This study performed the seismic response analysis of an LNG storage tank supported by a disconnected piled raft foundation (DPRF) with a load transfer platform (LTP). For this purpose, a precise analytical model with simultaneous consideration of Fluid-Structure Interaction (FSI) and Soil-Structure Interaction (SSI) was used. The effect of the LTP characteristics (thickness, stiffness) of the DPRF system on the seismic response of the superstructure (inner and outer tanks) and piles was analyzed. The analytical results were compared with the response of the piled raft foundation (PRF) system. The following conclusions can be drawn from the numerical results: (1) The DPRF system has a smaller bending moment and axial force at the head of the pile than the PRF system, even if the thickness and stiffness of the LTP change; (2) The DPRF system has a slight stiffness of the LTP and the superstructure member force can increase with increasing thickness. This is because as the stiffness of the LTP decreases and the thickness increases, the natural frequency of the LTP becomes closer to the natural frequency of the superstructure, which may affect the response of the superstructure. Therefore, when applying the DPRF system, it is recommended that the sensitivity analysis of the seismic response to the thickness and stiffness of the LTP must be performed.

This study monitored temperature using electronic sensors and developed a prediction model for compost maturity. The experiment used swine manure in a mechanical composting facility equipped with a screw-type agitator, and the composting process was conducted for 60 d during the summer season in South Korea. Four electronic temperature sensors were installed on the inner wall between the compost piles on Days 7, 14, 21, and 28 for daily temperature monitoring. Compost samples were collected daily for 60 d, and compost maturity was analyzed using the Solvita method. Multiple comparisons, correlations, and modeling were performed using the stat package in R software. The average compost pile temperatures was 39.1±3.9, 36.4±4.3, 31.3±4.5, and 35.4±8.1 on days 7, 14, 21, and 28, respectively, after composting. The average compost maturity according to the composting date was 3.61±0.60, 4.13±0.59, 4.26±0.47, and 4.32 ±0.56 on days 7, 14, 21, and 28, respectively. A significant negative correlation was observed between the compost composting periods (seven, 14, 21, and 28 d) and the temperature of all compost piles (p<0.05), where the correlation coefficients were -0.329, -0.382, -0.507, and -0.634, respectively. A significant positive correlation was observed between the compost composting periods (seven, 14, 21, and 28 d) and the maturity of the compost (p<0.05), where the correlation coefficients were 0.410, 0.550, 0.727, and 0.840, respectively. The model for predicting the maturation of the 14 d average compost pile according to the compost composting period and the average temperature for 14 d was y=0.026 x d – 0.021 x mt.x_14 d (mean temperature for 14 d) + 4.336 (R2=0.7612, p<0.001). This study can be considered a basic reference for predicting compost maturity by the proposed model using electronic temperature sensors.

