مهندسی عمران شریف (Feb 2021)
PUNCHING SHEAR BEHAVIOR OF FLAT SLABS STRENGTHEND WITH ECC CONCRETE
Abstract
The present study investigates the punching shear behavior of flat slabs strengthened by ECC concrete. In addition, it studies the effect of magnetic water in a mixture of ECC concrete. In the experimental part of the study, nine reinforced concrete slab specimens with the dimensions of $1000\times1000$ mm with the same reinforcement ratio were constructed and tested. The reinforcement ratio of the slabs was . The slab thickness varied in different specimens. One specimen with mm thickness was made of plane concrete. Six specimens were made by combining the plane concrete and ECC concrete layers with different thicknesses of and mm. Two of the specimens were made by ECC concrete with mm thickness. The mixture of plane concrete incorporated an ordinary Portland cement with a water-cement matrix ratio of . This ratio was for ECC Concrete. In some specimens, the U-shaped shear studs were used for a better connection between the ECC concrete and plane concrete layers. ECC concrete has been used on the tension side of the slabs. Both punching shear strength and displacement of each specimen were measured by a Linear Variable Displacement Transducer (LVDT). During the punching shear tests, the load and maximum deflection were recorded by a data acquisition system and onsequently, the load-displacement curves were drawn. The tests were conducted using a testing machine to apply the load at an average rate of kg/sec. A hydraulic jack was fixed to the frame and used to apply the concentric load on the column stub. The hydraulic jack had a maximum capacity of kN. The results of the tests indicated that the 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.
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