• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.84-89
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• 2005

The double hull VLCC(Very Large Crude Oil Tanker) have been designed to have each four(4) longitudinal bulkheads and transverse bulkheads in general. Actually, the inside longitudinal bulkheads among four(4) longitudinal bulkheads, which are extended up to the end of the aft cargo hold for continuity of the members, have been designed with knuckled type inboard due to the narrowed hull shape at bottom region, but sometimes the straight type of longitudinal bulkheads were adopted based on the degree of the hull lines shape. However, regardless the type of longitudinal bulkheads, inside and outside longitudinal bulkheads conflict each other in aft cargo hold region This makes the structure more complex thus giving difficulties to structural design and production. Recently, a vessel of straight type was reported to have cracks on bracket end and tripping bracket toe in aft cargo hold region. As a solution to this problem, in designing the first 60m Beam VLCC, DSME developed a new cargo hold structure which is good in production and structural point of view by structural strength and fatigue analysis of fore and aft cargo hold.

• Structural Engineering and Mechanics
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• v.3 no.4
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• pp.341-358
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• 1995

The results of a series of ten W-shaped test specimens subjected to monotonic, quasi-static cyclic loading and fatigue type of loading in the form of constant amplitude tests are presented. The objectives were to assess and compare the rotation capacity and energy absorption of monotonically and cyclically loaded beams, and for the latter specimens to document the deterioration in the form of low cycle fatigue due to local buckling. In addition, strength and energy dissipation deterioration and damage models have been developed for the steel beam section under consideration. Finally, a generalized model which uses plate slenderness values and lateral slenderness is proposed for predicting rate in strength deterioration per reversal and cumulated damage after a given number of reversals.

• Structural Engineering and Mechanics
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• v.81 no.5
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• pp.551-563
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• 2022

Bolted connector could be an alternative to replace the conventional welded headed stud in steel-ultra high performance concrete (UHPC) lightweight composite structures. In this paper, a novel demountable bolted shear connector, consisting of a high-strength bolt (HSB) and a specially-designed nut which is pre-embedded in a thin UHPC slab, is proposed, which may result in the quick installation and disassembly, due to the mountable, demountable and reusable features. In order to study the shear behavior of the new type of bolted shear connector, static push-out tests were conducted on five groups of the novel demountable bolted shear connector specimens and one group of conventional welded headed stud specimen for comparison. The effect of the bolt shank diameter and aspect ratio of bolt on failure mode, shear stiffness, peak slip at the steel-UHPC interface, shear strength and ductility of novel bolted connectors is investigated. Additionally, design formula for the shear strength is proposed to check the suitability for assessment of the novel demountable bolted shear connectors.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.372-379
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• 2023

International oil prices are expected to increase from $85 a barrel this year to up to $100 a barrel in the second half of the year; this is likely to increase orders for offshore plants in the global market. One main characteristic of offshore plants is that a large helideck is located on the top side, and aluminum alloys are used as the basic material of the structure for weight reduction and corrosion resistance. Shipowners are increasing the size of helicopters to quickly evacuate lives in the event of an emergency, and the safety use load of devices that can stably secure helicopters to the deck is also required to increase. Owing to the nature of the aluminum material, the structural strength caused by welding is greatly reduced; therefore, the fixing device must be designed by embedding it in the deck and fixing it with bolts. In this study, a model applying aluminum alloy 6082-T6 was developed to develop a helicopter fastening device that can be used for large helidecks (diameter = 28 m). The developed item was verified through nonlinear structural strength calculation to satisfy the load used for the actual fastening condition. The load condition with a 45° showed a lower ultimate strength than the 90° case owing to local plastic collapse. The nonlinear structural collapse behavior showed a result similar to that of the experimental test. The main contents derived from this study are considered to be reference materials when evaluating the structural strength of similar aluminum equipment.

