Study On Seismic Performance Of RC Circular Columns Strengthened With Pre-stressed CFRP Belts

Earthquake damage analysis shows, reinforced concrete bridge piers and the housing bottom short columns in earthquake disaster easily suffered serious shear failure, thus it is urgent to find the effective strengthening method.The active lateral confinement provided by pre-stressed FRP belts can effectively confine the core concrete and inhibit the conduct of diagonal shear cracks, and the failure mechanism of the short column retrofitted by pre-stressed FRP belts might be changed.It is not perfect at studying the seismic-resistance behavior of reinforced concrete columns retrofitted with pre-stressed FRP belts. The current study focused on the rectangular cross-section column, whose axial compression ratio range was smaller, and didn’t propose appropriate hysteretic model and the design code which was still not available at this time. To improve the status, this study consists of four parts:(1) The seismic-resistance behavior of RC columns under low axial compression retrofitted with pre-stressed CFRP belts is specially described in this paper. The results show that strength, displacement and energy dissipating capacity of the retrofitted columns were improved significantly. The active lateral confinement provided by pre-stressed CFRP belts can effectively inhibit the conduct of diagonal shear cracks and the failure mechanism of the short column retrofitted by pre-stressed CFRP belts might change from shear damage to flexure damage with satisfactory ductility.(2) The seismic-resistance behavior of RC columns retrofitted with pre-stressed FRP belts is specially described in this paper. Test results show that strength, displacement and energy dissipating capacity of the retrofitted pre-damaged columns were improved in a certain extent.(3) The seismic behavior of circular RC columns strengthened with pre-stressed CFRP belts under high axial compression is specially described in this paper. Test results show that the strength, ductility and energy dissipating capacity of the columns with high axial load ratio were improved significantly after strengthened with pre-stressed CFRP belts. The best reasonable control tension stress should be between0.25and0.30strength of CFRP belts.(4) By analyzing the effect on the hysteretic characteristics of the columns strengthened with pre-stressed CFRP belts under different conditions, a series of hysteretic rules for columns strengthened is proposed; Using theoretical analysis and statistic regression analysis, the fonnula of calculated flexural capacity is proposed. The trilinear restoring force model of circular RC columns strengthened with lateral pre-stressed CFRP belts which is capable of considering lateral pre-stress level of CFRP belts and axial load ratio is set up. The result of the model shows good agreement with the test result.78diagrams,21charts,59references...