF500 reinforced concrete columns.On the basis of the research, design suggestions and problems to be solved were given.