Strength of Reinforced Concrete Members in Pure Torsion

순수(純粹)비틀림을 받는 철근(鐵筋)콘크리트 부재(部材)의 내력(耐力)

To establish the rational design method, it is very important that predict accurately load-deformation response on reinforced concrete members. Torque-twist curves of reinforced concrete members in pure torsion were proposed recently by Collins and Hsu, etc. But, it is found that torsional strength of reinforced concrete members based on Hsu's theory is underestimated in the over-all load region except the ultimate state. In this paper, an attempt is made to present the higher-precision of torsional strength on arbitrary loading condition. For this purpose, constitutive equations are derived from which an estimate can be made of the torsional behavior of reinforced concrete members under the pure torsion. Tension stiffness of concrete in both the cracked and uncracked state have been considered. A softening effect that reduces the strength of the concrete by the diagonal cracking of concrete have been appropriately deliberated. Particularly, the experiments was done with 14 test beams to investigate the validity of theoretical analysis.

RC 부재(部材)에 대한 정밀도 높은 하중이력곡선(荷重履歷曲線)의 제안은 합리적인 설계법(設計法)의 수립이라는 관점으로 볼 때 매우 중요하다. 순수비틀림을 받는 RC 부재(部材)의 비틀림모멘트와 비틀림각(角) 관계곡선을 최근 제안한 사람은 Collins, Hsu 등이다. 그러나 그의 비틀림 내력평가(耐力評價) 결과는 극한상태를 제외하고는 모든 하중영역(荷重領域)에 있어서 상당히 과소평가되고 있다. 본 연구에서는 구성방정식(構成方程式)에 콘크리트의 인장강성(引張剛性) 및 수정된 콘크리트 softening 계수(係數)를 도입하여 임의의 하중단계에서도 비틀림내력(耐力)의 정밀도를 높이는데 그 목적(目的)을 두었다. 특히 이론해석(理論解析)의 타당성을 검토하고자 14체(體)의 RC 부재(部材)를 제작하여 재하실험(載荷實驗)을 실시하였다.