大跨度拱桥变截面吊杆索力的分析与识别

上海亭枫公路跨平申线航道的三跨30 m+120 m+30 m连续钢桁架拱桥采用变截面吊杆,其施工过程索力的准确识别具有一定的技术难度,需要有效的理论分析结合实际工程经验来解决。利用等截面吊杆索力的计算公式,结合SAP2000变截面吊杆有限元模型的参数分析结果,推导出不同规格的吊杆基准等效长度。根据吊杆基准等效长度和实测频率,采用一端固定、一端铰接的索力计算公式计算索力,并与相应阶段的设计索力进行比较,可以得到主桥吊杆索力基本符合设计要求。

Analysis and Identification on Cable Forces of in Variable Cross-section Suspenders of Long-span Arch Bridge

The three-span (30m+120m+30m) continuous steel truss arch bridge of Shanghai Tingfeng highway crossing the channel of Pingshen line adopts suspenders with varying-section; the accurate identification of cable forces in suspenders during the construction has certain technical difficulties, which needs effective theoretical analysis and practical engineering experience. Based on the cable force calculation formulae for suspenders with constant-section and the parameter analysis results of SAP2000 finite element modelling of suspenders with varying-section, it has put forward the benchmark equivalent length of suspenders with different specifications. According to the benchmark equivalent length and measured frequency of suspenders, the cable forces are calculated by the cable force calculation formula with boundary condition of one end fixed and another end hinged, and compared with the design cable forces at the corresponding stage, it can be concluded that the cable forces in suspenders of main bridge basically meet the design requirements.