• Title/Summary/Keyword: ultimate capacity

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Characteristic of a Soft Ground Behavior Subjected to Static and Dynamic Loads (A Study on the Model Test) (정하중 및 동하중이 작용하는 연약지반의 거동특성(비교모형실험))

  • Kim, Jong-Ryeol;Kang, Jin-Tae;Lee, Chi-Yeal;Part, Yong-Myun;Jeong, Jea-Hoon
    • Journal of the Korean Geotechnical Society
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    • v.24 no.1
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    • pp.111-118
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    • 2008
  • In the study a 2 dimensional model test was executed to grasp the effect of the taking load of equipments on the ground when improving a soft ground like dredging reclaimed ground. The static load and the dynamic load in the consolidated model ground was $0.02kg/cm^2,\;0.03kg/cm^2\;and\;0.04kg/cm^2$ respectively. After consolidating far two months by consolidation load of $0.02kg/cm^2,\;0.03kg/cm^2\;and\;0.04kg/cm^2$ respectively, the ultimate bearing capacity was $0.16kg/cm^2,\;0.19kg/cm^2,\;0.24kg/cm^2$ respectively. And the energy price of dynamic load test at the same point as the settlement of static load test indicated $E=336{\sim}945kg{\cdot}cm,\;E=252{\sim}780kg{\cdot}cm\;and\;E=323{\sim}727kg{\cdot}cm$ for each consolidation load. When the static load and the dynamic load operated at the same ground condition, the heaving quantity was bigger in the case of the dynamic load than in the case of the static load, and the horizontal displacement quantity the in the case of dynamic load was exhibited very deficiently compared to the quantity in the case of static load test.

Dynamic p-y Backbone Curves for a Pile in Saturated Sand (포화 사질토 지반에서의 동적 p-y 중추곡선)

  • Yang, Eui-Kyu;Yoo, Min-Taek;Kim, Hyun-Uk;Kim, Myoung-Mo
    • Journal of the Korean Geotechnical Society
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    • v.25 no.11
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    • pp.27-38
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    • 2009
  • In this study, a series of 1 g shaking table model pile tests were carried out in saturated dense and loose sand to evaluate dynamic p-y curves for various conditions of flexural stiffness of a pile shaft, acceleration frequency and acceleration amplitude for input loads. Dynamic p-y backbone curve which can be applied to pseudo static analysis for saturated dense sand was proposed as a hyperbolic function by connecting the peak points of the experimental p-y curves, which corresponded to maximum soil resistances. In order to represent the backbone curve numerically, empirical equations were developed for the initial stiffness ($k_{ini}$) and the ultimate capacity ($p_u$) of soils as a function of a friction angle and a confining stress. The applicability of a p-y backbone curve was evaluated based on the centrifuge test results of other researchers cited in literature, and this suggested backbone curve was also compared with the currently available p-y curves. And also, the scaling factor ($S_F$) to account for the degradation of soil resistance according to the excess pore pressure was developed from the results of saturated loose sand.

Stress-strain Relations of Concrete Confined with Tubes Having Varying GFRP Layers (수적층 및 필라멘트 와인딩을 이용한 GFRP튜브로 구속된 콘크리트의 압축 거동)

  • Lee, Sung Woo;Choi, Sokhwan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.6A
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    • pp.861-872
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    • 2008
  • Concrete-filled glass fiber reinforced polymer tubes are often used for marine structures with the benefit of good durability and high resistance against corrosion under severe chemical environment. Current research presents results of a comprehensive experimental investigation on the behavior of axially loaded circular concrete-filled glass fiber reinforced polymer tubes. This paper is intended to examine several aspects related to the usage of glass fiber fabrics and filament wound layers used for outer shell of piles subjected to axial compression. The objectives of the study are as follows: (1) to evaluate the effectiveness of filament winding angle of glass fiber layers (2) to evaluate the effect of number of GFRP layers on the ultimate load and ductility of confined concrete (3) to evaluate the effect of loading condition of specimens on the effectiveness of confinement and failure characteristics as well, and (4) to propose a analytical model which describes the stress-strain behavior of the confined concrete. Three different types of glass fiber layers were chosen; fabric layer, ${\pm}45^{\circ}$ filament winding layer, and ${\pm}85^{\circ}$ filament winding layer. They were put together or used independently in the fabrication of tubes. Specimens that have various L:D ratios and different diameters have also been tested. Totally 27 GFRP tube specimens to investigate the tension capacity, and 66 concrete-filled GFRP tube specimens for compression test were prepared and tested. The behavior of the specimens in the axial and transverse directions, failure types were investigated. Analytical model and parameters were suggested to describe the stress-strain behavior of concrete under confinement.

