Level 2 safety evaluation of concrete-filled steel tubular arch bridges incorporating structural health monitoring and inspection information based on China bridge standards

摘要

Concrete-filled steel tubular (CFST) arch bridges have been widely used in mainland China, and their systematic safety evaluation has gained increasing attention from the bridge authorities in recent years. This paper presents the framework and application of Level 2 safety evaluation of CFST arch bridges, incorporating structural health monitoring (SHM) and inspection information. In contrast with the traditional inspection-based qualitative assessment and direct measurement-based quantitative assessment for SHM, Level 2 safety evaluation considers the inevitable resistance deterioration and site-specific loading under normal operation conditions. For such safety evaluations, the most important element is using the well-established finite element modelling for representing the actual conditions as accurately as possible. Thus, in this study, component and global finite element model (FEM) updating techniques are employed to ensure the local and global behaviour of the updated FEM, through which several types of common CFST arch bridge defects are investigated and updated. Measured site-specific live loads experienced by CFST arch bridges are considered and transformed into design loads for comparison. Unfavourable load patterns are applied to the updated FEM for structural reanalysis, to evaluate the component safety status, and gradually increasing unfavourable load patterns are applied to the FEM to perform an ultimate load-bearing analysis to obtain the global safety reservation. Level 2 safety evaluation is conducted by considering modal parameters, displacements, fatigue damage, and component and global safety status. Level 2 safety evaluation is applied to a typical CFST arch bridge, to demonstrate the entire evaluation process and the effectiveness of the proposed safety evaluation framework.