预应力钢结构锚固节点瞬态温度场分析

根据试验数据,建议了热铸锚填料锌铜合金和冷铸锚填料环氧树脂/钢丸混合物的比热容及导热系数计算公式.基于热传导理论和ABAQUS数值传热模拟平台,进行了ISO834标准火灾下锚固节点截面瞬态温度分布的参数分析.结果表明:随着受火时间的延长,热铸锚杯壁截面温度分布非均匀性逐渐显现,锌铜合金填料的升温速率显著低于锚杯壁;冷铸锚杯壁截面温度分布较均匀,包裹钢丝的填料区域较填料其他区域温度分布非均匀性降低.总体上,锚头沿中心轴的温度分布非均匀性显著,且升温明显滞后于环境温度,无防火保护的情况下锚杯内壁界面处的填料将在较短时间内失效.所提出的热铸锚截面瞬态升温理论计算式,为预应力钢结构锚头抗火承载力验算提供了理论依据.

Transient Temperature Distribution in Anchors for Pre tensioned Cable

Corresponding to the test data, calculation formulas of specific heat capacity and thermal conductivity of filling materials such as zinc copper alloy for hot cast anchors and mixture of epoxy resin/steel shot mixture for cold cast anchors were determined. The parameter analysis on the transient temperature distribution at the section of anchors under ISO 834 standard fire was carried out by using both heat conduction theory and ABAQUS software. It indictes that the non uniform temperature distribution on the cross section of the hot cast anchor socket wall becomes more notable as the fire duration increases. The temperature of filling material increases much more slowly than that of the socket wall. The temperature distribution on the cross section of the cold cast anchor socket wall is relatively uniform. The steel wire mounted in the cold cast anchors can decrease the non uniform distribution of temperature in the filling material. In a word, the temperature distribution along the center axis of anchors is notably non uniform and the temperature in anchors is lower than the fire temperature. If the anchors do not make fire protection, the filling material close to the internal surface of the socket wall will lose its bonding strength within a short time. Finally, an analytical method is proposed to determine the transient temperature distribution in hot cast anchors and can be benefit for the evaluation of the fire resistance of the pre tensioned steel structures involving hot cast anchors.