不同荷载条件下预应力钢绞线双压花锚具性能的试验研究

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

在改进预应力钢绞线压花锚具构造研究的基础上,进行了12个双压花锚具的足尺寸试件试验,研究了该种新型锚具分别受到持续荷载、周期荷载以及疲劳荷载作用时的有关性能．首先研究了锚具由于荷载持续作用所产生的变形以及持荷应力水平的影响,并提出变形计算的建议公式,试验表明24 h持荷未造成该种锚具最大承载能力的下降,而且其变形在破坏时总变形量中所占比例较小．周期荷载作用时,荷载循环次数的增加使锚具每个循环的荷载与变形逐渐呈近似线弹性关系;历经50次重复加卸荷后再次承受静力作用时,锚具性能变化很大,而最大承载力和极限变形能力没有降低．试验还表明,双压花锚具达到了国家标准规定的周期荷载性能和疲劳荷载性能的要求．

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.