Analytical formulas of thermal deformation of suspension bridges

Deformation of a long-span suspension bridge is mainly caused by ambient temperature changes. The temperature-induced deformation of a bridge is usually calculated using complex three-dimensional finite element analysis, the mechanism of which is often unclear. In this study, we derive general, succinct analytical formulas of the thermal deformation of three-span suspension bridges. The deformation of different components is unified into a one-dimensional thermal expansion formula (?L = LE???T) by introducing an equivalent length LE. The sag effect of side-span cables is characterized by the modification coefficients, which demonstrate that the neglect of the sag effect overestimates the thermal deformation. Furthermore, the thermal deformation of the main- and side-span cables and towers is found to interact with each other as a result of the cable tension changes with varying temperature. The analytical formulas are validated using eight long-span suspension bridges including the Akashi Kaikyo bridge, the longest main-span suspension bridge in the world. The closed-form solutions herein also apply to the self-anchored suspension bridges.

Automated summary

This study derives general and succinct analytical formulas for the thermal deformation of three-span suspension bridges, unifying the deformation of different components through introducing equivalent length and modification coefficients. It is found that the thermal deformation of main- and side-span cables and towers interact with each other, and neglecting the sag effect of side-span cables results in overestimating the thermal deformation.