The cost optimisation is important in structural design. The welding times of various welding ng. technologies are different. Using the COSTCOMP program we can calculate the welding times. Adding other times, like flattening plates, surface preparation, cutting, electrode changing, deslagging, painting, etc, we can form a complete cost function. Times are usually general, but costs are different in various countries. Introducing the fabrication and material specific cost ratio of k(f)/k(m), which varies between 0 and 2 kg/min, it is possible to build the cost function from the times and to work out optimisation in different economic conditions. The investigated structures are predominantly welded from plates. Examples are shown of applications for the design of welded box beams and stiffened plates. The fabrication cost percentages for welded box beam and stiffened plate are 29-35 and 46-71% of the total costs, respectively, thus they can have a significant effect on optimum dimensions. The discrete optima depend on the manufacturers, on the k(f)/k(m) ratio and the welding technologies. (C) 1999 Elsevier Science Ltd. All rights reserved.
