基于主梁轴力的部分地锚斜拉桥极限跨径及关键部位力学响应

Dynamic Response of Key Parts and Extreme Span Length of Partially Earth-anchored Cable-stayed Bridges Based on Axial Force of the Girder

为了解决部分地锚斜拉桥极限跨径不清晰的问题,以钢主梁极限抗拉、抗压强度相等即跨中地锚段主梁所受拉力和塔根处主梁所受压力相等为前提,基于斜拉桥索膜理论,求解部分地锚斜拉桥极限跨径,并得到极限锚跨比.推导了部分地锚斜拉桥极限跨径下的关键力学响应并与有限元解进行对比.研究结果表明:基于主梁轴力的部分地锚斜拉桥极限跨径约为普通自锚斜拉桥的1.4倍,其极限锚跨比约为0.293;近似计算公式推导的部分地锚斜拉桥关键力学响应与有限元结果基本吻合,误差产生的主要原因是实际桥梁结构中拉索布置体系通常为扇形而非辐射型.公式能满足概念设计阶段的要求,适用于快速分析部分地锚斜拉桥的受力特征与关键响应.

To explore the extreme span length of partially earth-anchored cable-stayed bridges more deeply, on the premise that ultimate tensile and compressive strength are equal for steel girder, that is, tension of steel girder at cross anchor and end of tower are equal, with cable-membrane theory of cable-stayed bridge to solving ultimate span length of partially earth-anchored and ratio of ultimate anchor-span ratio key dynamic responses were derived and the calculated outcomes were compared with solution attained from one finite element model. The results show that the ultimate span length of partially earth-anchored cable-stayed bridges based on axial force of the girder is 1.4 times as that of the conventional cable-stayed bridge, and the ultimate anchor-span ratio is about 0.293. In this paper, the key derived dynamic responses are consistent with that of the finite element model. The error is due to the fact that the cable arrangement system is usually fan-shaped rather than a radiation pattern in the real bridge structure. The presented theoretical equation can meet the requirements of the conceptual design, and it is suitable for analyzing the key dynamic responses and conducting mechanical analysis of partially earth-anchored cable-stayed bridges.