Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : ultimate torque

Torsional Behavior of Solid and Hollow Core Self Compacting Concrete Beams Reinforced with Steel Fibers

Tareq S. Al-Attar; Sarmad S. Abdul Qader; Hind A. Hussain

Engineering and Technology Journal, 2019, Volume 37, Issue 7A, Pages 248-255
DOI: 10.30684/etj.37.7A.5

Torsion of structural members and the behavior of steel fiber self- compacting reinforced concrete became the area of interest for many researchers nowadays. The experimental program of the present work consists of casting nine reinforced self-compacting concrete beams in three groups. Each group consists of three beams with the dimensions of 200×300×1500 mm. The first beam has a solid cross-section, the second beam has a hollow core with the dimensions of 60×120×1500mm and the last beam has a hollow core with the dimensions of 80×180×1500mm. The steel fiber contents were 0, 0.5 and 1.0 % by volume for first, second and third groups respectively. The torsional angle of twist versus torsional moment (torque) of each beam was found during the experiments, and the effect of variables, fibers volume fraction and section geometry, on this relationship was investigated. Moreover, the fresh and hardened properties of concrete were carried out using several tests, which included slump flow, L-Box, compressive strength, tensile strength, and finally the torsion test. The current results showed that the addition of steel fibers has improved the torsional strength for all beams and the fibers were more effective in hollow core sections than in the solid ones.

Strengthening of Ferrocement Beams in Torsion by CFRP Strips

Aseel Sami Al-Obaidy; Kaiss F.Sarsam; Alaa K. Abdul Karim

Engineering and Technology Journal, 2014, Volume 32, Issue 3, Pages 702-719

Torsion is resisted well by closed form reinforcement, due to the circulatory nature of the torsion inducing shear flow stresses in a beam. Therefore, it will be more efficient to have strengthening schemes, which are wrapped in closed form around the cross section. An experimental work was carried out and used superplasticizer with mix 1:1.5 to improve the mechanical properties of mortar. 12 rectangular beams (50x120)mm and 1m length are cast, strengthened and tested under pure torsion. The Variables considered in the test program include: effect number of wire mesh layers ( unit ), this unit consists of two layers of wire mesh with skeletal steel, (2, 3, 4) units and effect spacing of CFRP strips, (100,160,200) mm c/c. Test results are discussed based on torque – rotation behavior and influence of parameters on ultimate torque and failure modes. Generally, using optimum dosage of super plasticizer (1.4 % of weight of cement) gave compressive strength 65.65 MPa. Increasing the number of units from 2 to 4(reinforcement near the surface of beam section) led to increased ultimate torque by (13.44 %) and from 2 to 3(uniformly distributed reinforcement) led to increases the ultimate torque by only (3.24 %). When the beams are strengthened with CFRP strips, the lowest and highest increase in torque is at 112 % (4-units,@200 spacing) and 312 % (4-units,@100 spacing), respectively. The ultimate torque of beams with CFRP strips @ 100 mm and 160 mm spacing is greater than beams with CFRP strips @ 200 mm spacing by ( 94.34,45.28) %, respectively for the group having 4-units.