Nonlinear Analysis of Torsion in Reinforced Concrete Members after Developing Initial Crack

Background/Objectives: Nonlinear analysis of torsion in reinforced concrete members after developing initial crack is a significant effect on piece life time. Methods/Statistical Analysis: As a result of integration and cohesion of members in the reinforced concrete structures Torsion typically occurs. Reduced torsional stiffness problem was presented after semi-brittle break out in concrete due to presence of initial cracks in outer surfaces of concrete element in determining torsional stiffness. Findings: The idea was that reduced torsional stiffness is approximately one-tenth of its value before cracking and this is very effective on the distribution of anchors in the structure. After these studies, different torsion theories were presented which measured the reduced stiffness by using different methods. In this paper, by using these theories, a code was written for torsional analysis of reinforced concrete after cracking called "nlarctm" and 23 rectangular cross-sections were controlled and compared by this program. Comparisons of anchor changes was based on the torsion angle and results indicated that cross-section number (18) has higher torsional strength than similar cross-sections. Applications/Improvements: The results of this research shows that by comparing three effects the resistance of reinforcements, compressive strength and the distance of collars, it's concluded that all of them are very effective in increase or decrease.