钢绞线热铸锚节点高温下抗拉性能试验研究

针对锌铜合金熔点较低（约460℃±10℃）、高温下热铸锚节点容易失效的问题,对预应力钢绞线热铸锚节点进行了高温抗拉性能试验,获得了高温下试件的破坏模式和抗拉承载力,提出了钢绞线热铸锚节点在高温下极限抗拉承载力计算公式,以及在各荷载比下的临界温度,可用于钢绞线热铸锚节点的抗火承载力验算与防火保护层厚度设计. 试验研究表明,温度低于200?℃时,破坏模式为钢绞线断裂;温度高于200?℃时,破坏模式通常为钢绞线滑脱. 温度为150~440?℃时,钢绞线热铸锚节点的极限抗拉承载力随温度升高而降低,287?℃、340?℃、392?℃和425?℃时的极限承载力分别为常温时的77.3%、39%、35.2%和10.5%.

Experimental Study on Tensile Behavior of Hot-cast Anchor Socket of Steel Twisted Wire Strands at Elevated Temperatures

Aiming at the problem that hot-casting sockets are easy to fail at elevated temperatures due to the low melt point of Zn-Cu alloy （approximately 460 ℃±10 ℃）, high-temperature tensile tests were carried out on the hot-cast anchor sockets of prestressing twisted wire strands to obtain the failure modes and tensile capacity of specimens at elevated temperatures. The ultimate tensile capacity calculation formulas of the hot-cast anchor sockets of twisted wire strands and critical temperature under various load ratios were proposed, which can be used for the fire resistance capacity verification and fire protection layer thickness design of the hot-cast anchor sockets. Test results show that the failure mode is the rupture of the strand when the temperature is lower than 200 ℃, while the failure mode is the pull-out of the strand from the socket when the temperature is greater than 200 ℃. When the temperature is in 150~440 ℃ range, the load capacity of the anchorage decreases as the temperature increases. The load capacity at the anchorage temperature of 287 ℃, 340 ℃, 392 ℃ and 425 ℃ is 77.3%, 39%, 35.2% and 10.5% of that at ambient temperature, respectively.