농가에서 수거한 돈분뇨 고형물을 원료로 하여 퇴비단에 공기를 공급하는 송풍방법을 4 가지(T1, T2, T3, T4)로 구분하여 33일 동안 퇴비화 실험을 수행한 결과를 종합적으로 분석 한 결론은 다음과 같다. 1. 처리형태별 각 퇴비단의 온도변화를 측정한 결과, 송풍을 실시한 퇴비단 T1의 온도는 퇴비화 개시 직후부터 급격하게 상승하여 퇴비화 1일 이내에 65oC까지 상승하는 결과를 보였다. 또한 송풍 처리구간의 온도변화 곡선을 보면 공기 배출통 로를 설치한 처리구 T3, T4가 단순 송풍구 T2에 비해 퇴비단의 온도가 더 높게 나타났다. 2. 퇴비단의 pH는 전체 처리구 모두에서 퇴비화 초기 단계에서는 pH 수준이 약간 낮아지다가 퇴비화 기간이 경과함에 따라 다시 상승하는 추세를 보였다. 3. 실험기간이 경과함에 따라 각 처리구별 퇴비의 수분함량은 점차적으로 감소하는 경향을 보였다. 수분 감소 정도는 T1, T2, T3, T4 모두 다 비슷한 수준을 나타냈다. 4. 퇴비중의 VS 함량은 전체 처리구 모두에서 퇴비화 기간이 경과함에 따라 감소하는 경향을 보였다. VS 감소 정도는 T1과 T2에 비해 T3와 T4에서 상대적으로 더 높은 비율로 나타났으며 T1과 T2는 비슷한 경향을 나타냈다. 5. 퇴비화기간이 경과함에 따라 EC의 변화는 크게 나타나지는 않았으나 T4에서는 약간 감소하는 경향을 나타냈다. 6. 송풍조건에 따른 각 처리구별 종자발아 지수는 T2와 T3에 서 양호하게 나타났으며 T1과 T4는 상대적으로 더 낮게 나타 났다. 7. 송풍조건에 따른 각 처리구별 부숙도는 전체 처리구 모두에서 퇴비화 개시 후 9일 이후부터는 부숙이 완료된 것으로 나타났다. 부숙도는 T2와 T3에서 양호하게 나타났으며 T1과 T4는 상대적으로 더 늦게 부숙 상태에 도달하는 것으로 나타났으며 종자 발아지수를 기준으로 할 때는 T2와 T3 처리구가 양호한 결과를 보였다.

Earthquake preparedness has become more important with recent increase in the number of earthquakes in Korea, but many existing structures are not prepared for earthquakes. There are various types of liquefaction prevention method that can be applied, such as compaction, replacement, dewatering, and inhibition of shear strain. However, most of the liquefaction prevention methods are applied before construction, and it is important to find optimal methods that can be applied to existing structures and that have few effects on the environment, such as noise, vibration, and changes in underground water level. The purpose of this study is to estimate the correlation between the displacement of a structure and variations of pore water pressure on the ground in accordance with the depth of the sheet file when liquidation occurs. To achieve this, a shaking table test was performed for Joo-Mun-Jin standard sand and an earth pressure, accelerometer, pore water pressure transducer, and LVDT were installed in both the non-liquefiable layer and the liquefiable layer to measure the subsidence and excess pore water pressure in accordance with the time of each embedded depth. Then the results were analyzed. A comparison of the pore water pressure in accordance with Hsp/Hsl was shown to prevent lateral water flow at 1, 0.85 and confirmed that the pore water pressure increased. In addition, the relationship between Hsp/Hsl and subsidence was expressed as a trend line to calculate the expected settlement rate formula for the embedded depth ratio.

연약지반이 두껍고 다양한 지층으로 구성된 지역에 건설되는 단일형 현장타설말뚝 교량은 다양한 지층을 통해서 단일형 말뚝으로 입력되는 지반운동에 대해서 내진안전성을 확보하는 것이 중요하다. 본 연구에서는 설계지반운동에 부합되는 다수의 인공합성지진을 생성하여 이를 암반의 입력지반으로 하여 지반해석을 수행하여 각 지층에서의 지반가속도이력을 산정하였다. 이 가속도이력을 이용하여 각 지층의 지반을 등가스프링으로 모델화하고, 각 지층에서의 가속도시간이력을 입력지반 운동으로 하는 다지점 가진 지진해석을 수행하였다. 연약층의 비선형거동특성으로 입력지반운동의 세기는 크게 증폭되지 않아서 교량은 탄성영역 내에서 거동하였다. 한편, 특정 지층에서 산정된 가속도이력을 모든 지반스프링에 동시에 입력하면 응 답이 감소하였다. 따라서, 다지점가진 해석을 수행하지 않으면 이러한 형식의 교량의 내진성능을 과대평가할 수 있다.

