• 산업기술연구
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• 제26권B호
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• pp.93-99
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• 2006

Centrifuge model experiments were performed to investigate the confining effects of the sheet piles, installed to the sides of soft clay ground treated with sand compaction piles, on the bearing capacity and concentration ratio of composite ground. For the given g-level in the centrifuge model tests, replacement ratio of SCP and the width of surcharge loads on the surface of ground with SCP, the confining effects of installing the sheet piles on the edges of SCP ground on the bearing capacity, change of stress concentration ratio and failure mechanism were investigated. Kaolin, one of typical clay mineral, and Jumunjin standard sand were used as a soft clay ground and sand compaction pile irrespectively. As results of experiments, lateral confining effect by inserting the model sheet piles fixed to the loading plate was observed. For the strip surcharge loading condition, the yielding stress intensity in the form of the strip surcharge loads tends to increase with increasing the embedded depth of sheet piles. The stress concentration ratio was found not to be influenced consistently with the embedded depth of sheet piles whereas the effect of stress intensity on stress concentration ratio shows the general trend that values of stress concentration ratio are relatively high at the initial stage of loading and tend to decrease and converge to the certain values. For the failure mechanism in the case of reinforced with sheet piles, displacement behavior related to the punching failure, settlement right beneath the loading plate occurred since the soil was confined with sheet piles, was observed.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.555-564
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• 2006

The aim of this paper is to contribute to the efficient design of traffic light poles involved in vehicle frontal collisions by developing a computer-based, finite-element model capable of capturing the impact characteristics. This is achieved by using the available non-linear dynamic analysis software "LS-DYNA3D", which can accurately predict the dynamic response of both the vehicle and the traffic light pole. The fiber reinforced polymer(FRP) as a new pole's material is proposed in this paper to increase energy absorption capabilities in the case of a traffic pole involved in a vehicle head-on collision. Numerical analyses are conducted to evaluate the effects of key parameters on the response of the pole embedded in soil when impacted by vehicles, including: soil type(clay and sand) and pole material type(FRP and steel). It is demonstrated from the numerical analysis that the FRP pole-soil system has favorable advantages over steel poles, where the FRP pole absorbed vehicle impact energy in a smoother behavior, which leads to smoother acceleration pulse and less deformation of the vehicle than those encountered with steel poles. Also, it was observed that clayey soil brings a slightly more resistance than sandy soil which helps reducing pole movement at ground level. Finally, FRP pole system provides more energy absorbing leading to protection during minor impacts and under service loading, and remain flexible enough to avoid influencing vehicle occupants, thus reducing fatalities and injuries resulting from the crash.

• Advanced Composite Materials
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• 제16권4호
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• pp.269-282
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• 2007

Fully biodegradable high strength composites or 'advanced green composites' were fabricated using yearly renewable soy protein based resins and high strength liquid crystalline cellulose fibers. For comparison, E-glass and aramid ($Kevlar^{(R)}$) fiber reinforced composites were also prepared using the same modified soy protein resins. The modification of soy protein included forming an interpenetrating network-like (IPN-like) resin with mechanical properties comparable to commonly used epoxy resins. The IPN-like soy protein based resin was further reinforced using nano-clay and microfibrillated cellulose. Fiber/resin interfacial shear strength was characterized using microbond method. Tensile and flexural properties of the composites were characterized as per ASTM standards. A comparison of the tensile and flexural properties of the high strength composites made using the three fibers is presented. The results suggest that these green composites have excellent mechanical properties and can be considered for use in primary structural applications. Although significant additional research is needed in this area, it is clear that advanced green composites will some day replace today's advanced composites made using petroleum based fibers and resins. At the end of their life, the fully sustainable 'advanced green composites' can be easily disposed of or composted without harming the environment, in fact, helping it.

• Geomechanics and Engineering
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• 제32권6호
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• pp.601-613
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• 2023

Low liquid limit silt, widely distributed in the middle and down reaches of Yellow River, has the disadvantages of poor grading, less clay content and poor colloidal activity. It is very easy to cause vehicle jumping at the bridge-embankment transition section when the low liquid limit silt used as the backfill at the abutment back. In this paper, a series of laboratory tests were carried out to study the physical and mechanical properties of the low liquid limit silt used as back filling. Ground granulated blast furnace slag (GGBFS) was excited by active MgO and hydrated lime to solidify silt as abutment backfill. The optimum ratio of firming agent and the compaction and mechanical properties of reinforced soil were revealed through compaction test and unconfined compressive strength (UCS) test. Scanning electron microscope (SEM) test was used to study the pore characteristics and hydration products of reinforced soil. 6% hydrated lime and alkali activated slag were used to solidify silt and fill the model of subgrade respectively. The pavement settlement regulation and soil internal stress-strain regulation of subgrade with different materials under uniformly distributed load were studied by model experiment. The effect of alkali activated slag curing agent on curing silt was verified. The research results can provide technical support for highway construction in silt area of the Yellow River alluvial plain.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.175-176
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• 2023

The masonry structure is constructed by cement mortar binding material of brick objects and uses reinforced hardware(connected hardware or wall tie) together when building. However, over time, the corrosion of reinforced steel and the deterioration of joint mortar as well as bricks cause the risk of collapse. In particular, when the externally decorated brick wall is installed on the concrete girder for each floor, the angle bracket is not constructed or corroded, the full-layer weight load is applied to the wall of 0.5B, which is an example of full-scale or collapse. As a result of the evaluation, it was confirmed that the performance was improved compared to the existing bracket, and we plan to carry out a real-life test and long-term performance review of the building using the bracket in the future.

