Temperature-Based Structural Identification of Long-Span Bridges

Temperature-based structural identification (TBSI) is a quantitative structural evaluation approach that relies on responses resulting from temperature fluctuations. Through this approach, the transfer function that defines how thermal induced strains give rise to global displacements and restrained member forces can be captured. This input-output relationship is highly sensitive to mechanisms that pose modeling challenges, such as boundary and continuity conditions, and thus is quite valuable within the model updating process. The method follows the traditional structural identification (St-Id) framework with a priori modeling, experimentation, and model calibration steps appropriately modified to allow for the measurement and simulation of temperature-induced responses. TBSI was evaluated through the use of simulations and laboratory experiments and then implemented to identify an arch bridge. In addition, a comparative study was performed with an independent evaluation of the same bridge using ambient vibration structural identification (AVSI). The results indicate that TBSI and AVSI are synergistic providing complementary information related to a diverse range of structural performances. In addition, the results illustrate several TBSI strong points, including (1) the ability to identify both linear and nonlinear behaviors, (2) the ability to efficiently capture response patterns with long periods, and (3) a strong correlation between the captured transfer function and the behavior of boundary and continuity conditions. (C) 2015 American Society of Civil Engineers.