考虑系杆断裂的钢管混凝土刚架系杆拱桥动力响应分析

Dynamic response analysis of CFST rigid frame tied arch bridge considering tie rod fracture

摘要:

为方便计算分析系杆断裂后钢管混凝土刚架系杆拱桥动力响应特性,采用动力系数考虑系杆断裂过程的动力效应,建立了一种考虑系杆断裂效应的等效静力计算方法。与系杆断裂模型试验结果对比,验证了考虑系杆断裂的有限元建模方法正确性。开展某钢管混凝土刚架系杆拱桥响应分析,确定不同系杆断裂情况下的动力系数取值。结果表明:系杆应作为刚架系杆拱桥系杆断裂动力分析主要构件,桥墩面内弯矩和墩顶水平位移可作为辅助分析指标。单侧系杆断裂情况下,断索侧墩顶位移较大,非断索侧墩顶位移很小,端横梁产生剪力和扭矩；双侧系杆断裂情况下,断索侧端横梁不产生扭矩,拱肋轴力减小,桥墩面外弯矩变化不明显。根据桥例分析结果,采用考虑系杆断裂动力效应的刚架系杆拱桥等效静力法计算时,建议单侧断索动力系数取1.4,双侧断索动力系数取1.6。

Abstract:

To facilitate the computation and analysis of the dynamic response of concrete-filled steel tubular (CFST) rigid-frame tied-arch bridges after tie rod fracture, a dynamic coefficient is introduced to account for the dynamic effects during the fracture process. An equivalent static calculation method incorporating the effect of tie rod fracture is proposed. The validity of the finite element modeling approach for simulating tie rod fracture was verified through comparisons with experimental results from a physical model test. A response analysis was carried out on a CFST rigid-frame tied-arch bridge to determine dynamic coefficients under various tie rod fracture scenarios. The results demonstrate that the tie rods should be regarded as the primary components in the dynamic analysis of such bridges after fracture. The in-plane bending moment of the piers and the horizontal displacement at the pier top can serve as supplementary indicators. In the case of single-side tie rod fracture, significant displacement occurs at the pier top on the fractured side, while displacement on the non-fractured side is negligible. The end crossbeam is subjected to shear and torsion. In contrast, under double-side fracture conditions, no torsion is generated in the end crossbeam on the fractured side, the axial force in the arch rib decreases, and the out-of-plane bending moment of the pier shows little variation. Based on the analysis, it is recommended to use a dynamic coefficient of 1.4 for single-side fracture and 1.6 for double-side fracture when applying the equivalent static method for assessing CFST rigid-frame tied-arch bridges considering the dynamic effect of tie rod fracture.