Experimental Study on the Behavior of Double-Ball Anchorage of Prestressing Strands under Different Loading Conditions

Based on its improved details, 12 full-sized specimens of a new type of the double-ball anchorage for prestressing strands were tested to investigate its behaviors related to sustained loading, repeated cyclic loading and fatigue, respectively. The deformation of the anchorage due to sustained loading and the influence of stress levels on its behavior were first studied and then, based on the test results, the formula for evaluating such a deformation was proposed. According to the test, the deformation of the anchorage resulted from the 24-hour sustained loading was relatively small and it did not lower its load-carrying capacity. The repeated cyclic loading tests show that, with increasing numbers of the loading cycles, the load-deformation relationship of the specimens became almost linearly-elastic in each loading cycle; after 50 cycles, the static behavior of the anchorage was significantly changed while the maximum capacity and ultimate deformation ability were not decreased. The test results also show that the double-ball anchorage meets the requirements for both the repeated cyclic loading test and the fatigue test specified in the code.