Behavior and strengths of single cast-in anchors in Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC) subjected to a monotonic tension or shear

摘要

Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC) exhibits improved compressive and tensile strengths and strain capacity far superior to those of conventional concrete. The anchors used in UHPFRC are expected to have much higher strengths in concrete-related failure modes and to show a very reliable performance. A total of thirty-three tests, seventeen tension tests and sixteen shear tests, were conducted on anchors in UHPFRC of a 199 MPa compressive strength. The load capacities and displacement capacities of these anchors in UHPFRC were significantly improved compared with the anchors in normal concrete, in both tension and shear. The average ratios of the measured strengths to the predictions by the Concrete Capacity Design (CCD) method were 1.40 for the breakout strength in tension, 1.07 for the breakout strength in shear, and 2.62 for the pryout strength. The enhanced capacities can be attributed to the improved strain capacity and tensile strength of UHPFRC: the improved tensile strength enlarged the projected concrete failure area as well as enhanced the resisting strength and the improved strain capacity secured a reliable performance with low variance, i.e., a higher safety factor than a factor for normal concrete. Three design equations, i.e. breakout strength in tension, breakout strength in shear, and pryout strength, for anchors in UHPFRC were proposed by modifying design equations of ACI 318-11 through regression analyses of the tests, and using the 5% fractile coefficient, they have the same reliability as the design equations of ACI 318-11.