Analytical solution to temperature-induced deformation of suspension bridges

Abstract

Varying ambient temperature may cause significant deformation of long-span suspension bridges. This study investigates the mechanisms of the temperature-induced mid-span deflection and tower-top horizontal displacement of suspension bridges, and formulates the general analytical solutions to the thermal responses of ground-anchored suspension bridges. The temperature-induced mid-span deflection can be determined from the superposition of deflections caused by each of the separate temperature changes of the main-span cable, side-span cables, and towers, while the tower-top horizontal displacement is a combination of the thermal effects of the side-span cables and towers. It is found that the cable temperature plays the dominant role in the mid-span deflection and tower-top horizontal displacement. Moreover, the temperature effective length is proposed and a unified formula of the temperature-induced bridge responses is obtained. The accuracy of the proposed formulas is verified through the field monitoring data of the 2132-m-long Tsing Ma Bridge at Hong Kong. The present study not only provides a simple, general, and unified analytical solution to the temperature-induced deformation of long-span suspension bridges, but also assists engineers in understanding the mechanisms of thermal behaviours of such bridges.