• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.1
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• pp.79-90
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• 2002

The structural analysis such as rigid frame analysis has been used for the design of cut and cover tunnel due to its simplicity and convenience. This analysis, however, could not account for the geometrical factors such as interface elements, slope of excavation plane, distance between lining and excavation plane, etc. To develop the analysis technique and design technology for the cut and cover tunnel, in this study, the numerical analyses considering not only geometrical but geotechnical factors are conducted. Especially, the effects on the mechanical behaviors of cut and cover tunnel due to the slope of excavation plane and the distance between lining and excavation plane are mainly focused in this study.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.177-184
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• 1997

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.13-24
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• 1993

The tangent stiffness matrices of the plane frame and the thin-walled space frame are derived by using the principle of virtual displacement. In case of the plane frame, the shape function and stiffness matrices are presented for the rigid-hinged condition. For the unsymmetric thin-walled space frame, the elastic and geometric stiffness matrices in three cases of the unrestrained torsion, the restrained torsion, and the restrained anti unrestrained torsion are evaluated by using the various Hermitian polynomials as the shape function. Numerical examples for the lateral buckling analysis of the space frames and the circular arch illustrate the accuracy and convergence characteristics of the derived formulations.

• Composites Research
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• v.23 no.5
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• pp.8-14
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• 2010

Three types of glass woven fabrics (plain, balanced twill, and unbalanced twill) having various sample sizes and aspect ratios were tested using the bias-extension tests. Real-time deformation images, force, and displacement data were collected. For the bias-extension test, the shear angle of the fabrics from the equation based on the crosshead displacement and fabric size was compared with direct manual measurements of the warp and weft angles as well as the optical measurement software. To determine the shear force, an analytical equation was introduced considering the kinematics of the bias-extension test. The obtained shear behaviors were further compared with the results by the trellis-frame test. The optical measurement methods showed that the mathematical method was reasonable before the shear angle of the fabrics reaches $30^{\circ}$ in the bias-extension tests. Also, the bias-extension test gave consistent behaviors with the trellis-frame test only for isotropic and homogeneous fabrics such as balanced plain and twill weaves.

• Steel and Composite Structures
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• v.9 no.4
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• pp.381-395
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• 2009

This paper presents the details of an advanced Finite Element (FE) analysis of a plane steel portal frame with semi-rigid beam-to-column connections subjected cyclic loading. In spite of several component models on cyclic behaviour of connections presented in the literature, works on numerical investigations on cyclic behaviour of full scale frames are rather scarce. This paper presents the evolution of an FE model which deals comprehensively with the issues related to cyclic behaviour of full scale steel frames using ABAQUS software. In the material modeling, combined kinematic/isotropic hardening model and isotropic hardening model along with Von Mises criteria are used. Connection non-linearity is also considered in the analysis. The bolt slip which happens in friction grip connection is modeled. The bolt load variation during loading, which is a pivotal issue in reality, has been taken care in the present model. This aspect, according to the knowledge of the authors, has been first time reported in the literature. The numerically predicted results using the methodology evolved in the present study, for the cyclic behaviour of a cantilever beam and a rigid frame, are validated with experimental results available in the literature. The moment-rotation and deflection responses of the evolved model, match well with experimental results. This proves that the methodology for evolving the steel frame and connection model presented in this paper is closer to real frame behaviour as evident from the good comparison and hence paves the way for further parametric studies on cyclic behaviour of flexibly connected frames.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.7
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• pp.65-72
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• 2009

