Experimental Study On Behavior Of RC Columns Reinforced With FCCC-R Under Combined Compression And Bending

In the May 12th wenchuan earthquake and the April 14th yushu earthquake,the homes that people rely on for survival collapsed in just a few minutes.The destruction of the structural column is one of the important reasons leading to the destruction and collapse of the whole structure.RC columns reinforced with FCCC-R is a novel type of composite member proposed in recent years.Concrete filled FRP tubes are used as the confined core in RC columns.The confining effect of FRP tube on concrete is used to improve the compressive strength of internal concrete.Apart from this,the combined confining effect of FRP tube and concrete on rebars is used to limit the buckling of rebars,so as to make full use of the compressive bearing capacity of high-strength rebars.Thus,the ultimate collapse resistant capacity of structural columns can be improved.However,the applicability of axial compression in real life is very low.For a variety of reasons,the structural columns in most buildings are not fully axial compression.Eccentric compression members are the most common members,so it is necessary to study the mechanical behavior of RC columns reinforced with FCCC-R under combined compression and bending.In order to study the eccentric compressive behavior of RC columns reinforced with FCCC-R,10 specimens（7 RC columns reinforced with FCCC-R and 3 RC columns）were designed and fabricated in this paper,and the static loading test of eccentric compression was carried out.The failure modes of the specimens,the load-lateral deflection curves and axial strain distribution curve were observed during the experiment.Based on the experimental results,the influence of eccentricity on the bearing capacity,ductility and flexural stiffness of the novel columns were analyzed.The experimental findings include:（1）The ultimate failure pattern of RC columns reinforced with FCCC-R was that concrete was crushed at the compression side and the horizontal cracks were distributed in the tension side.（2）Before peak load,the strain distribution of the hybrid column satisfies plain-section assumption.FCCC-R works well with external reinforced concrete.（3）The flexural stiffness at the peak point of RC columns reinforced with FCCC-R is increased to different degrees.However,as the eccentricity increases,the amplitude of improvement decreases.（4）For large eccentricity,the stiffness and peak bearing capacity of RC columns reinforced with FCCC-R are improved.After the peak point,the bearing capacity of the hybrid column decreases slowly,and it has stable residual bearing capacity and residual deformation capacity.For boundary and large eccentricity,the peak load and lateral deformation of hybrid column are lower than RC column.（5）With the increase of eccentricity（0）),the peak bearing capacity()of RC columns reinforced with FCCC-R decreases,the lateral deflection of peak point(₈))increases and ductility decreases.（6）The structural form of RC columns reinforced with FCCC-R should be reasonably designed in order to enable the mechanical behavior of FCCC-R and the hybrid column to be fully developed.