A Study on the Problem and Improvement of Distribution Structure of Farm Product in Korea (우리나라 농산물 유통구조의 문제점과 개선에 관한 연구)

  • Chol, Soo-Hwan;Kim, Joong-Won;Kim, Kyung-Rok;Lee, Young-Suk
    • The Korean Journal of Franchise Management
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    • v.2 no.2
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    • pp.70-83
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    • 2011
  • The number of agricultural products due to open in response to international competitiveness of the farming press and the need for structural adjustment in agriculture and in agricultural crops receive a fair market price, fair trade, such as improving efficiency sidaejeo appropriate response to the request of the government must have. For this purpose, compared to the communist bojaphan agricultural water efficiently changing the structure of the distribution, agricultural products originating from the acquisition phase choice of shipping a stable product supply and plans to expand production system to induce a smooth supply of agricultural products, expand processing capacity and sales control should be. Also, in the distribution process by eliminating various immoral conduct commerce retail establishment and enforcement of policies for efficient and accurate distribution statistics, information is needed. The ultimate goal of agricultural restructuring and ensure fair price for producers sangpuui and improvement of production facilities for maximizing and affordable for consumers, according to your preferences to receive the best offer will be Foo. Therefore, management increases the efficiency of just distribution costs, or margins, lowering the improvement is not practical to restructure the distribution structure of costs for the best product and must supply the next country of agricultural products, strengthen the consumer's purchase desire to meet will be.

Evaluation of Steel Tube Connection in Precast Concrete Double Wall System (프리캐스트 콘크리트 더블월 시스템의 각형 강관 연결부 성능평가 )

  • Yujae Seo;Hyunjin Ju
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.27 no.2
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    • pp.25-32
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    • 2023
  • In this study, a double wall system is introduced, which was invented to simplify the complicated manufacturing process of the existing precast concrete (PC) double wall systems and to remove defects such as laitance that may occur during the production of concrete panels. An experimental study was conducted to investigate the tensile resisting capacity of the steel tube which is embedded in the precast concrete panel to keep the spacing between PC panels and to prevent damage of the PC panels during transportation and casting concrete onsite. The experiment was planned to determine the detail of effective steel tube connection considering the steel plate treatment method according to the formation of the opening, the presence of embedded concrete, and the reinforcement welding for additional dowel action as key variables. As a result, the ultimate tensile strength increased by 20-30% compared to the control specimen (ST) except for the steel tube specimen (ST_CP) which has steel plates bent inward at the end part of the steel tube. Since the specimen (ST_CON) filled with concrete inside the control specimen has no additional process and cost for the steel tube connections compared to the control specimen during the production of the developed double wall system, it is determined to be the appropriate detail of steel tube connection.

An Experiment on Redundancy in Continuous Span Two-Girder Bridge - Effects of Lateral Bracing (연속 2-거더교의 여유도 평가 실험 - 수평브레이싱의 효과)

  • Park, Yong-Myung;Joe, Woom-Do-Ji;Hwang, Min-Oh;Yoon, Tae-Yang
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.4A
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    • pp.417-429
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    • 2008
  • This paper presents an experimental result to evaluate the redundancy in continuous span two plate-girder bridges which are generally classified as a non-redundant load path structure. The experiments were performed when one of the two girders is seriously cracked. To estimate the effects of bottom lateral bracing on the redundancy, the experiment variable was considered as the bottom lateral bracing, and two 1/5-scaled bridge specimens with and without lateral bracing system were fabricated. The ultimate loading tests were conducted on the damaged specimens with an induced crack at a girder in the side span. The test results showed that the load carrying capacity of damaged specimen with bracing was about 1.2 times higher than that without bracing. To evaluate the redundancy in each specimen, numerical analysis was performed to calibrate the difference of dead load between the actual bridge and the test specimens. When the dead load calibration is considered, the results showed that a continuous span two-girder bridges have a reasonable redundancy even without lateral bracing. Especially, the level of redundancy is increased by about 1.8 times when the lateral bracing is provided.

