Optimization of 2-D Steel Truss by Grid Search Method Chetan R. Kakadiya M.E. Structural Engineering, BVM College of Engineering, Vallabh Vidyanagar. Atul N. Desai Associate Professor [M. Tech.], Structural Engineering, BVM College of Engineering, Vallabh Vidyanagar Abstract - Optimization of truss structures for finding optimal cross sectional size and configuration of 2-D trusses to achieve minimum weight is carried out by Grid search method. Function evaluation at various grid points by Excel STAAD VBA interface. For geometry variation Truss heights is in outer loop, no of bays is in inner loop. Generates basic information for geometry like node no, node coordinate, member no, member incidence. Create separate input like loading is different for each geometry and common input like member property, support condition, member specification, and steel design command. Excel creates a separate Staad file for and pass particular information related to geometry required for analysis and design. By this procedure probably optimal solution is getting for 18m span with Pratt truss configuration. Key Words – Optimization by Grid search method, Excel STAAD VBA interface, Size and Configuration optimization. I. INTRODUCTION The basic principle of optimization is to find the best possible solution under given circumstances. The term optimal structure is very uncertain. This is because a structure can be optimal in different aspects. These different aspects are called objectives, and may for instance be the weight, cost or stiffness of the structure. [1] The solution of problem depends on various factors like objective function formulation, constraint formulation, method adopted, starting point, step size etc. Basically there are three different ways of truss optimization. (1) Sizing Optimization, (2) Configuration Optimization, (3) Topology Optimization. • Sizing optimization is the simplest form of structural optimization. The shape of the structure is known and the objective is to optimize the structure by adjusting sizes of the components. [1] • As with sizing optimization the topology (number of holes, beams, etc.) of the structure is already known when using shape optimization, the shape optimization will not result in different shape. In shape optimization the design variables can for example nodal coordinates, Member incidences. [2] • The most general form of structural optimization is topology optimization. As with shape and size optimization the purpose is to and the optimum distribution of material. With topology optimization the resulting shape or topology is not known, the number of holes, bodies, etc., are not decided upon. To solve this problem it is discretized by using finite element method and dividing design domain in to discrete element (mesh). [3] Basic approach is utilizing both Sizing optimization and Configuration optimization by Grid Search method. Grid search method is versatile for discrete objective function and to get trend. It is useful when one can evaluate objective function very quickly at various grid points. This can possible in case of truss like generate no. Of geometries in M. S. Excel, pass this geometry information to structural analysis and design software (e.g. STAAD Pro), perform analysis and steel design in the same software, call software design result and calculate material take off, finally interpret the result. II. OPTIMIZATION METHOD Grid search method is setting up suitable grid in design space, evaluate objective function at all grid points and finding the grid point corresponding to lowest function value. [6] For topology variation change the height of truss and no. of bays along the span. So, grid points are various truss topologies as shown in fig 1. In this method perform multiple run for batter solution. Initially go for wide range grid means points are not closely spaced. After first run set finer grid near to the solution which got from previous. ,QWHUQDWLRQDO-RXUQDORI,QQRYDWLRQVLQ(QJLQHHULQJDQG7HFKQRORJ\,-,(7 9RO,VVXH$SULO  ,661ｱ