Experimental Study of Thermal Effects on a Long-Span Suspension Bridge

Thermal performance analysis of long-span bridges is important for structural design and safety evaluation; however, its experimental investigation using measured field test data is still insufficient. In this article, 1-year monitoring data of a long-span suspension bridge have been processed to study the thermal effects on structural performance under operating conditions. First, long-term temperature and structural response data, including strain, displacements, and suspender frequency/force, were analyzed statistically for evaluating their correlations. Temperature distribution along the main girder in the longitudinal direction and the temperature gradient in the vertical direction were also analyzed. Statistical analysis results show that the temperature distribution along the girder in the longitudinal direction is nonuniform. The strain change of the lower deck is greater than that of the upper deck in a day. Second, a theoretical study regarding the thermal performance analysis was conducted to calculate structural vertical/longitudinal displacements and thermal-induced internal forces by using measured strains. The estimated displacements are comparable with those measured directly from displacement transducers installed on expansion joints and the global positioning system (GPS) installed on four sections of the girder under normal operating conditions.