عنوان مقاله [English]
In this research, punching shear behavior of flat slabs strengthened with ECC concrete has been investigated. In addition, the effect of magnetic water in the mixture of ECC concrete has been studied. In the experimental part of the study, nine reinforced concrete slab specimens with the dimensions of 1000×1000 mm with the same reinforcement ratio were constructed and tested. The reinforcement ratio of the slabs was 0.84%. The slab thickness varied in different specimens. One specimen with 100 mm thickness was made of plane concrete. Six specimens were made by the combination of plane concrete and ECC concrete layers with various thicknesses of 100 and 130 mm. Two of the specimens were made by ECC concrete with 100 mm thickness. The mixture of plane concrete included ordinary portland cement with a water-cement matrix ratio of 0.49. This ratio was 0.5 for ECC Concrete. In some of the specimens, U-shaped shear studs were used for a better connection between ECC concrete and plane concrete layers. ECC concrete has been used in the tension side of the slabs. Punching shear strength and the displacement of each specimen were measured by a Linear Variable Displacement Transducer (LVDT). During the punching shear tests, the load and the maximum deflection were recorded by a data acquisition system, as a result the load-displacement curves were drawn. The tests were conducted using a testing machine so that the load is applied at an average rate of 10 kg/sec. A hydraulic jack was fixed to the frame and used to apply the concentric load on the column stub. The hydraulic jack has a maximum capacity of 1500 kN. Results of the tests have indicated that ECC concrete enhanced the punching shear strength of slabs. The magnetic water improved the ECC concrete flow and load carrying capacity of the slabs. U-shaped shear studs increased the load carrying capacity of the specimens.