Torsional behavior of ultra-high performance concrete squared beams

• Published in: Engineering structures 2013-11, Vol.56, p.372-383
• Main Authors: Yang, In-Hwan, Joh, Changbin, Lee, Jung Woo, Kim, Byung-Suk
• Format: Article
• Language: English
• Subjects: Applied sciences; Beams (structural); Building failures (cracks, physical changes, etc.); Building structure; Buildings. Public works; Concrete structure; Concretes; Construction (buildings and works); Crack; Diagonal compressive stresses; Durability. Pathology. Repairing. Maintenance; Exact sciences and technology; Mathematical models; Reinforcement; Shear strength; Steel fiber; Steel fibers; Stresses. Safety; Structural analysis. Stresses; Torsional strength; Ultimate tensile strength; Ultra-high performance concrete (UHPC); Volume fraction
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2013.05.027

•Increasing the volume fraction of steel fibers improves the cracking and ultimate torsional strengths of the UHPC beams.•The ultimate torsional strength of the UHPC beams increases as the stirrup ratio increases.•The addition of longitudinal rebars is effective at improving the post-cracking behavior of the UHPC beams.•Major diagonal cracks are observed at angles measuring 27–53° from the beam axis. This paper presents experimental results on the torsional behavior of ultra-high performance concrete (UHPC) beams. Thirteen beam specimens with 300×300-mm cross section were cast from UHPC with the compressive strengths greater than 150MPa. The experimental parameters were the specimens’ volume fraction of steel fibers, transverse reinforcement ratio, and longitudinal reinforcement ratio. The test results indicated that the beams’ initial cracking and ultimate torsional strength increased as the volume fraction of steel fibers increased. The ultimate torsional strength and torsional stiffness after initial cracking increased as the stirrup ratios increased, and ultimate torsional strength increased as the longitudinal rebar ratios increased. The effect of the quantity of transverse and longitudinal reinforcement on the angle of the diagonal compressive stresses was investigated. The results of this study provided valuable data that could be used in future studies to develop computational models of the torsional behavior of UHPC beams and predict their ultimate strength.