General Methodology to Non-Destructively Evaluate Bridge Structural Safety

摘要

The objective of this report is to develop a practical methodology tocontinuously monitor the safety of complex structures. The methodology of interest here is a level IV Nondestructive Damage Evaluation (NDE) method which can nondestructively assess the condition of the existing structure and simultaneously evaluate the safety of that same structure utilizing structural reliability concepts. The methodology proposed in this study deals with two broad activities: (1) periodic nondestructive damage detection: and (2) assessment of structural safety based on the results of damage detection. To meet the objective, an established methodology which yields information on the stiffness properties from changes in dynamic properties (i.e., mode shapes and frequencies) of the pre-damaged and post-damaged structures is reviewed. Next, an efficient technique, to directly assess the reliability of a complex structural system (such as a bridge) from the reliabilities of components of the structure, is developed. This technique is numerically validated via several examples using current techniques in structural reliability theory. The efficacy of the combination of these two activities (i.e., the nondestructive damage detection and the structural reliability evaluation) is demonstrated using the following data: (1) modal data obtained from numerical simulations of the dynamic responses of selected structures, and (2) modal data obtained from real structures.