Laser interferometry is widely used as a measuring system in many fields because of its high resolution and its ability to measure a broad area in real-time all at once. In conventional laser interferometry, for example out-of-plane ESPI (Electronic Speckle Pattern Interferometry), in plane ESPI, shearography and holography, it uses PZT or other components as a phase shift instrumentation to extract 3-D deformation data, vibration mode and others. However, in most cases PZT has some disadvantages, which include nonlinear errors and limited time of use. In the present study, a new type of laser interferometry using a laser diode is proposed. Using Laser Diode Sinusoidal Phase Modulating (LD-SPM) interferometry, the phase modulation can be directly modulated by controlling the laser diode injection current thereby eliminating the need for PZT and its components. This makes the interferometry more compact. This paper reports on a new approach to the LD (Laser Diode) Modulating interferometry that involves four-frame phase shift method. This study proposes a four-frame phase mapping algorithm, which was developed to have a guaranteed application, to stabilize the system in the field and to be a user-friendly GUI. In this paper, the theory for LD wavelength modulation and sinusoidal phase modulation of LD modulating interferometry is shown. Using modulating laser and research of measurement algorithm does comparison with existent ESPI measurement algorithm. Algorithm measures using GPIB communication through most LabVIEW 8.2. GPIB communication does alteration through PC. Transformation of measurement object measures through modulating laser algorithm that develops. Comparison of algorithm of modulating laser developed newly with existent PZT algorithm compares transformation price through 3-D. Comparison of 4-frame phase mapping, unwrapping, 3-D is then introduced.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.13-24
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• 1988

A geometrically nonlinear analysis procedure for plane frame structures in order to study the static and dynamic post-buckling behavior of these structures subjected to circulatory forces is presented. The elastic and geometric stiffness matrices, the mass matrix and load correction stiffness matrix are derived from the extended virtual work principle, where the tangent stiffness matrix becomes non-symmetric due to the effects of non-conservative circulatory forces. The dynamic analysis of plane frame structures subjected to circulatory forces in pre- and post-buckling ranges is carried out by integrating the equations of motion directly by the numerically stable Newmark method. Numerical results are presented in order to demonstrate the vality and accuracy of the proposed procedure.

• Transactions of Materials Processing
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• v.20 no.2
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• pp.104-109
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• 2011

The metal front case of a mobile phone is manufactured by press forming and welding of thin metal sheets. Twisting of the frame after the forming process is one of main obstacle for the assembly with reinforcement by welding. This study introduces a method preventing twisting of the metal front case frame in press forming. The spring-back after forming produces twisting of the frame, which leads to a low structural stiffness. To reduce twisting, connectors are required to reinforce the structural stiffness of the frame. In this study, the twisting profile is evaluated using a finite element(FE) analysis for various connector shapes. The actual connector shape is determined by minimization of the frame twisting within the tolerance of the FE-analysis. To verify the validity of the proposed blank shape, a forming experiment is performed and the twisting profile is measured using a 3D laser scanning method. The dimensional accuracy is found to be within the tolerance and in good agreement with the FE-analysis.

• Structural Engineering and Mechanics
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• v.46 no.2
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• pp.213-229
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• 2013

Although performance based assessment procedures are mainly developed for reinforced concrete and steel buildings, URM (Unreinforced Masonry) buildings occupy significant portion of buildings in earthquake prone areas of the world as well as in IRAN. Variability of material properties, non-engineered nature of the construction and difficulties in structural analysis of masonry walls make analysis of URM buildings challenging. Despite sophisticated finite element models satisfy the modeling requirements, extensive experimental data for definition of material behavior and high computational resources are needed. Recently, nonlinear equivalent frame models which are developed assigning lumped plastic hinges to isotropic and homogenous equivalent frame elements are used for nonlinear modeling of URM buildings. The equivalent frame models are not novel for the analysis of masonry structures, but the actual potentialities have not yet been completely studied, particularly for non-linear applications. In the present paper an effective tool for the non-linear static analysis of 2D masonry walls is presented. The work presented in this study is about performance assessment of unreinforced brick masonry buildings through nonlinear equivalent frame modeling technique. Reliability of the proposed models is tested with a reversed cyclic experiment conducted on a full scale, two-story URM building at the University of Pavia. The pushover curves were found to provide good agreement with the experimental backbone curves. Furthermore, the results of analysis show that EFM (Equivalent Frame Model) with Dolce RO (rigid offset zone) and shell element have good agreement with finite element software and experimental results.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.04a
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• pp.105-112
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• 1994

In a local vibration analysis of a large steel frame, a large eigenvalue problem results. Due to computer storage and the expense of a complete solution, it is desirable to minimize the size of the resulting matrices. A new and efficient method of local vibration analysis for large steel frames is presented. It reduces the order of dynamic matrices by dynamic condensation method. Examples are given for local vibration of a plane frame. Results are compared to the complete solution of the full eigenvalue problem.