The unit load method-some recent applications

Abstract

The Unit Load Method is originally proposed as a procedure to optimize the tensioning process for the stay-cables in cable-stayed bridges and is implemented in a well-established bridge-design software package for this purpose. The implementation of this method takes into account all relevant effects for the design of cable stayed bridges including construction sequence, second order theory, large displacements, cable sag, and time-dependent effects, such as creep and shrinkage or cable relaxation. The underlying ideas of this method can also be applied to other optimization problems in structural engineering. This chapter gives an overview about the wide range of possible applications for which this method can be used, and it finishes with examples from practical experiences with the Unit Load Method. The Unit Load Method has been developed to achieve a pre-defined target configuration of section forces in cable-stayed bridges by optimizing the tensioning of the stay-cables. Recently, the method is developed further into a versatile design tool that allows the definition of a target distribution of section forces or deflections in any structure. Using the Unit Load Method, the necessary adjustments in a pre-determined set of constrains is computed to achieve exactly this distribution. The chapter briefly describes the method and gives three application examples where this method is used: a cable-stayed bridge, a concrete arch, and the application of this method to the automated simulation of the incremental launching process of bridges.