• Structural Engineering and Mechanics
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• v.67 no.3
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• pp.291-300
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• 2018

In this work, a new trigonometry theory of shear deformation is developed for the static analysis of thick isotropic beams. The number of variables used in this theory is identical to that required in the theory of Euler-Bernoulli, sine function is used in the displacement field in terms of the coordinates of the thickness to represent the effects of shear deformation. The advantage of this theory is that shear stresses can be obtained directly from the relationships constitute, while respecting the boundary conditions at the free surface level of the beam. Therefore, this theory avoids the use of shear correction coefficients. The differential equilibrium equations are obtained using the principle of virtual works. A thick isotropic beam is considered, whose numerical study to show the effectiveness of this theory.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.17-23
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• 2004

The performance and life of a die are influenced by the machining methods. In order to examine the effects of machining methods on surface charactenstics, simple experiments are devised and performed. A die steel STD11, commonly used as a die material in press working, is selected. Three ways of machining methods to manufacture a die are considered. Those are (1) milling and then grinding, (2) wire-cut electric discharge dachining (W-EDM) and (3) heat treatment after W-EDM. The resulting surface roughnesses are measured. Also, the changes of surface microstructures are investigated using the scanning electron microscope(SEM) with energy dispersive X-ray spectrometer(EDS) and the results are discussed in details.

• Geotechnical Engineering
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• v.8 no.4
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• pp.51-66
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• 1992

As the scale of public works get recently larger and diversified. the construction of retain- ing walls is required for the effective use of land. In the design of the retaining wall, the reliability and fitness of the retaining wall itself are regarded prudently although there is a tendency to ignore the importance of backfill. In this study, the experiments under various conditions such as repetition-continuity-load, roller-press load, and working space of backfill, are carried out using a model retaining wall similar to the real system. The experimental roes tilts are interpreted theoretically, Using a computer program, the experimental results are analyzed and compared with other theoretical wonts.

• Structural Engineering and Mechanics
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• v.6 no.4
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• pp.427-437
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• 1998

Flat plate constructions are structural systems which are directly placed on columns without any beams. Various solution methods have been introduced for the solution of flat plate structures under horizontal and vertical loads. In most of these solution methods, models comprising of one column and one plate have been studied. In other solutions, however, co-behavior of two reciprocal columns has been investigated. In this study, interrelations of all the columns on one storey have been examined. At the end of the study structure consisting of nine columns and four plates has been chosen as a model. Then unit moment has been successively applied to each of these columns and unit moments carried over the other columns have been found. By working out solutions far plates and columns varying in ratio, carry-over factors have been found and these factors given in tables. In addition, fixed-end moment factors on the columns arising due to vertical load were also calculated. Then citing slope-deflection equations to which these results could be applied, some examples of moment and horizontal equilibrium equations have been given.

• Advances in robotics research
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• v.2 no.1
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• pp.13-31
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• 2018

This paper presents the performance of Teaching-Learning-Based Optimization (TLBO) algorithm for optimum static balancing of a robot manipulator. Static balancing of robot manipulator is an important aspect of the overall robot performance and the most demanding process in any robot system to match the need for the production requirements. The average force on the gripper in the working area is considered as an objective function. Length of the links, angle between them and stiffness of springs are considered as the design variables. Three robot manipulator configurations are optimized. The results show the better or competitive performance of the TLBO algorithm over the other optimization algorithms considered by the previous researchers.

• Structural Engineering and Mechanics
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• v.58 no.4
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• pp.627-639
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• 2016

The analysis of thermally induced stresses in engineering structures is a very important and necessary task with respect to design and modeling of pressurized containers, heat exchangers, aircrafts segments, etc. to prevent them from failure and improve working conditions. So, the purpose of this study is to investigate elasto-plastic thermal stresses and deformations in a thin annular plate embedded into rigid container. To this end, analytical research devoted to mathematically and physically rigorous stress/strain analysis is performed. In order to evaluate the effect of logarithmic thermal gradients, commonly applied to structures which incorporate thin plate geometries, different thermal parameters such as temperature mismatch and varying constraint temperature were introduced into the model of elastic perfectly-plastic annular plate obeying the von Mises yield criterion with its associated flow rule. The results obtained may be used in sensitive to temperature differences aircraft structures where the thermal effects on equipment must be kept in mind.

• Steel and Composite Structures
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• v.12 no.6
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• pp.465-489
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• 2012

Residual stresses play important role for design of steel structural members. Cold formed sections usually have residual stresses caused by roll forming. When compared to stresses caused by the working load, especially for compressed members, the effects of residual stresses can be favorable or unfavorable depending on magnitude, orientation and distribution of these stresses. The research presented in this paper includes experimental investigations of residual stresses, initial imperfections and material properties on cold formed carbon steel open cross sections. Experimental results have been compared to results obtained in similar tests with stainless and high strength steel cross sections. Theoretical and experimental research, conducted for cold formed open cross sections, are important for design of axially compressed members. This paper presents two methods of residual stresses investigation: magnetic method and method of pre-drilled holes and obtained results have been compared with results of residual stresses from other authors.

• Ocean Systems Engineering
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• v.2 no.4
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• pp.271-287
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• 2012

Due to its large size, a ship is first divided into scores of blocks and then each block is constructed through various shops, such as the assembly shop, the painting shop, and the outfitting shop. However, each block may not be directly moved to the next shop and may be temporarily laid at a block stockyard because the working time in each shop is different from each other. If blocks are laid at the block stockyard without any planning, the rearrangement of the blocks by a transporter is required because the blocks have the different in and out time. In this study, a block layout method based on the genetic algorithm was proposed in order to minimize the rearrangement of the blocks in the block stockyard. To evaluate the applicability of the proposed method, it was applied to simple layout problems of the block stockyard. The result shows that the proposed method can yield a block layout that minimizes the total relocation cost of moving obstacle blocks in the block stockyard.

• Wind and Structures
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• v.10 no.2
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• pp.177-208
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• 2007

Few mathematical methods attracted theoretical and applied researches, both in the scientific and humanist fields, as the Proper Orthogonal Decomposition (POD) made throughout the last century. However, most of these fields often developed POD in autonomous ways and with different names, discovering more and more times what other scholars already knew in different sectors. This situation originated a broad band of methods and applications, whose collation requires working out a comprehensive viewpoint on the representation problem for random quantities. Based on these premises, this paper provides and discusses the theoretical foundations of POD in a homogeneous framework, emphasising the link between its general position and formulation and its prevalent use in wind engineering. Referring to this framework, some applications recently developed at the University of Genoa are shown and revised. General remarks and some prospects are finally drawn.

• Smart Structures and Systems
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• v.24 no.1
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• pp.37-52
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• 2019

Despite its success and wide application, base isolation system has been challenged for its passive nature, i.e., incapable of working with versatile external loadings. This is particularly exaggerated during near-source earthquakes and earthquakes with dominate low-frequency components. To address this issue, many efforts have been explored, including active base isolation system and hybrid base isolation system (with added controllable damping). Active base isolation system requires extra energy input which is not economical and the power supply may not be available during earthquakes. Although with tunable energy dissipation ability, hybrid base isolation systems are not able to alter its fundamental natural frequency to cope with varying external loadings. This paper reports an overview of new adventure with aim to develop adaptive base isolation system with controllable stiffness (thus adaptive natural frequency). With assistance of the feedback control system and the use of smart material technology, the proposed smart base isolation system is able to realize real-time decoupling of external loading and hence provides effective seismic protection against different types of earthquakes.