Quantifying Damage Measures for a Composite Steel Girder Bridge using Finite Element Analysis

The purpose of bridge monitoring efforts in Connecticut is to monitor critical vulnerabilities in bridges. In doing so it is important to quantify anticipated changes in measurements resulting from different types and levels of damage with the intent of comparing these changes to the inherent variability in actual bridge measurements to identify the minimum level of vulnerability that can be identified through bridge monitoring. In this paper, three damage measures including, natural frequency, strain distribution, and neutral axis location, will be analyzed using a finite element model of a multi-girder composite steel girder bridge. The bridge examined here has been monitored by the University of Connecticut in conjunction with the Connecticut Department of Transportation for the past several years. Three different types of damage at various levels of severity were examined using an analytical model of the bridge. It was observed that cracking damage and deck deterioration is very difficult to detect showing very little change in any of the damage measures. Only noncomposite action of a girder appears to be consistently detectable showing significant changes in all four damage measures.