Study on Fatigue Characteristics of FRP Tendons Anchored by HEM and Development of HEM Anchorage Having Large Capacity with FRP Multiple Cables

通过疲劳拉伸试验发现，碳纤维绞线采用折边锚固比采用环氧树脂锚固具有更好的性能。为了阐明上述差异及其在疲劳载荷作用下的作用机理，进行了试验和分析研究。此外，还为“斜拉桥”等大型结构开发了具有大容量的多股CFRP束的卷边索握持器。本研究取得的主要成果如下：1.明确了HEM和环氧树脂锚固机理的区别。在树脂锚固过程中，随着疲劳荷载循环次数的增加，钢套与CFRP钢绞线之间的相对变形幅值增大。结果表明：1.树脂锚固端CFRP筋的相对变形量增大，温升高达80度，将导致CFRP筋的基质树脂疲劳薄弱区。在HEM锚固中，CFRP筋在加载端的温升远小于树脂锚固，因为其相对变形幅度比树脂锚固小得多。由于剪切预应力的引入，降低了荷载幅值，使加有环氧树脂的荷载幅值变小。已研制出2500kN、12股碳纤维筋的大吨位HEM锚具。通过拉伸试验、长期载荷试验和疲劳试验，证实了研制的HEM锚具在工程实践中是可行的。

From fatigue tensile tests, it was found that the characteristics of CFRP strands using HEM anchorage is advantageous than that of epoxy resin anchorage. To clarify the above difference and the mechanism of both anchorages under fatigue loading the experimental and analytical investigations were made. Also, HEM tendon grip having the large capacity with multiple CFRP strands have been developed for large structure such as "Cable Stayed Bridge". Main results obtained in this study are summarized as follows:1. The difference of anchoring mechanism between HEM and epoxy resin anchorage is cleared. In resin anchorage, the relative deformation amplitude between steel sleeve and CFRP strand has increased according to the increment of cycles of fatigue loading. The temperature rise up to 80 degrees due to the increment of relative deformation in CFRP strand at the loaded end of resin anchorage will cause the weak area of matrix resin of CFRP strand for fatigue.2. In HEM anchorage, the rise in temperature of CFRP strand at the loaded end is much smaller than that of resin anchorage, since the relative deformation amplitude is quite small compare to that of resin anchorage.3. The load amplitude for HEM is smaller than that of the one with epoxy resin, because of the reduction of load amplitude affected by the introduction of shear prestress.4. HEM anchorage having large capacity of 2500kN with twelve CFRP strands has been developed. From the tensile tests, long term loading tests and fatigue tests, it was confirmed that developed HEM anchorage can be used in the practice.