大跨度钢箱梁斜拉桥索梁锚固区传力机理

结合南京长江二桥、安庆长江大桥、苏通长江大桥索梁锚固区足尺模型疲劳试验及有限元分析,研究索梁锚固区的传力机理及应力分布。研究表明,由斜拉索传来的巨大压力,通过锚箱底板、承压板与腹板的连接焊缝,以剪力的形式传递到钢箱梁腹板上;锚箱与主梁腹板焊缝处的应力从上到下逐渐增大,在下端达到最大值,承压板上的应力稍小,均满足强度要求;经200万次和400万次(苏通大桥)疲劳加载,均未发现有裂纹发生,应力均无大的变化。验证了设计的正确性和制造工艺的可行性。

Load Transmitting Mechanism of Long-span Steel Box Girder Cable-stayed Bridge on Anchorage Zone between Cable and Beam

With reference to the fatigue tests and finite element analyses of full-scale models of cable-girder anchorage zones of long-span steel box girder cable-stayed bridges like the 2nd Nanjing Yangtze River Bridge, Anqing Yangtze River Bridge and Sutong Yangtze River Bridge, this paper conducts a study on loading mechanism, load transmitting and stress distribution at cable-girder anchorage zones. It comes to the conclusions that the tremendous compressive stress coming from the stay cables transmits to webs of the steel box girders in form of shear force via welding seams jointing bottom plates, bearing plates and webs of anchor housings. The stress at welding seams of the webs of the anchor housings and of the box girders gradually increases in a way from top down to bottom, and reaches the greatest value at the bottom. The stress in the bearing plates is relatively little, but it satisfies the required strength. At fatigue loading of 2 million and 4 million cycles (for Sutong Bridge), cracking does not occur and stress does not vary greatly, which verifies that the design of the anchorage zones is correct and the fabrication procedures are feasible.