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Structural Engineering and Mechanics Volume 87, Number 3, August10 2023 , pages 255-272 DOI: https://doi.org/10.12989/sem.2023.87.3.255 |
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Analytical study on cable shape and its lateral and vertical sags for earth-anchored suspension bridges with spatial cables |
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Gen-min Tian, Wen-ming Zhang, Jia-qi Chang and Zhao Liu
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| Abstract | ||
| Spatial cable systems can provide more transverse stiffness and torsional stiffness without sacrificing the vertical bearing capacity compared with conventional vertical cable systems, which is quite lucrative for long-span earth-anchored suspension bridges' development. Higher economy highlights the importance of refined form-finding analysis. Meanwhile, the internal connection between the lateral and vertical sags has not yet been specified. Given this, an analytic algorithm of formfinding for the earth-anchored suspension bridge with spatial cables is proposed in this paper. Through the geometric compatibility condition and mechanical equilibrium condition, the expressions for cable segment, the recurrence relationship between catenary parameters and control equations of spatial cable are established. Additionally, the nonlinear general reduced gradient method is introduced into fast and high-precision numerical analysis. Furthermore, the analytic expression of the lateral and vertical sags is deduced and discussed. This is very significant for the space design above the bridge deck and the optimization of the sag-to-span ratio in the preliminary design stage of the bridge. Finally, the proposed method is verified with the aid of two examples, one being an operational self-anchored suspension bridge (with spatial cables and a 260 m main span), and the other being an earth-anchored suspension bridge under design (with spatial cables and a 500 m main span). The necessity of an iterative calculation for hanger tensions on earth-anchored suspension bridges is confirmed. It is further concluded that the main cable and their connected hangers are in very close inclined planes. | ||
| Key Words | ||
| earth-anchored suspension bridge; hanger force iteration; lateral sag; vertical sag; multi-segment catenary; spatial cables | ||
| Address | ||
| Gen-min Tian, Wen-ming Zhang, Jia-qi Chang and Zhao Liu: Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast University, Nanjing, China | ||