With the continuous construction of 500 m concrete-filled steel-tube (CFST) arch bridges such as the Bosideng Yangtze River Bridge and the Hejiang Changjiang Highway Bridge, the deviation between the dead pressure line and the arch axis produced by extant arch axis optimization methods increases. Therefore, an arch axis optimization method for long-span CFST arch bridges with a truss section must be designed. Following the optimization of the truss arch axis, this study develops the minimum section eccentricity method that aims to optimize the arch axis of long-span CFST arch bridges. To minimize the main tube eccentricity of the truss arch, the bending moment of the main tubes is reduced by applying the main tube eccentricity method iteratively in a finite element model. Afterward, a smooth and reasonable arch axis is fitted by applying a cubic spline interpolation function in MATLAB. The entire optimization procedure is performed using the Bosideng Yangtze River Bridge as an example. Compared with that of optimal arch axis line types (e.g., parabola and catenary) and other traditional arch axes, the bending moment of main tubes optimized by the proposed method is substantially lower and more uniformly distributed along the arch axis span. The mechanical properties of the finished bridge, including its strength, stiffness, and stability, are all improved, thereby verifying the feasibility of using the proposed method to optimize the arch axis of CFST arch bridges with a truss section.
This paper attempts to evaluate the actual carrying capacity and guarantee the operation safety of Qin Bridge, Ningbo, China. Considering the structural features of the bridge, reasonable field load plans were prepared to realize load test safety control of long-span through tied-arch bridges with single bearing surface (SBS-TTABs). The internal force, stress, and deformation control under different working conditions of static load were calculated, and compared with those measured in static load tests. After that, the natural vibration, and damping features of the target bridge under impact and bumping were explored through pulsating test, barrier-free driving test, and bumping test. The results show that the maximum deflection and strain measured on the midspan section and arch rib section were both smaller than theoretical values, the calibration coefficients of deflection and strain fell in 0.60-0.88 and 0.48-0.88, respectively, indicating that the overall rigidity and strength of the bridge meet relevant code. Under the test loads, the maximum relative residual deflection and the maximum relative residual strain at each measuring point were 12.98% and 11.76%, respectively. Both were below the 20% threshold specified in JTG/T J21-2011. It shows that the bridge span has excellent elastic recovery ability. In dynamic load tests, the fundamental frequency measured by driving test agreed with that measured by bumping test, and the vibrations were smaller than the theoretical values. This means the main span has stable vibration features. Overall, the target bridge has sufficient capacity to withstand Urban-A level vehicle load, under normal use conditions, and the bridge structure belongs to the safe state.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.