约束浆锚搭接连接高温性能试验研究

为了研究钢筋约束浆锚搭接连接在高温下的性能,采用恒温加载方式,对36个插入式预留孔灌浆钢筋搭接连接试件进行了高温下的单向拉伸试验。钢筋直径分别为12 mm和14 mm,试验温度依次为常温、200、300、400、500、600℃等。分析了试件的破坏形态、荷载-位移曲线及荷载随温度的变化规律。结果表明:常温下,搭接长度取为1. 0倍基本锚固长度的约束浆锚搭接连接试件,钢筋拉断于连接外部,连接性能可靠;随着温度升高,由于材料性能劣化,连接件的承载力逐渐下降;相同温度下,钢筋直径较大时连接件承载力下降幅度越小;从常温至300℃时,钢筋断于试件外部;400~600℃时,钢筋断于试件内部;试件破坏形态均为钢筋拉断,属于延性破坏。

Experimental research on connection performance of restraint grouting-anchoring overlap-joint of steel bar subjected to high temperature

In order to investigate connection performance of restraint grouting-anchoring overlap-joint of steel bar at high temperature, 36 plug-in filling holes for lap joint of steel bar specimens were tested under unidirectional tension after the specimens reached a thermal steady state. The influences of experimental parameters were studied. The parameters included two diameters of bar diameter (12,14mm) and six different testing temperatures ranging from normal temperature to 200, 300, 400, 500℃ and 600℃. Failure modes of specimens, load-displacement curves and the laws of ultimate bearing capacity varying with the temperature were analyzed. The test results indicate that the steel bars break off outside the connection region for the joint whose lap length is 1.0 time of la (la is lapped length of steel bar) at normal temperature, which verifies the reliability of the connection. With the deterioration of material property, the bearing capacity of the specimen decreases with the increasing of temperature. For bigger steel bar diameter, the bearing capacity has less loss at the same temperature. At the temperature range of normal temperature to 300℃, the steel bars break off outside the specimen, while at the temperature range of no less than 400℃, the steel bars break off inside the specimen. No matter at any temperature, the failure mode of specimens is always the tension fracture of steel bar, which belongs to ductile failure.