The aim of this work was to optimize the choice of the girder height of two-span beam
bridges in order to find more economical forms. Consequently in cooperation with the
engineering company BPR Dr. Schäpertöns Consult and the Chair of Structural Analysis of the
TU Munich a Finite Element Program was expanded by the option to optimize dimensions of
structures. The aim of the optimization was not the minimization of strains but the
minimization of reinforcement and thereby the minimization of costs. The optimization tool
is an excel program based on VBA, that is designed in a way that a user can use it without
even knowing or understanding the code. The user can decide if he wants to do a free-form
optimization or a parametric one. For the parametric optimization one can choose either
linear, quadratic or cubic haunches. The variables during the optimization are the
elementwise cross section heights of the bridge, all other sizes are fixed. The results show
that the optimal girder height corresponds directly to the bending moment. The best results
were achieved for the free-form optimization. When comparing the parametric formulations
one can conclude that the cubic and the linear parametrization can describe the distribution
of the bending moment in the best way. In chapter 6.4.8 statements about the optimization
results for the building practices were determined.
«