Abstract

The trend in movable bridge design over the last century has been to select simple forms for bascule, swing, and vertical lift bridges that have a minimum number of moving parts. Recent advances in technology, however, have resulted in a renewed interest in innovative forms. With this renewed interest in mind, this presentation will explore the use of linkages as the main kinematic and structural elements of movable bridges. Linkages, though widely used in machines and in deployable structures, have rarely been employed in movable bridge design. The presentation will first describe a design methodology for linkage-based movable bridges which includes 1) physical shape-finding to arrive at conceptual designs, 2) generating parametric models and kinematic equations, and 3) shape and sizing structural optimization using heuristic algorithms such as simulated annealing. Multi-objective structural optimization for minimum self-weight and minimum force required for operation is utilized to determine a pareto-optimal set of designs that meet the constraints of current American bridge design code and meet compatibility equations for prescribed kinematic behavior. Based on design priorities, this approach allows for the selection of a final solution. This methodology will be demonstrated for three novel forms which meet the design requirements for the Woodrow Wilson Bridge Design Competition (November 1998) site – a crossing between Alexandria, Virginia and Oxon Hill, Maryland, USA . The presentation will conclude with a brief discussion of the on-going research projects of the Kinetic Structures Laboratory at the University of Notre Dame (Notre Dame, Indiana, USA ).