Essential stressing state features of a large-curvature continuous steel box girder bridge model revealed by modeling experimental data

This paper investigates the structural working behavior of a large-curvature continuous steel box-girder bridge model undergoing a full loading process, applying a new numerical shape function (NSF) method and structural stressing state theory. Firstly, the NSF method expands the experimental data of the bridge model. Then, the expanded data are modeled as generalized strain energy density (GSED) to form structural stressing state modes. And the corresponding stressing state characteristic parameters such as GSED sum are constructed to characterize the stressing state modes. Furthermore, the Mann-Kendall (M - K) criterion detects the essential leap feature of the bridge model's stressing state embodied in the GSED sum-F curve. It is verified that the feature complies with the natural law from quantitative change to qualitative change of a system and is the starting point during the bridge model's failure process, which updated the definition of the bridge model's failure load. Finally, structural stressing state submodes of internal forces are proposed using the expanded strain data, which further evidences the stressing state characteristics of the bridge model over its loading process. The research results explore a new way to deeply analyze the working behavior features of structures and to accurately estimate structural failure loads for structural designs.