Bending Stiffness Identification of Continuous Girder Bridges Using Multiple Rotation Influence Lines

Abstract

Bridge bending stiffness, related to bridge material and geometric properties, is considered an important indicator of bridge performance. Accurately identifying bridge bending stiffness is essential for evaluating the condition of the bridge. The bridge influence line (IL), which can reflect the bending stiffness, is widely used for bending stiffness identification. The most frequently employed IL is deflection IL, which is typically extracted from the deflection response of the midspan section. In practice, a fixed reference point below the midspan section is usually unavailable, thus limiting the application of deflection measurements. Furthermore, existing methods primarily focus on simply supported girder bridges, which are not applicable to continuous girder bridges. This paper proposes a method for identifying the bending stiffness of continuous girder bridges by using multiple rotation influence lines (RILs) of the section near the bearing. The rotation responses of the section near the bearing are measured for RIL extraction since the bearing has a platform for sensor fixation and overcomes the limitation of deflection measurements. The distribution functions are introduced for simulating bending stiffness, and their parameters are estimated by an optimization algorithm using multiple RILs. This approach leverages multiple measurement points and is more accurate than the method using a single RIL. The effectiveness of the proposed method for identifying bridge bending stiffness is verified by both numerical simulations and laboratory experiments. A comparison between the identified bending stiffness using multiple RILs and that using a single RIL assesses the applicability of the proposed method.