750kV钢管混凝土变电构架相贯节点SCF试验研究

Test Study on Stress Concentration Factors of Y-Joints in 750kV Concrete Filled Tubular Substation Truss Structure

以国内首例750kV钢管混凝土变电构架工程为背景,对3个采用不同加强方式(即瓦形板、套管和腋板加强)和一个作为对比的无加强钢管混凝土Y型节点在平面内弯矩作用下的应力集中系数(SCF)进行了试验研究.结果表明:相比无加强节点,本文采用的3种加强方式均能显著降低节点的SCF值;通过2种外推方法的对比表明,主管的SCF可以采用线性外推法,而支管SCF需采用二次外推法;增大主管轴压比将显著降低节点的SCF值,使SCF值分布更为均匀.将试验SCF结果与现有规范的计算公式对比表明,现有规范计算结果与支管的SCF试验结果吻合较好,而对主管的SCF明显均偏于保守.

The stress concentration factors of concrete-filled tubular Y-joints subject to in-plane bending were studied, based on the engineering background of the first 750 kV concrete filled tubular sub- station in China.Experimental investigation was performed to investigate the hot spot stress distribution a- long the intersection between chord and brace.Three tubular Y-joint specimens with circular concrete-filled chords under different forms of reinforced components,including doubler-plate, sleeved and haunched rein- forced joints, were tested. In addition, a unreinforced joint specimen was tested for comparison.The test re- suits indicate that three different forms of reinforced components effectively reduce the peak stress concen- tration factors of Y-joints, compared with that of the unreinforced joint. The current research points out that the linear extrapolation method can be used for chords, whereas the quadratic extrapolation method can be used for braces. The stress concentration factor values are effectively reduced and more evenly distributed when the axial compression ratio in chord is increased. Furthermore, the stress concentration factors obtained from the test results were compared with the predictions from some well-established exist- ing stress concentration factor equations.Generally, the prediction results are very consistent with the test results of the braces, but very conservative for concrete-filled chords.