Analytical study for strength enhancement of rc column by lateral confinement

Abstract

quotBackground: newlineRC columns in structures are provided with longitudinal steel and lateral confining steel. Since, eight decades, researchers have targeted the assessment of influence of confining steel on ductility demand of RC columns subjected to lateral load because of earthquake. However, the influence of confining steel is yet not attended in terms of improved compressive strength. The confining steel provided in RC columns enhances the column strength. This strength enhancement is not accounted for in the various National Code of practice such as IS 456:2000 and BS 8110-1:1997. As a result, the strength of column remains underestimated and certain strength remains unutilized throughout the life of buildings. This has resulted in wasteful use of material and money. newlineGenerally, the RC columns perform beyond the designed capacity in terms of Pu Mu interaction curve in situation of overloading. The experienced stakeholders of building construction fraternity are well aware of the phenomenon without knowing the reason behind and misuse the reserve strength of RC column to their advantage. newline newlineAim: newline newlineThe aim of this study is to confirm empirically the enhanced strength of confined concrete and analytical evaluation of strength of RC column using confined concrete constitutive model. newlineResearch Method: newline newlineThe experimental investigation has been carried out to formulate the stress-strain relationship of unconfined and confined concrete uniaxial strength. The primary variables are percentage of main steel, and the amount of lateral steel, degree of confinement of RC columns. Total 51 standard cylindrical test specimens were cast and tested in the laboratory for limiting strain value of 0.0035 and the stress - strain relationship is validated with the constitutive law provided by Mander et al. and compared with the idealised curve provided in IS 456:2000. The realistic stress-strain relationship would only predict the correct response of the structural elements under the influence of loads.