超高压变电构架钢管混凝土Y型相贯节点平面内受弯性能研究

In-plane bending behavior of Y-joints in concrete filled tubular truss structures of EHV substation

以国内首例采用钢管混凝土的750 kV超高压变电构架工程为背景,设计了3个1∶2缩尺、主管灌注混凝土的Y型相贯节点试件,其中包括2个采用不同加强方式(即瓦形板、外套筒加强)和1个作为对比的无加强节点试件,并对其进行了平面内受弯性能试验。试验结果表明:相比无加强节点,采用的2种加强节点的最终破坏形态均为支管失效破坏,均符合"强柱弱梁"的设计原则;节点的转动刚度和受弯承载力均显著提高,平面内转动刚度均可达到欧洲规范规定的刚性节点要求,且平面内受弯承载力基本可以达到支管全截面塑性时的弯矩值。此外,对节点的有限元分析表明:主管轴压比、瓦形板长度和宽度对节点刚度和承载力影响较小,而瓦形板厚度对此影响较为显著。

Based on the engineering background of the concrete filled tubular truss structures of 750 kV EHV substation in China, three specimens of 1 ： 2 scaled Y-joints were designed and tested subjected to in-plane bending, which included two circular concrete-filled chords tubular Y-joints specimens with different forms of reinforcement （doubler-plate and sleeve） and a non-reinforced joint specimen for comparison. Test results indicate that the failure patterns of the reinforced joints are the branch pipe failure, which is in accord with the design concept of ＇ strong- column and weak-beam＇. The two joint specimens with different forms of reinforcement can significantly improve the bending stiffness and bending resistance of this joint. The in-plane bending stiffness of the reinforced joints can meet the requirements of the rigid joints of the Eurcode 3, and their in-plane bending resistance can achieve the cross- section plastic resistance of branch pipe. In addition, results of the FE analysis show that thickness of the doubler- plate can make the stiffness and ultimate strength of doubler-plate reinforced joints increase considerably, while the influences of the chord axial compression ratio, length and width of doubler-plate are not significant.