Performance of High-Strength Concrete Columns Confined by Medium Strength of Spirals and Hoops

This paper presents on an experimental study of confined high-strength concrete columns tested under axial compression. The main objective of the research is to know the performance of spirals and hoops with medium strength (400 MPa < fy < 600 MPa) in their contribution on the behaviour of confined high-strength concrete columns. The parameters of the study were concrete strengths, confining steel characteristics i.e: type of confinement (spirals and hoops), yield strength, spacing and volumetric ratio. From the experimental results it was found that the strength enhancement and ductility of confined concrete will decrease with if both of concrete strength and spacing of spirals or hoops increase, and the strain in the test also showed that the release of a cover of concrete core occurs prematurely. Other results shows that satisfactory of circular hoops as confinement steel behaved as good as the spiral reinforcement. The spiral reinforcement provision adopted in the Indonesian Concrete Standard 2002 (SNI 03-2847-2002) is quite reliable when applied in the design of confining steel with medium strength of high-strength concrete columns, therefore it is proposed that the upper limit provision of yield strength of confining steel warrant to be modified.