The purpose of this study is to improve convergence speed of topology optimization procedure using the existing ESO method and to deal with topology decision of the truss structures according to a boundary condition, such as cantilever type. At the existing ESO topology optimization procedure for the truss structures, the adjustment of member sizes according to target stress has been executed by increasing or reducing a very small value from each member size. In this case, it takes too much iteration till convergence. Accordingly, it is practically hard to obtain optimum topology for a large scale structures. For that reason, it is necessary to improve convergence speed of ESO method more effectively. During the topology decision procedure, member sizes are adjusted by calculating approximate solution for member sizes corresponding to the target stress at every step, the new member sizes are adjusted by such method are applied in FEA procedure of next step.

The goal of this study is to investigate the effectiveness of the use of multi constructional material in unit module plate of steel grid structure and provide engineers and designers an appropriate view point of multi-material topology optimization when making decision and information in design. The material distribution is implemented with the use of 3 materials in a given plate under prescribed loading and boundary conditions. Topology changes through automatic distribution of multi materials are presented during optimization procedures showing that there could be selective structural design possibility when using multi materials. The cross sections, stiffness and cost of material combination are useful information for engineers and designers in making design decision.