Mechanical properties of new stainless steel-aluminum alloy composite joint in tower structures

  • Yingying Zhang;Qiu Yu;Wei Song;Junhao Xu;Yushuai Zhao;Baorui Sun
    • Steel and Composite Structures
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    • v.49 no.5
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    • pp.517-532
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    • 2023
  • Tower structures have been widely used in communication and transmission engineering. The failure of joints is the leading cause of structure failure, which make it play a crucial role in tower structure engineering. In this study, the aluminum alloy three tube tower structure is taken as the prototype, and the middle joint of the tower was selected as the research object. Three different stainless steel-aluminum alloy composite joints (SACJs), denoted by TA, TB and TC, were designed. Finite element (FE) modeling analysis was used to compare and determine the TC joint as the best solution. Detail requirements of fasteners in the TC stainless steel-aluminum alloy composite joint (TC-SACJ) were designed and verified. In order to systematically and comprehensively study the mechanical properties of TC-SACJ under multi-directional loading conditions, the full-scale experiments and FE simulation models were all performed for mechanical response analysis. The failure modes, load-carrying capacities, and axial load versus displacement/stain testing curves of all full-scale specimens under tension/compression loading conditions were obtained. The results show that the maximum vertical displacement of aluminum alloy tube is 26.9mm, and the maximum lateral displacement of TC-SACJs is 1.0 mm. In general, the TC-SACJs are in an elastic state under the design load, which meet the design requirements and has a good safety reserve. This work can provide references for the design and engineering application of aluminum alloy tower structures.

PRC Maritime Operational Capability and the Task for the ROK Military (중국군의 해양작전능력과 한국군의 과제)

  • Kim, Min-Seok
    • Strategy21
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    • s.33
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    • pp.65-112
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    • 2014
  • Recent trends show that the PRC has stepped aside its "army-centered approach" and placed greater emphasis on its Navy and Air Force for a wider range of operations, thereby reducing its ground force and harnessing its economic power and military technology into naval development. A quantitative growth of the PLA Navy itself is no surprise as this is not a recent phenomenon. Now is the time to pay closer attention to the level of PRC naval force's performance and the extent of its warfighting capacity in the maritime domain. It is also worth asking what China can do with its widening naval power foundation. In short, it is time to delve into several possible scenarios I which the PRC poses a real threat. With this in mind, in Section Two the paper seeks to observe the construction progress of PRC's naval power and its future prospects up to the year 2020, and categorize time frame according to its major force improvement trends. By analyzing qualitative improvements made over time, such as the scale of investment and the number of ships compared to increase in displacement (tonnage), this paper attempts to identify salient features in the construction of naval power. Chapter Three sets out performance evaluation on each type of PRC naval ships as well as capabilities of the Navy, Air Force, the Second Artillery (i.e., strategic missile forces) and satellites that could support maritime warfare. Finall, the concluding chapter estimates the PRC's maritime warfighting capability as anticipated in respective conflict scenarios, and considers its impact on the Korean Peninsula and proposes the directions ROK should steer in response. First of all, since the 1980s the PRC navy has undergone transitions as the focus of its military strategic outlook shifted from ground warfare to maritime warfare, and within 30 years of its effort to construct naval power while greatly reducing the size of its ground forces, the PRC has succeeded in building its naval power next to the U.S.'s in the world in terms of number, with acquisition of an aircraft carrier, Chinese-version of the Aegis, submarines and so on. The PRC also enjoys great potentials to qualitatively develop its forces such as indigenous aircraft carriers, next-generation strategic submarines, next-generation destroyers and so forth, which is possible because the PRC has accumulated its independent production capabilities in the process of its 30-year-long efforts. Secondly, one could argue that ROK still has its chances of coping with the PRC in naval power since, despite its continuous efforts, many estimate that the PRC naval force is roughly ten or more years behind that of superpowers such as the U.S., on areas including radar detection capability, EW capability, C4I and data-link systems, doctrines on force employment as well as tactics, and such gap cannot be easily overcome. The most probable scenarios involving the PRC in sea areas surrounding the Korean Peninsula are: first, upon the outbreak of war in the peninsula, the PRC may pursue military intervention through sea, thereby undermining efforts of the ROK-U.S. combined operations; second, ROK-PRC or PRC-Japan conflicts over maritime jurisdiction or ownership over the Senkaku/Diaoyu islands could inflict damage to ROK territorial sovereignty or economic gains. The PRC would likely attempt to resolve the conflict employing blitzkrieg tactics before U.S. forces arrive on the scene, while at the same time delaying and denying access of the incoming U.S. forces. If this proves unattainable, the PRC could take a course of action adopting "long-term attrition warfare," thus weakening its enemy's sustainability. All in all, thiss paper makes three proposals on how the ROK should respond. First, modern warfare as well as the emergent future warfare demonstrates that the center stage of battle is no longer the domestic territory, but rather further away into the sea and space. In this respect, the ROKN should take advantage of the distinct feature of battle space on the peninsula, which is surrounded by the seas, and obtain capabilities to intercept more than 50 percent of the enemy's ballistic missiles, including those of North Korea. In tandem with this capacity, employment of a large scale of UAV/F Carrier for Kill Chain operations should enhance effectiveness. This is because conditions are more favorable to defend from sea, on matters concerning accuracy rates against enemy targets, minimized threat of friendly damage, and cost effectiveness. Second, to maintain readiness for a North Korean crisis where timely deployment of US forces is not possible, the ROKN ought to obtain capabilities to hold the enemy attack at bay while deterring PRC naval intervention. It is also argued that ROKN should strengthen its power so as to protect national interests in the seas surrounding the peninsula without support from the USN, should ROK-PRC or ROK-Japan conflict arise concerning maritime jurisprudence. Third, the ROK should fortify infrastructures for independent construction of naval power and expand its R&D efforts, and for this purpose, the ROK should make the most of the advantages stemming from the ROK-U.S. alliance inducing active support from the United States. The rationale behind this argument is that while it is strategically effective to rely on alliance or jump on the bandwagon, the ultimate goal is always to acquire an independent response capability as much as possible.