• Smart Structures and Systems
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• v.19 no.5
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• pp.499-512
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• 2017

Traditional structural dynamic analysis and Structural Health Monitoring (SHM) of large scale concrete civil structures rely on manufactured embedding transducers to obtain structural dynamic properties. However, the embedding of manufactured transducers is very expensive and low efficiency for signal acquisition. In dynamic structural analysis and SHM areas, piezoelectric transducers are more and more popular due to the advantages like quick response, low cost and adaptability to different sizes. In this paper, the applicable feasibility assessment of the designed "artificial" piezoelectric transducers called Concrete Piezoelectric Smart Module (CPSM) in dynamic structural analysis is performed via three major experiments. Experimental Modal Analysis (EMA) based on Ibrahim Time Domain (ITD) Method is applied to experimentally extract modal parameters. Numerical modal analysis by finite element method (FEM) modeling is also performed for comparison. First ten order modal parameters are identified by EMA using CPSMs, PCBs and FEM modeling. Comparisons are made between CPSMs and PCBs, between FEM and CPSMs extracted modal parameters. Results show that Power Spectral Density by CPSMs and PCBs are similar, CPSMs acquired signal amplitudes can be used to predict concrete compressive strength. Modal parameter (natural frequencies) identified from CPSMs acquired signal and PCBs acquired signal are different in a very small range (~3%), and extracted natural frequencies from CPSMs acquired signal and FEM results are in an allowable small range (~5%) as well. Therefore, CPSMs are applicable for signal acquisition of dynamic responses and can be used in dynamic modal analysis, structural health monitoring and related areas.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.411-412
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• 2009

The techniques of testing and controlling intensity of structural concrete involve many problems and difficulties on the construction site. Hence this study aims at evaluating intensity of structural concrete in order to verify on-site application and structural efficiency assessment using joint separation test body.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1174-1182
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• 2004

Recently, Self Piercing Rivet(SPR) has been spotlighted in the automotive industry as a substitutive resort of spot welding and has also been watched by the designer as lightening a car body due to their superior assembly processes. Fatigue behavior of SPR joint needs to be investigated experimentally and numerically to predict its structural stiffness and fatigue life. Testing of lap-shear specimens with various material combinations is performed to obtain the joining strength and the fatigue life of SPR connections. The simulation of SPR lap-shear specimens is also conducted to obtain the structural stiffness of SPR connections under different material combinations. A Finite element model of the SPR lap-shear specimen is developed using a FEMFAT SPR pre-processor. The fatigue lift of SPR specimen is predicted using a FEMFAT 4.4e based on the liner finite element analysis.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.448-452
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• 2008

2-stroke marine diesel engine has generally one exhaust valve and three fuel injection nozzle which are key component for engine's performance and combustion. Fuel injection and exhaust valve driving system are driven by rotating of camshaft. Rotation of crank shaft drives the cam shaft through gear train that is composed of $3{\sim}4$ gear wheels. Gear column supporting the gear wheel has to bear against the dynamics forces by engine running as well as gearing forces. In this paper, structural analysis for engine structure and fatigue strength assessment of welded joint is shown. Repeatedly full cyclic simulation during one cycle is performed to investigate the structural behavior of engine. Fatigue analysis is carried out based on IIW using submodeling technique to obtain more detailed stress distribution.

• Earthquakes and Structures
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• v.17 no.3
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• pp.283-295
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• 2019

During the seismic performance assessment of existing buildings, staircases are generally not taken into account as structural members but as dead load. Staircases, as secondary structural members, not only serve for connecting successive floors but also provide considerable amount of strength and stiffness to the building which can modify its seismic behaviour considerably. In this parametric study, the influence of staircases on the seismic response of substandard RC frame buildings which differ in number of storey and span, presence of staircase and its position has been examined. Modal Analyses and bi-directional Non-Linear Time History Analyses (NLTHA) were conducted to compare several engineering demand parameters (EDPs) such as inter-storey drift ratio (ISDR), floor accelerations, modal properties, member shear forces and plastic hinge distribution. Additionally, short column effect, variation in shear forces of columns that are attached to the staircase slab, failure and deformation in staircase models have also been investigated. As the staircase was considered in the analytical model, a different damage pattern can be developed especially in the structural components close to staircase.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1051-1055
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• 2003

Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Structural integrity assessment for the carbody by static load test has been performed up to date. In this study, to evaluate fatigue strength of the aluminum carbody of urban transit unit. a testing method to simulate dynamic loading condition was proposed and the fatigue strength of the carbody was evaluated. The dynamic load test results showed that the alternating stress ranges were different from the estimated ranges based on the static test results. Excessive stress ranges at the center are thought to come from the flexible motion of the carbody. published fatigue test data for aluminum components, but variation of alternating acceleration along the length due to flexibility of carbody yielded unexpected results. Because fatigue strength based on the static test results may be overestimated at the center, modification of testing method is necessary.