Evaluation of dynamic deformations of slab-on-girder bridge under moving trucks with corrosion-damaged columns

A simplified hybrid linear/nonlinear dynamic finite element analysis (SHDFEA) based on visual inspection is introduced as part of a proposed semi-quantitative assessment approach of aged bridge columns. The focus is on the evaluation of the dynamic characteristics and behaviour of slab-on-girder bridges under moving trucks when their columns are subjected to severe corrosion damage. The proposed SHDFEA uses nonlinear finite element analysis to evaluate the damaged columns stiffness, mass and damping throughout the step-by-step time history analysis. The efficiency, accuracy and stability of the proposed SHDFEA are verified through different case studies, where very high numerical stability and fast convergence are achieved. The results show that the nonlinear dynamic analysis presents the most general approach to evaluate the effects of any level of corrosion damage in the column for any case of loading, boundary conditions and any progressive change in the column properties. However, linear dynamic analysis is found to be the most economical alternative when the columns are overdesigned. It is found that with severe local corrosion damage in traditionally designed slab-on-girder bridges columns, their static behaviour mostly remains in the elastic range, and the traffic load magnitude remains below their ultimate static capacity. It is also found that the changes in the bridge dynamic performance parameters are marginal when over-designed columns have severe corrosion damage and their safety and stability are critical.