Optimal design of truss-structures has always been a fast developing
area of research in the field of engineering optimization and
has made significant progress in the last decade. Optimization of
truss-structures can be classified into three main categories: size,
shape, and topology optimization [1]. Assuming a fixed topology
and configuration (the coordinates of the nodes and connectivity
among various members), size optimization uses the crosssectional
area of each member as the design variables. In shape
optimization, the changes in nodal coordinates are kept as design
variables. It is widely recognized that an optimal geometry of a
structure can greatly improve the structural performance. As to
the topology optimization, it is concerned with the number and
connectivity of the members and joints. In general, it is most easily
represented by discrete variables rather than by those used for
continuous size and geometry optimization problems.