Implementation of a beam element including shear-lag in the analysis of bridges with complex static scheme

Abstract This paper deals with the implementation of a beam finite element, suitable for the analysis of steel-concrete composite decks affected by the shear-lag in the slab, in a program for the analysis of bridges with complex static scheme, such as arch bridges, bow-string bridges and cable stayed bridges. The deck model and the relevant beam finite element are adapted in the three-dimensional space on the basis of a model previously proposed by the authors. The problems of the spatial orientation of the element and the connectivity with traditional beam and truss finite elements are discussed. A special constraint is introduced to solve the ill-conditioned problem due to the zero torsional stiffness and the zero flexural stiffness on the co-ordinate plane parallel to the slab. Finally, an application to a realistic arch-latticed bridge is presented in order to show the potentiality of the method.