Central Load-Bearing Control in the Construction Process of the Concrete Spherical Joint Nandu River Swing Bridge: A Case Study

The rotating mechanism is a significant procedure in swing bridges. In this paper, the Nandu River swing bridge is taken as an engineering case study to exhibit the critical technology of the monitoring process and the construction method of the swing bridge. The research focuses on the central load-bearing control system used to guarantee the security of the construction process. The mechanical problems during the construction process are discussed. Simultaneously, the cable tension and gravity center test are introduced. The non-Hertz contact theory is utilized to calculate the stress distribution of the spherical joint. Furthermore, the overturning moment is computed to monitor the stability of the rotating system based on the stress distribution calculation of the spherical joint. The monitoring process of central load-bearing control is entirely exhibited and discussed. Concurrently, the calculating result of the real-time overturning moment reflects the stability of the rotating construction process, and adjustments are made to ensure the safety of construction. The results show that, during the cable tension process, the middle position of the main arch exhibited 162.3 mm maximum vertical displacement. Meanwhile, the fraction moment was greatly larger than the unbalanced moment. Furthermore, the maximum overturning moment value was 2094.38 kN·m, which was smaller than the resistance of the overturning moment. The present research demonstrates that the non-Hertz contact theory fits the calculation of spherical joint stress distribution. Simultaneously, the middle position of the main arch should be monitored to control the vertical displacement at the cable tensioning stages. The gravity center test and stability control of the rotating construction are the key steps to reaching central load-bearing control.

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