According to a recent evaluation, our nation's infrastructure has increasingly presenting signs of deterioration with some elements exhibiting significant deficiencies in conditions and functionality. Regarding the transportation network condition, from the over than 600,000 bridges which are included in the National Bridge Inventory, 46,154 of them are characterized as structurally deficient with the backlog of bridge rehabilitation needs estimated at US$125 billion. Among the many aspects of structural deficiency, corrosion is considered a common cause, both for reinforced concrete and steel bridge deterioration. For steel bridges, corrosion has historically triggered bridge failures resulting to fatalities and injuries. To prevent similar incidents and to ensure public safety, authorities have established provisions dictating the mandatory inspection of bridges for deficiencies identification and maintenance. For girder bridges, supports constitute typical locations of corrosion induced damage due to water and occasionally deicing mixtures presence from the leaking bridge expansion joints. Depending on the severity of thickness loss, the load bearing capacity might be significantly reduced. To address poor residual strength estimations both for rolled un-stiffened as well as plate girders, this dissertation develops tools towards a comprehensive inspection and assessment protocol. For remaining thickness quantification, 3D laser scanning is examined to tackle the shortcoming of conventional data acquisition techniques. The obtained point cloud data are post-processed to provide two-dimensional representations of the remaining section that can be integrated in inspection reports. The derived thickness contour maps can be employed both computationally and analytically for bearing capacity evaluation. Computationally, a methodology is developed to include the derived contour maps in finite element models. Analytically, simplified closed form equations are provided to describe the relation between thickness losses, beam geometry and the remaining bearing capacity. New findings are presented through a multi-step procedure including full scale experimental tests of field corroded girders, finite element modeling and sensitivity analyses to delve into the parameters that significantly affect the capacity of girders with end damage. Finally, analytical tools are developed based on the output of numerous simulated scenarios. The developed procedures are validated both experimentally and computationally providing overall improved estimations compared with the current policies.