APPLICATION OF TENSIONED PULLOUT TESTS TO INVESTIGATE THE EFFECT OF PRESTRESSING WIRE INDENT GEOMETRY ON BOND AND SPLITTING CHARACTERISTICS

摘要

An experimental program was conducted at Kansas State University to study the geometric properties of indented prestressing wires that induce splitting of the surrounding concrete. Tensioned wire pullout specimens using 5.32-mm-diameter prestressing wires were tested to investigate the angles of the indent that caused the specimens to split. Indent patterns were custom machined to various unique geometries on smooth prestressing wire. The custom geometries provided controlled experiments analyzing various geometrical features influence in concrete splitting.rnEach test consisted of a single wire that was bonded 2.5 inches in a rectangular specimen. The wire was tensioned to 75% of its ultimate strength before concrete was cast in a mold around it. The force in the wire was decreased after the concrete had reached strength of 4,500 psi. The force in the wire above and below the specimen was measured along with the amount of slip on each end of the specimen.rnDifferent geometry patterns were shown to cause the specimens to split as the wire moved through the specimen. Controlled variation in the machining of indent geometries allowed for detection as to what geometrical features are prone to cause splitting and which geometrical features increase bonding capability.