• Journal of the Society of Naval Architects of Korea
• /
• v.36 no.3
• /
• pp.122-133
• /
• 1999

Overlap, excessive wide gaps, and errors between blocks during erection process increases cost and man-hour. In this paper, a system to simulate the assembly process is suggested and a plane block assembly of welding deformation with gravity is simulated in consideration of assembly order, deformations and errors occurring in the cutting and forming processes are not considered and welding deformations are acquired by equivalent stiffness and load method from experiments and hull double bottom plane block is assembled on a assembly order by panel method. It is certified that according to the order of assembly, intermediate product shape affects rigidity which affects welding deformations. Assembly order must be considered in the assembly process. It is certified that the gravity has important role in the assembly process.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.2 no.1
• /
• pp.95-111
• /
• 1998

In this study, the concepts and procedures of the seismic damage analysis methods are examined for both the element-level and the system-level. The seismic damage analysis at the element-level is performed for several example structures using existing method for structural elements or single-degree-of-freedom (SDOF) systems such as the Park and Ang method. In order to analyze seismic damage at the system-level, two types of procedures are used. In the first type of procedure, the system-level seismic responses can be estimated by using the system representative response method(SRRM), or the equivalent SDOF system response method (ESDOF-SRM). Then, the system-level seismic damage is analyzed from the system-level seismic responses using existing method for structural elements or SDOF systems. IN the second type of procedure, the system-level seismic damages are analyzed using the element damage combination method (EDCM) combing the element-level damage indices determined by existing method. To compare tendency of the seismic damage analysis using each methods, example analysis is accomplished for several cases of different structures and different earthquake excitation.

• Magazine of the Korea Concrete Institute
• /
• v.8 no.3
• /
• pp.147-155
• /
• 1996

In this study a model for the constitutive relation of a plane concrete is proposed using a micromechariical model. In this model a precursor crack is assumed to exist in the aggregate-cement paste interface, and the LEFM is used to predict the nucleation of the bond cracks and the grow th of mortar cracks. For computational convenience the bond crack-mortar crack configuration is transformed into a straight crack with a point force in the middle. 'The overall compliance and the cons,titutive relation are predicted from the damage due to microcracks, and the predicted stress-strain curves are compared with some experimental data. According to the results, the model predictions are better for under tensile loading than under compression, for high, strength concrete than for normal strength concrete.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.3 s.49
• /
• pp.77-84
• /
• 2006

Unlike homogeneous material structure, the behavior of masonry structure is not perfectly elastic even in the range of small deformations because it is a non-homogeneous and anisotropic composite structural material, consisting of masonry units, mortar, and grout. This paper proposes a simplified way of investigating the evolution of the deformation and damage of the structure subjected to a series of successive ground motions with varying shaking. Especially, the most simple but useful algorithm of Fast Fourier Transformation (FFT) has been adopted to investigate the evolution of the deformation and damage of the structure tested on the shaking table. Moreover, the development of a hi-linear curve for an equivalent SDOF system which is obtained by exploiting the frequency and stiffness relationship was discussed. Finally, some important findings related to inelastic properties of the URM are summarized.

• Magazine of the Korea Concrete Institute
• /
• v.10 no.6
• /
• pp.261-268
• /
• 1998

Deflections due to shrinkage are frequently ignored in design calculation. Especially for thin member, shrinkage often causes considerable deformations as wellas appreciable stress changes. Several methods for computing shringkage curvature have been proposed by many researchers. Some of the approximte methods widely used in the recent years are the equivalent tensile force method, Miller's method and Branson's method. These methods were, however, somewhat oversimplified and could be too conservative in the case of well cured concrete structure. In this paper, an approximate method for computing shrinkage curvature and deflection is proposed. Curvature due to shrinkage is derived from the requirements of strain compatibility and equilibrium of a section and the age-adjusted effective modulus method. The proposed method is verified by comparison with several experimental measurements. The correlations between calculated and measured curvatures is very good.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.17 no.2
• /
• pp.89-99
• /
• 1997

Although discontinuously reinforced metal matrix composite(MMC) is one of the most promising materials for applications of aerospace, automotive industries, the thermal residual stresses developed in the MMC due to the mismatch in coefficients of thermal expansion between the matrix and the fiber under a temperature change has been pointed out as one of the serious problem in practical applications. There are very limited nondestructive techniques to measure the residual stress of composite materials. However, many difficulties have been reported in their applications. Therefore it is important to establish analytical model to evaluate the thermal residual stress of MMC for practical engineering application. In this study, an elastic model is developed to predict the average thermal residual stresses in the matrix and fiber of a misoriented short fiber composite. The thermal residual stresses are induced by the mismatch in the coefficient of the thermal expansion of the matrix and fiber when the composite is subjected to a uniform temperature change. The model considers two-dimensional in-plane fiber misorientation. The analytical formulation of the model is based on Eshelby's equivalent inclusion method and is unique in that it is able to account for interactions among fibers. This model is more general than past models to investigate the effect of parameters which might influence thermal residual stress in composites. The present model is to investigate the effects of fiber volume fraction, distribution type, distribution cut-off angle, and aspect ratio on thermal residual stress for in-plane fiber misorientation. Fiber volume fraction, aspect ratio, and distribution cut-off angle are shown to have more significant effects on the magnitude of the thermal residual stresses than fiber distribution type for in-plane misorientation.