Experimental Research On Seismic Behavior Of Concrete-filled RPC Tube

Considering the material characteristics of RPC and the insufficient of current confined concrete, an innovative composite structure, named Concrete-filled RPC tube(CFRT), was presented in this thesis. In this system, high-strength stirrups are arranged in prefabricated reactive powder concrete(RPC) tube and then concrete is cast in RPC tube. In order to explore the composite action of CFRT under axial load and the seismic behavior of CFRT, total 15 large-scale columns were conducted axial compression test and total 6 large-scale columns were conducted cyclic lateral force test.21 CFRT specimens, 3 high-strength stirrup confined concrete(HSCC) specimens and 3 hollow RPC tubes were conducted axial compression test. Composite action between RPC tube and internal concrete, pipe thickness and spiral stirrup spacing are the main factors in tests. The results show that RPC tube of CFRT column only occurs slightly cracking without any spalling when axial load approaches its peak value. In terms of axial carrying capacity, CFRT column is higher than the sum of hollow RPC tube and internal concrete and this composite system realizes the superposition effect. The compressive properties of CFRT columns improve as the space of stirrup decreasing. However, the compressvie properties is almost not affected when the pipe thicknees changed. Based on Mander model and corresponding simplifications, contribution ratio of RPC tube for carrying capacity of CFRT columns is quantified and its value increases from 0.21 to 0.25 with stirrup ratio increasing. Introducing the reduction factor ?, a calculation method for carrying capacity of CFRT is proposed.5 CFRT specimens, 1 HSCC specimens were conducted cyclic lateral force test. spiral stirrup spacing in the hollow RPC tube and total stirrup ratio are the main affected factors in tests. The results shows that the failure pattern of CFRT is flexure failure. The RPC tube of CFRT column only occurs slightly cracking without any spalling during the entire experiment, the concret in the plastic hinge region is comparatively integrated. The bearing capacity and peak displacement of CFRT are significantly higher than that of HSCC. Compared with HSCC, the plastic hinge region of CFRT have a better mechanical performance, therefore, CFRT have better seismic behavior. In terms of seismic behavior, the spiral stirrup spacing have a higher effect than the total stirrup ratio. In addition, the seismic performance of CFRT columns improve as the space of stirrup decreasing.When the total stirrup ratio of CFRT reach the minimum stirrup ratio of American concrete code(ACI318-2011), the CFRT can have a good seismic performance.