• 한국건축시공학회지
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• 제1권1호
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• pp.160-168
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• 2001

This study aims at the development of computer program for the deformation analysis of soft ground, and using this computer program, study the constraint effect of deformation heaving, lateral displacement of the soft ground reinforced with improvement of soft ground up to hard strata, under intact state(natural). The following results are obtained. 1. Improvement of soft ground to the hard strata works well against the settlement of neighboring ground. 2. the larger the rigidity or width of improvement of layer to hard strata is, the less settlement occurs. 3. Improvement of soft ground to the hard strata is of no use.

• Structural Engineering and Mechanics
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• 제22권4호
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• pp.449-467
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• 2006

Most existing concrete structures in Taiwan are considered nonductile due to insufficient transverse reinforcement and poor detailing of frame elements. Such features are fairly typical for buildings constructed prior to 1997, at which time the local building code was revised based on ACI 318-95. Among these structures, many contain perimeter or partition walls made of concrete or clay brick for architectural purposes. These walls, though treated as non-structural components in common design practice, could affect the structural behavior of the buildings during an earthquake. To study the behavior of such structures under seismic load, experiments were conducted on concrete frames of various configurations to show the force-deformation relationships, damage patterns, and other characteristics of the frames. For further interest, similar units with columns jacketed by carbon-fiber-reinforced-polymer (CFRP) were also tested to illustrate the effectiveness of this technique in the retrofit of concrete frames.

• Structural Engineering and Mechanics
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• 제74권1호
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• pp.121-128
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• 2020

This paper presents an experimental study on the dynamic characteristics of infilled reinforced concrete (RC) frames. A 1/3-scaled, one-bay, three-storey RC frame was produced and tested by using operational modal analysis (OMA). The experiments were performed on five specimens: one reference frame with no infill walls and four frames with infill walls. The RC frame systems included infill walls made of hollow clay brick, which were constructed in four different patterns. The dynamic characteristics of the patterns, including the frequency, mode shapes and damping ratios in the in-plane direction, were obtained by 6 accelerometers. Twenty-minute records under ambient vibration were collected for each model, and the dynamic characteristics were determined using the ambient vibration testing and modal identification software (ARTeMIS). The experimental studies showed that the infill walls significantly affected the frequency value, rigidity and damping ratio of the RC frame system.

• Geomechanics and Engineering
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• 제38권3호
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• pp.231-247
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• 2024

The use of lime stabilization and geosynthetic reinforcement is a common approach to improve the performance of fine-grained soils in geotechnical applications. However, the impact of this combination on the soil-geosynthetic interaction remains unclear. This study addresses this gap by evaluating the interface efficiency and soil-geosynthetic interaction parameters of lime-stabilized clay (2%, 4%, 6%, and 8% lime content) reinforced with geotextile or geogrid using direct shear tests at various curing times (1, 7, 14, and 28 days). Additionally, machine learning algorithms (Support Vector Machine and Artificial Neural Network) were employed to predict soil shear strength. Findings revealed that lime stabilization significantly increased soil shear strength and interaction parameters, particularly at the optimal lime content (4%). Notably, stabilization improved the performance of soil-geogrid interfaces but had an adverse effect on soil-geotextile interfaces. Furthermore, machine learning algorithms effectively predicted soil shear strength, with sensitivity analysis highlighting lime percentage and geosynthetic type as the most significant influencing factors.

• 대한토목학회논문집
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• 제34권3호
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• pp.907-917
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• 2014

연약지반을 매립후 굴착을 시행할 경우 흙막이벽체를 설치하더라도 배면지반에 지반파괴가 발생한다. 이를 최소화하기 위해 억지말뚝을 적용 후 실내모형 실험을 시행하여 억지효과를 규명하였다. 모형토조내 점토를 충진하고 계측시스템을 이용하여, 무보강일 경우와 억지말뚝으로 보강한 경우를 설정하여 굴착에 따른 배면지반의 침하, 간극수압, 토압을 측정하였다. 모형실험 결과 억지말뚝으로 보강할 경우 무보강시와 비교할 때 굴착 단계의 증가와 배면지반의 침하가 감소된 것으로 평가되었다. 간극수압은 보강여부와는 크게 상관없었고, 침하율은 적게 나타났다. 또한, 굴착깊이가 배면지반에 매우 큰 영향을 미치고, 굴착지점과 가까울수록 최대 침하가 발생되는 것으로 평가되었다.