Journal of Engineering and Sustainable Development
This research deals with the thermal and thermo-structural behavior of concrete-steel composite b... more This research deals with the thermal and thermo-structural behavior of concrete-steel composite box-girder bridge under the amalgamation of environmental thermal loads: global solar radiation, ambient air temperature, and wind speed. To achieve this goal, the experimental composite box-girder bridge segment with a full-scale cross-section erected in a campus of Gaziantep University, Turkey; and the series of numerical thermal analyses are conducted. The hourly fluctuations of the numerical temperatures matched well with the experimental ones. This research also submits a theoretical extensive study of the effect of shear connector's number and arrangement at the concrete-steel interface on the hourly vertical thermal movements with an emphasis on the degree of composite interaction. Under partial interaction, the hourly vertical thermal displacements findings are presented to more visualize the design life of such constructions, as well as, the economic aspects as regards to climatic impacts.
Basalt fiber-reinforced polymer (BFRP) is adopted widely in recent years in many countries to reh... more Basalt fiber-reinforced polymer (BFRP) is adopted widely in recent years in many countries to rehabilitate or strengthen structural elements such as reinforced concrete (RC) beams because it is cheap and it has stellar mechanical performance. By activating the finite element (FE) simulation, the present research submits an extensive study on the strengthening and rehabilitation of damaged full-scale RC beams due to corrosions in the main reinforcement caused by BFRP sheets. Different parameters were taken into consideration such as corrosion grade, BFRP wrapping schemes, and the number of layers. The flexural performance of the models that build up as the control model and the damaged and the repaired methodologies by BFRP that are adopted and tested by others under the effects of four-point static loadings were also underwent examination. The full interaction at BFRP-concrete interface and the full bonding between sheets presupposed were investigated for all models. The numerical a...
Comparison of error estimation methods and adaptivity for plane stress/strain problems
Structural Engineering and Mechanics, 2003
ABSTRACT This paper deals with adaptive finite element analysis of linearly elastic structures us... more ABSTRACT This paper deals with adaptive finite element analysis of linearly elastic structures using different error estimators based on flux projection (or best guess stress values) and residual methods. Presentations are given on a typical h-type adaptive analysis, a mesh refinement scheme and the coupling of adaptive finite element analysis with automatic mesh generation. Details about different error estimators are provided and their performance, reliability and convergence are studied using six node quadratic triangular elements. Several examples are presented to demonstrate the reliability of different error estimators.
The use of composite structures is increasingly present in civil building works. Composite Box Gi... more The use of composite structures is increasingly present in civil building works. Composite Box Girder Bridges (CBGB), particularly, are study of effect of shear connector's numbers and distribution on the behavior of CBGBs is submitted. A Predicti structures consisting of two materials, both connected by metal devices known as shear connectors. The main functions of these connectors are to allow for the joint behavior of the girder-deck, to restrict longitudinal slipping and uplifting at the element's interface and to take shear forces. This paper presents 3D numerical models of CBGBs to simulate their actual structural behavior, with emphasis on the girder-deck interface. Additionally, a Prediction of several FE models is assessed against the results acquired from a field test. A number of factors are considered, and confirmed through experiments, especially full shear connections, which are obviously essential in composite box girder. A good representation for shear connectors by suitable element type is considered. Numerical predictions of vertical displacements at critical sections fit fairly well with those evaluated experimentally. The agreement between the FE models and the experimental models show that the FE model can aid engineers in design practices of box girder bridges. Preliminary results indicate that number of shear studs can be significantly reduced to facilitate adoption of a new arrangement in modeling CBGBs with full composition. However, a further feasibility study to investigate the practical and economic aspects of such a remedy is recommended, and it may represent partial composition in such modeling.
This paper deals with the structural optimization of trusses by maximizing the structural fundame... more This paper deals with the structural optimization of trusses by maximizing the structural fundamental frequency while maintaining a constant total structure weight or minimizing the structure weight while keeping the structural fundamental frequency over a limited value. The fundamental concept is to find shape and dimensions of trusses in which system vibration characteristic is improved. Natural frequencies are determined using matrix-displacement method. The applicability, simplicity and effectiveness of the genetic algorithm based optimization are demonstrated. A carefully defined, unambiguous benchmark example is presented and studied with independent verification to highlight the various features of the truss optimization process
Today's high-strength materials allow for significant increases in working and limit stresses... more Today's high-strength materials allow for significant increases in working and limit stresses. To fully exploit material improvements as weight savings on structures, it is desirable to enhance the performance of structural components. The work presented in this paper proposes that the buckling behavior of cold form steel columns may be effectively improved without increased material volume. In order to achieve this goal, optimization algorithm which integrates finite strip analysis, geometric modeling, semi analytical sensitivity analysis and sequential quadratic mathematical programming methods can be used to find an optimum cross section of cold-formed steel columns under axial compression. The objective is the maximization of the critical buckling load with constraints on the volume of material used. Several examples are included to illustrate advantage of the optimization. The post buckling performance of optimized cold form steel columns was also investigated using nonline...
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Papers by Mustafa Özakça