Tayfun Dede

Weight minimization of trusses with genetic algorithm

This study is concerned with encoding types such as value encoding and binary encoding for continuous and discrete optimization with a GA, which is coded in FORTRAN and considers stress and displacement constraints, in view of weight minimization of truss structures. Moreover, when continuous optimization is performed, the challenge of huge search space due to the effort of considering continuous set of design variables is overcame by a mechanism introduced as restricted range approach (RRA) in this study. In comparison with the literature, it is concluded that the program developed in this study can be effectively used in the weight minimization of truss structures. It is also came to the conclusion that value encoding overcomes the adverse effects of Hamming-cliff, and that value encoding requires less computer memory and time, never destroys the fit chromosome.

Combined size and shape optimization of structures with a new meta-heuristic algorithm

TLBO has shown better performance with less computational effort.TLBO can be effectively used for size and shape optimization of structures.TLBO can be easily extended for the optimization of other structural designs. In this study, a new meta-heuristic algorithm called teaching-learning-based optimization (TLBO) is used for the size and shape optimization of structures. The TLBO algorithm is based on the effect of the influence of a teacher on the output of learners in a class. The cross-sectional areas of the bar element and the nodal coordinates of the structural system are the design variables for size and shape optimization, respectively. Displacement, allowable stress and the Euler buckling stress are taken as the constraint for the problem considered. Some truss structures are designed by using this new algorithm to show the efficiency of the TLBO algorithm. The results obtained from this study are compared with those reported in the literature. It is concluded that the TLBO algorithm presented in this study can be effectively used in combined size and shape optimization of the structures.

Materially nonlinear free vibration analysis of reinforced concrete beam

The aim of this paper is to do materially nonlinear free vibration analysis of a beam by using the finite element method. In finite element modeling, two approaches are used. In the first approach, the material matrices of concrete and reinforcement are constructed separately, then superimposed to obtain the element stiffness matrix. In the second approach, the reinforcement is assumed to be uniformly distributed throughout the beam. So, the beam is modeled as a single composite element with increasing the modulus of elasticity of concrete by considering the reinforcement ratio. For these two approaches, elastic-perfectly plastic stress-strain relationship is used in compression. In tension, a stress-strain relationship considering tension softening is used. In order to obtain the stiffness and mass matrices of the beam at initial, yield, and failure, a computer program is coded in MATLAB. After these matrices are obtained, MATLAB is used to obtain the nonlinear frequency parameters and mode shapes. It is concluded that the approaches and the model considered in this study can effectively be used in the materially nonlinear free vibration analysis of reinforced concrete (RC) beams. It is also concluded that the effects of the change in the stiffness matrix from initial to yield on the nonlinear frequency parameters of the beam are always larger than those of the change from yield to failure.

Advanced Optimization Techniques and Their Applications in Civil Engineering

Department of Civil Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey Department of Civil Engineering, Universidade de Passo Fundo, 99001-970 Passo Fundo, RS, Brazil ICITECH, Department of Construction Engineering, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain Department of Mechanical Engineering, Sardar Vallabhai National Institute of Technology, Gujarat 395007, India