Establishment of an Optimal Washing Condition of a High Temperature Steaming System for the Production of High Quality Pork (고품질 돈육 생산을 위한 고온증기세척수의 최적 조건)

  • Yang, H.S.;Jeong, J.Y.;Moon, S.H.;Park, G.B.;Joo, Seon-Tea
    • Journal of Animal Science and Technology
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    • v.49 no.1
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    • pp.121-128
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    • 2007
  • The objective of this study was to determine the efficacy of different water temperatures and time of spray-washing on the removal of bacteria contamination from surface of pork carcass and to obtain better meat quality with high temperature stream between 60 to 90℃ for the time ranged from 10 to 60 sec. Results showed that total plate counts were significantly decreased with increasing steam temperature(P<0.05). Similar results were found with the spray time(P<0.05). The lightness(CIE L*) value was significantly increased in both loin and ham cuts over 80℃(P<0.05). Ultimate pH of muscle and water-holding capacity were decreased with increasing steam temperature(P<0.05). There was a significant difference in solubility of sarcoplasmic protein between 70℃ and 80℃ of the steam treatments with higher value at 70℃(P<0.05). Again, longer than 30 sec spray at 70℃ steam, the lightness value of pork was significantly increased(P<0.05), while pH and water-holding capacity of muscle were significantly decreased(P<0.05). Therefore, a desirable pork quality would be achieved with spray-steam washing at 70℃ for 20 sec on pork carcass.

Determination of cross section of composite breakwaters with multiple failure modes and system reliability analysis (다중 파괴모드에 의한 혼성제 케이슨의 단면 산정 및 제체에 대한 시스템 신뢰성 해석)

  • Lee, Cheol-Eung;Kim, Sang-Ug;Park, Dong-Heon
    • Journal of Korea Water Resources Association
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    • v.51 no.9
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    • pp.827-837
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    • 2018
  • The stabilities of sliding and overturning of caisson and bearing capacity of mound against eccentric and inclined loads, which possibly happen to a composite caisson breakwaters, have been analyzed by using the technique of multiple failure modes. In deterministic approach, mathematical functions have been first derived from the ultimate limit state equations. Using those functions, the minimum cross section of caisson can straightforwardly be evaluated. By taking a look into some various deterministic analyses, it has been found that the conflict between failure modes can be occurred, such that the stability of bearing capacity of mound decreased as the stability of sliding increased. Therefore, the multiple failure modes for the composite caisson breakwaters should be taken into account simultaneously even in the process of deterministically evaluating the design cross section of caisson. Meanwhile, the reliability analyses on multiple failure modes have been implemented to the cross section determined by the sliding failure mode. It has been shown that the system failure probabilities of the composite breakwater are very behaved differently according to the variation of incident waves. The failure probabilities of system tend also to increase as the crest freeboards of caisson are heightening. The similar behaviors are taken place in cases that the water depths above mound are deepening. Finally, the results of the first-order modal are quite coincided with those of the second-order modal in all conditions of numerical tests performed in this paper. However, the second-order modal have had higher accuracy than the first-order modal. This is mainly due to that some correlations between failure modes can be properly incorporated in the second-order modal. Nevertheless, the first-order modal can also be easily used only when one of failure probabilities among multiple failure modes is extremely larger than others.