Conceptual Design and Execution Methods

This chapter presents a synthesis of multiple aspects of bridge concept design. It describes execution methods and their influence on the concept design. The chapter discusses options for the longitudinal and transverse structural systems for the bridge structure, as well as the choice of structural materials and options for superstructure and substructure. The relationship between the height of the piers and the span lengths is a key parameter for bridge options. Taking into consideration the symmetry of the valley, it is preferable to adopt span lengths decreasing from the centre of the valley towards to the abutments. To illustrate the influence of the construction method on the design of a bridge structure, two examples are considered: a concrete bridge built by the balanced cantilever method; and a composite bridge with the slab deck cast in place on the previously erected steel girders.