Study On Seismic Behavior Of The Column With Fiber-reinforced Concrete In Column End Region

Reinforced concrete frame column as the primary load-bearing components of tall buildings, should be taken effective way to avoid shear failure. Fiber reinforced concrete (FRC) is a high toughness concrete, which has high tensile toughness and show multiple micro-cracking behaviors and strain hardening properties in direct tension loads, and good control of crack width ability with the increase of deformation that can be used to the shear-critical members, as well as the flexural members subjected to high shear stress reversals. But the cost of FRC is higher than that of ordinary concrete, it is not reality that FRC is used in the entire column, so FRC is used in the plastic hinge region of the column, which can improve the seismic performance of the column and control the cost. Furthermore, more than50%of the cement can be replaced by the industrial waste fly ash when FRC is prepared. Therefore, the study on seismic behavior of reinforced concrete column with FRC in column end region has important significance for improving the seismic performance of reinforced concrete structures, disaster prevention and reduction, reducing environmental pollution and protecting the ecological environment.In this study, nine columns using FRC in column end region and one reinforced concrete column specimens for comparison were designed and quasi-static test was all carried out, the influence of shear span ratio and axial load ratio on hysteretic behavior, deformation capacity, energy dissipation capacity and stiffness degradation rule of columns were investigated and then the seismic performance was evaluated. The crack and failure process of specimens were simulated by the nonlinear analysis software OpenSees, then parametric analysis is conducted for this FRC column, and the influence of shear span ratio, axial load ratio, FRC strength and stirrup ratio of the volume on the seismic behavior were studied. The test results showed that the calculated hysterics curves are similar experimental hysterics curves, and the FRC column with shear span ratio of2is still flexural failure, the strength and stiffness degraded at a lower rate, as well as the FRC column has better deformation capacity, energy dissipation capacity and damage tolerance compared with normal concrete column. Axial load ratio and shear span ratio had a significant effect on ultimate strength, deformation capacity and energy dissipation capacity of FRC column. The FRC column with only shear resisting stirrups satisfied the deformation and energy dissipated requirements. The tension capacity of FRC was considered when the calculation method of bending bearing capacity was established, and shear capacity calculation formula was deduced through theoretical analysis, the calculated value was in good agreement with the experimental value.