The Optimization Of A Truss Facade

This paper presents the study of a facade. One of the aims of the designing team is the minimisation of the weight of the facade. Due to architectural constraints, the geometry of the facade is fixed to a highly statically indeterminate truss. Therefore, the minimisation of the weight of the facade is limited to a section optimisation. The objective function is the indicator of volume. Since the number of members is of the order of 1000, exhaustive search methods are impractical. We used a simple iterative process to find optimal sections. In the first iteration all sections are equal. This allows the forces to flow through the facade as if the facade has a constant stiffness. In the next iterations sections are adapted to the forces that arise from the previous iteration. This method quickly converges to an optimal section layout. The results of this method are corroborated by a genetic algorithm. We find that the truss facade with optimal sections consumes less material than an arch with push rods, that transfer the forces to the arch. Furthermore, the influence of buckling can be ignored.