Free vibration analysis of horizontally curved composite concrete-steel I-girder bridges

Curved composite concrete-steel I-girder bridges provide an exceptional solution to the problems of urban congestion, traffic, and pollution, but their behavior is quite complex due to the coupled bending and torsion response of the bridges. Moreover, dynamic behavior of curved bridges further complicates the problem. The majority of curved bridges today are designed using complex analytical methods; therefore, a strong need exists for simplified design methods in the form of empirical equations for the structural design parameters. In this paper, a sensitivity study is conducted to examine the effect of various design parameters on the free-vibration response of curved composite concrete-steel I-girder bridges. In order to determine their fundamental frequency and corresponding mode shapes, an extensive parametric study is conducted on 336 straight and curved bridges. ABAQUS software package was employed to carry out the numerical simulation for the considered bridges in order to obtain the fundamental frequencies. From the results of the parametric study, simple-to-use equations are developed to predict the fundamental frequency of curved composite concrete-steel I-girder bridges. It is shown that the developed equations are equally applicable to curved composite steel I-girder bridges of simple span or multi-spans with equal span lengths.