Seismic Performance Analysis of UHPC Composite Columns Confined by GFRP Tubes

In order to study the influence of winding angle and axial compression ratio of GFRP fibers on the seismic performance of UHPC composite columns confined by GFRP tubes, six GFRP tube confined UHPC composite columns and one UHPC composite column were designed, and the quasi-static tests of the specimens under quasi-static load and axial force were carried out, and the skeleton curve characteristics of the structure were analyzed. In order to further explore the effects of diameter-thickness ratio, slenderness ratio, circumferential elastic modulus of confined tubes, and tensile strength of concrete on the seismic performance of the composite column, a finite element analysis model of composite column is established, and the energy dissipation capacity of the structure with different design schemes was analyzed. The results showed that GFRP tube was effective in improving the seismic performance of UHPC columns, and the failure mode, peak load and peak displacement of composite columns were improved, and the finite element analysis results were in good agreement with the experimental results, which verified the effectiveness of the analysis model. Through the extended analysis, it was found that the bearing capacity of the specimen increased and the energy dissipation capacity became worse with the decrease of diameter-thickness ratio and the increase of circumferential elastic modulus. With the decrease of slenderness ratio, the bearing capacity of the specimen increased, the ultimate displacement became smaller, and the energy dissipation capacity became worse. The tensile strength of concrete had an effect on the seismic performance of the specimen, but the effect was small. Through regression analysis, a formula of shear capacity of UHPC composite columns confined by GFRP tubes was proposed.