Strength enhancement in concrete confined by spirals

The strength and ductility of the concrete can be enhanced by confinementlt can be achieved in many ways. Using spirals is one of the ways to enhance the strength by confinement The confinement effect in concrete by spirals can be applicable to enhance the load carrying capacity of columns and shear carrying capacity of beams and flat slabs. This effect prevents structures from catastrophic failures during earthquakes. In this research study, experiments were conducted to determine the anchorage depth of the spiral, the shear enhancement in beams due to confinement by spirals and increment in failure load of flat slab panels a when spiral is used as a shear resistor. The actual shear carrying capacity and theoretical shear carrying capacity of the beams were checked using average integration method and discrete method.The experimental results indicated that the shear carrying capacity of the beam was enhanced by 35.7% for 30mm pitch spiral, 26.8% for 45mm pitch spiral and 16.1% for 60mm pitch spiral. The actual shear carrying capacity based on the experimental results matched closer to the value obtained by the average integration method. The failure load of the flat slab panel was increased by 12.3% when spiral was used as shear resistor