An approximate method for dynamic analysis of skewed highway bridges with continuous rigid deck

In this paper using a 3DOFs analytical model an approximate hand-method is presented for dynamic analysis of skewed highway bridges with continuous rigid deck. In modeling the structure it is assumed that the deck of the bridge is rigid in-plane. As a result of this assumption the deck moves only on a horizontal plane and the vertical movements are restrained. The translational and rotational stiffness of the substructure and the shear stiffness of the elastomeric bearings on the two abutments are modeled with linear springs. To calculate the natural circular frequencies and internal forces of skewed highway bridges, simplified formulae are presented. The capability and accuracy of the proposed method for seismic analysis are compared with the results of finite element modeling of a practical example. It is generally possible that the deck rigidity assumption underestimates the seismic responses of bridge, but the results show that it sufficiently estimates the natural frequencies and internal forces with a reliable margin of error which is favorable and acceptable for designers in the preliminary stages of design. The approximate method is capable of dynamic analysis of skewed highway bridges with continuous rigid deck in the preliminary stages of the design process. In addition, the preliminary values of this method can help to identify the unknown errors occurring during finite element modeling of the structural model.