高温下螺栓球节点螺栓连接抗拉性能试验研究

Experimental Study of the Tensile Performance of Bolt-Ball Connections in Bolt Ball Joint at High Temperatures

为研究高温下空间结构螺栓球节点受力性能,更好地预测螺栓球节点在火灾高温下的承载能力,进行了高温下螺栓球节点螺栓连接抗拉性能试验,研究了不同温度对螺栓球节点抗拉极限承载力的影响.结果表明:拧入深度为1.1倍螺栓直径时,节点破坏形式为螺栓拉断破坏;高温下螺栓球节点抗拉极限承载力在400℃前并没有明显降低,500℃时极限承载力已经降低至常温承载力的50%,温度升温至700℃时极限承载力几乎完全丧失;在不同温度下,试件表面现象不同,当温度达到300℃时,螺栓球表面开始变黄,螺栓并未发生改变,随着温度升高,螺栓球表面逐渐呈现黑色,700℃情况下,螺栓球表面完全被烧红,螺栓球表面和螺栓表面螺纹开始逐渐起皮脱落.根据所测得的试验结果,对不同温度下试件极限承载力折减系数进行回归拟合,提出了高温下螺栓球节点螺栓抗拉承载力计算方法.

To study the force performance and predict the load carrying capacity of bolt ball joint in space structures at high temperatures,we investigated the tensile performance of bolted connections in bolt ball joint at high temperatures.The effect of different temperatures on the ultimate tensile bearing capacity of bolt ball joint was studied.The results show that the bolt ball joint was damaged due to pull-off damage when the screwing depth is 1.1 times the bolt diameter.The ultimate tensile load capacity of the bolt ball joint did not decrease significantly at temperatures less than 400℃;however,it halved at 500℃and reduced to minute value at 700℃.At different temperatures,different changes in specimen surface were observed.For example,when the temperature reached 300℃,the surface of the bolt ball turned yellow;however,the surface of bolt did not change significantly.With a further increase in tempera-ture,the surface of the bolt ball gradually turned black.At 700℃,the surface of the bolt ball was completely red,and the surface and threads of the bolt ball gradually peeled off.According to the test results,the regression fitting on the ultimate bearing capacity reduction coefficient at different temperatures was performed,and a calculation method for the tensile bearing capacity of bolt ball joint at high temperatures was proposed.