Ferhat Erdal

Adaptive Harmony Search Method for Structural Optimization

This paper presents an adaptive harmony search algorithm for solving structural optimization problems. The harmony memory considering rate and pitch adjusting rate are conceived as the two main parameters of the technique for generating new solution vectors. In the standard implementation of the technique appropriate constant values are assigned to these parameters following a sensitivity analysis for each problem considered. The success of the optimization process is directly related on a chosen parameter value set. The adaptive harmony search algorithm proposed here incorporates a new approach for adjusting these parameters automatically during the search for the most efficient optimization process. The efficiency of the proposed algorithm is numerically investigated using two large-scale steel frameworks that are designed for minimum weight according to the provisions of ASD-AISC specification. The solutions obtained are compared with those of the standard algorithm as well as of the other metaheuristic search techniques. It is shown that the proposed algorithm improves performance of the technique and it renders unnecessary the initial selection of the harmony search parameters.

Optimum design of grillage systems under code provisions using particle swarm optimization

This paper presents particle swarm optimization based optimum design algorithm for the grillage systems. The optimum design problem is formulated considering the provisions of LRFD-AISC (Load and Resistance Factor Design, American Institute of Steel Construction). The optimum design algorithm selects the appropriate W-sections for the beams of the grillage system such that the design constraints are satisfied and the grillage weight is the minimum. The efficiency of the proposed algorithm is numerically investigated considering a number of grillage design examples.

Optimum Design of Corrugated Web Beams Using Stochastic Search Techniques

In the present research, the designation of corrugated steel web beams is formulated as optimum design problem. The minimum weights of these new generation steel beams are taken as the objective functions while the design constraints are respectively implemented from BS EN19931:2005 (Annex-D, Eurocode 3) ve DIN 18-800 Teil-1. Firefly and hunting search stochastic optimization techniques are used for obtaining the solution of the design problem. The thickness and height of web, distance between the peaks of the following two web curves, the width and thickness of flange will be considered as the problem design variables. The formulation of the design problem considering the limitations of the above mentioned turns out to be a discrete programming problem. Number of design examples considered to demonstrate the efficiency of the algorithms. Keywords—structural optimization, corrugated web beams, stochastic searh methods, firefly algorithm, hunting search.

Structural features of cold-formed steel profiles

Using capacity of cold-formed steel sections increases thanks to the opportunities which are offered by the developing technology. Low production cost and variety of profiles that can be produce easy, fast, high quality provide to improve its popularity as a structural material. In production, Sulphur and Phosphorous accumulation region occurs at intersection region of flanges and web of hot rolled steel profile. This causes to decrease strength of profile. Other difference between cold-formed and hot rolled steel sections is that mechanical properties of steel material homogeneously distributes throughout the profile. Both in frame and truss systems, cold-formed steel profiles develop both as main and secondary bearing element. These present variety options to the designers with pure, galvanized, aluminized applications. As with many building materials, mechanical behavior of cold-formed steel profile is quite complex due to the nature of thin walled steel sections. Design and analysis methods of cold-formed steel profile are rapidly shaped day by day. The general theory of beams investigated in past studies make possible analyses of cold-formed steel profile. Moreover, in structural systems, using of cold-formed steel profile provide height strength besides sustainable, environmentalist, green building because it requires less material and cost. Although these profiles have many advantages, use of cold-formed steel profiles in our country structures is rather limited unfortunately. New steel construction regulations in Turkey also do not mention cold-formed thin walled steel structure. Main purpose of this study reviews structural specifications of cold-formed steel profiles which are applied world-wide. A R T I C L E I N F O