PERFORMANCE OF HIGH STRENGTH REINFORCED CONCRETE CONTINUOUS BEAMS UNDER PURE TORSION

Torsion rarely occurs by itself only. It is usually combined with otheractions such as flexure and shear. Even-though, the performance of highstrength reinforced concrete continuous beams under pure torsion isinvestigated in this study. Torsional moments were acted at the externalsupports via applying external loads far away from the vertical plane ofbending at various eccentricities from the axis of the RC beams until failure.Variables considered in this study are absolute vertical displacement of theexternal supports, torsional moment’s capacity, and angle of twist and initialcracking stages of loading. Four increments of 10 cm in each of loadingeccentricity started from 30 cm arm of loading were investigated.According to experimental results; when applied load eccentricity increasedfrom 30cm to 60cm, the absolute vertical displacement increased about56.315% and the angle of twist increased about 55.44% at failure while thegenerated twisting moments increased about 25.58% . It has been also foundthat the ultimate failure loading capacity of beams decreased about 37.21%when the load eccentricity increased from 30cm to 60cm. Furthermore, theinitial cracking was monitored; it was found that cracking occurs at higherstages of loading with low loading eccentricity. The initial cracking recordsappeared at 79.07%, 77.78%, 74.3% and 66.67% of loading when loads armwere 30, 40, 50 and 60cm, respectively.

Keywords:

High strength concrete , continuous beam , pure torsion , absolute vertical displacement , angle of twist