Abstract:
Aiming at the poor punching resistance of normal reinforced concrete slab-column connections, based on domestic PE fibers, a high-strength, high-ductility Engineered Cementitious Composite (PE-ECC) was developed. Moreover, a new type of slab-column connections with the concrete replaced by the domestic PE-ECC in the core and in the area of 1-2 times the slab thickness around the columns is proposed. Six new type slab-column connections and normal ones are designed and fabricated for the punching shear test. The experimental results show that the punching shear capacity and ductility of new slab-column connections are effectively improved, compared with those of normal slab-column connections. With the expansion of the ECC replacement range from 1 h to 2 h, the ultimate shear capacity of the new three slab-column connections with the same reinforcement ratio has increased by 31.8%, 49.2%, and 81.5%, respectively. At the same time, the ductility coefficients have also increased by 39.5%, 65.4%, and 83.9%, which verify the practicality. Due to the replacement range of ECC and reinforcement ratios, punching failure occurs along the edge of the column and along the ECC-concrete interface. With the increase in reinforcement ratio, the post-cracking stiffness and ultimate bearing capacity of slab-column connections are significantly improved, but the ductility is reduced, and the failure mode is gradually shifted to punching failure. In addition, four current concrete codes, including the Chinese Code, are used to calculate the punching shear capacity of the new slab-column connections and to compare them with the test results. The research results show that there exist different degrees of deviation between the calculated values and test values. The research group will conduct in-depth research on the reasonable replacement range of PE-ECC and the appropriate calculation formula for shear resistance in subsequent studies.