Effects of key parameters of hybrid cable-stayed suspension bridge on the fatigue resistance of side hangers in bonding zones

Abstract

Hybrid cable-stayed suspension bridges (HCSBs) have excellent mechanical and spanning capacities. However, their hangers in the bonding zones experience high cyclic stresses, and their fatigue failure jeopardize HCSB safety. This study adopted a HCSB finite element model and applied the influence line method to assess the effects of the following six factors on the stress amplitudes of side hangers: ratio of hanger force to vertical force in the stay cable in the bonding zone, relative stiffness of the main beam in the bonding zone, number of hangers in the bonding zone, arrangement pattern of stay cables and hangers, suspension-to-span ratio, and number of auxiliary piers. The exemplary HCSB had asymmetric span arrangement and a main span of 1400 m. Nodal loads were imposed on the main beam in the entire bridge to obtain the influence lines of each hanger and identify the most unfavorable hanger. The values of the above six parameters of the model varied to obtain the new influence lines of each hanger and identify the most unfavorable hanger in the new reasonably completed state. The stress amplitudes of the hangers thus obtained ware compared with those in the original model, reflecting the effects of these six factors on the stress amplitudes in the most unfavorable hanger. Based on the above, the cyclic stress amplitudes of the side hangers were reduced by installing additional stay cables with optimization of their arrangement pattern and relative cross-sectional areas. The results are considered instrumental in improving the fatigue resistance of HCSBs hangers under realistic bridge engineering scenarios.