Abstract

Aiming at the problems of main cable geometry calculation and control accuracy in construction for long-span asymmetric suspension bridges, this paper proposes a practical method for main cable geometry calculation of asymmetric suspension bridges based on the Rushankou Bridge. Firstly, a hanger–pylon–girder model was established to obtain the constraint force at the hanger top. Then, with the mid-span sag of the main cable set as the control target, the coordinates and unstressed length of the main cable in the completed bridge state were obtained based on the pylon–cable model. Finally, the final main cable geometry and unstressed length were obtained based on the main cable–hanger–pylon–girder model. The reliability of the method in this paper was validated by engineering monitoring data. Using the simulation model, the influence laws and degrees of parameters including temperature, main cable elastic modulus, main cable weight, hanger force and main girder weight on the main cable geometry were investigated. It is indicated that the method in this paper is capable of accurately calculating the main cable shape of asymmetric suspension bridges. After the installation of cable clamps and hangers, the theoretical and measured deformations of the main cable are in good agreement. The theoretical and measured values at the mid-span L/2 of the main span are −233.9 cm and −234.7 cm, respectively, with a deviation of 8 mm. The largest discrepancy between the calculated and actual deformations of the main cable is located at 7L/8 of the main span, which is merely 2.2 cm. The deformation of the main cable is greatly affected by temperature changes; each 1 °C temperature variation leads to a mid-span deformation of about 2.4 cm in the main cable. If the influence of temperature variation on main cable geometry is ignored during construction, it will cause errors in the main cable elevation after installation. The effect of the main cable elastic modulus on its deformation cannot be neglected, and a 10% variation in the main cable elastic modulus leads to a 58 cm change in the main cable geometry.

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