Cyclic loading test for reinforced concrete columns strengthened with high-strength engineered cementitious composite jacket

Abstract

This paper intends to investigate the enhancing effect of high-strength engineered cementitious composite (HS-ECC) jacket on the seismic performance of reinforced concrete (RC) column subjected to cyclic loading. Totally eighteen column specimens were prepared, including conventional RC columns, high-performance mortar (HPM), high-strength fiber-reinforced concrete (HSFRC), and HS-ECC jacketed columns. The effect of different strengthening materials, axial compression ratio (0.2, 0.3, and 0.4), scheme of HS-ECC jacket (strengthening height, cast-in-place or prefabricate), and stirrup spacing on the hysteresis characteristics of the RC columns were explored. Three typical failure modes can be observed depending on different strengthening materials, including shear failure mode, flexural failure mode, and multiple cracking mode. The test results indicate that fiber-reinforced concrete jacketed columns exhibited both high bearing capacity and superior ductility under different axial compression ratios. In particular, HS-ECC jacketed full-column possesses the best overall performance. Under the axial compression ratio of 0.2, the ductility value and the accumulated energy absorption of the HS-ECC jacketed column were improved by 67.7% and 394.8%, respectively, compared with ith conventional RC column. The superior ductility and saturated cracking behavior of HS-ECC ensure jacketed columns have higher damage tolerance and crack closure ability. Compared with HPM and HSFRC jacketed columns, the ultimate displacement of HS-ECC jacketed column was improved by 113.4% and 26.5%, respectively. The accumulated energy dissipation was 866.6% and 111.7% higher than that of HPM and HSFRC jacketed columns. Additionally, the increase in strengthening height could significantly enhance the seismic performance of HS-ECC jacketed columns. In terms of the strengthening scheme, the deformation capacity of cast-in-place HS-ECC jacketed column was better than that of column strengthened by prefabricate HS-ECC slab.