Recent changes in the construction method of piles to minimize noise, along with the development of high-strength reinforcement, have provided an economical high performance RC pile development to compensate for the disadvantages of existing PHC piles. In this study, a methodology for the development of cross - section details of high performance RC piles of various performances is presented by freely applying high strength steel and concrete. This study suggested a technique for calculating bending moments for a given axial force corresponding to the allowable crack widths and this can be used for serviceablity check. In calculating the design shear force, the existing design equation applicable to the rectangular or the I section was modified to be applicable to the hollow circular section. In particular, in the limit state design method, the shear force is calculated in proportion to the axial force, and the procedure for calculating PV diagram is established. Last, the section details are determined through PM diagrams that they have the similar flexural and axial-flexural performances of the PHC pile A, B and C types with a diameter of 500 mm. To facilitate the application of the selected standard sections to the practical tasks, the design PM diagram and design shear forces are proposed in accordance with the strength design method and limit state design method.

As a method of seismic-design for pile-supported wharves, equivalent static analysis, response spectrum analysis, and time history analysis method are applied. Among them, the response spectrum analysis is widely used to obtain the maximum response of a structure. Because the ground is not modeled in the response spectrum analysis of pile-supported wharves, the amplified input ground acceleration should be calculated by ground classification or seismic response analysis. However, it is difficult to calculate the input ground acceleration through ground classification because the pile-supported wharf is build on inclined ground, the methods to calculate the input ground acceleration proposed in the standards are different. Therefore, in this study, the dynamic centrifuge model tests and the response spectrum analysis were carried out to calculate the appropriate input ground acceleration. The pile moment in response spectrum analysis and the dynamic centrifuge model tests were compared. As a result of comparison, it was shown that the response spectrum analysis results using the amplified acceleration in the ground surface were appropriate.

본 연구는 소비자의 선호 촉감을 고려한 세면용 타월 개발에 도움을 주고자 수행되었다. 타월의 바탕조직은 동일하지만(면섬유), 파일을 구성하는 섬유의 종류가 서로 다른 3종(면 100%, 면 50% / 대나무 50%, 대나무 100%)을 시료로 선정하였다. 타월을 표준 세탁조건으로 반복세탁을 실시하였으며, 10회 세탁한 타월에 대하여 섬유유연제를 처리하여, 세탁에 따른 유연성과 흡수성(흡수속도와 흡수율) 등의 성능 변화를 고찰하고 대학생 남녀 소비자를 대상으로 주관적 감각과 촉감 선호도를 평가시켰다. 세탁횟수와 파일섬유의 종류에 따라 타월의 유연성은 유의한 차이를 보이지 않았다. 타월의 흡수성은 세탁에 따른 파일섬유의 종류에 따라 유의한 차이를 보여, 흡수속도는 대나무섬유 100%로 된 타월에서 높았으나, 흡수율은 면섬유로 된 타월이 높았다. 세탁 전 타월의 파일섬유 종류에 따른 주관적 감각 평가는 유의한 차이가 없었다. 세탁이 반복될수록 파일섬유의 종류에 따른 주관적 감각은 유의한 차이를 보였으며, 섬유유연제 처리시 더 부드럽고 매끄러우며 촉촉해진다고 평가하였다. 세탁 전 타월에 대한 촉감 선호도는 선호하는 편이었으나, 파일섬유 종류에 따른 유의한 차이는 없었다. 세탁횟수가 증가함에 따라 타월에 대한 촉감 선호도는 다소 저하되었으며, 대나무섬유로 된 타월의 촉감을 가장 선호하였다. 타월의 촉감 선호도에는 평활감, 유연감 등의 주관적 감각과 섬유유연제 처리가 영향을 주었다

When piles adjacent to deep excavations (i.e. tunnel operation), pile for slope stabilization, highway embankments near abutment piles in soft soil, the load generates lateral soil movement on pile. The lateral soil movement leads to develop the horizontal pressure between the pile and soil, also increase deflection as well as bending moment in the pile. In order to investigate a single pile subjected to horizontal loads due to the movement of the upper soil layer, the pile and soils are modelled by using 3D finite element analysis in this paper. The finite element analysis software used in this study is ANSYS. Furthermore, the soil's elastic behaviour follows the Mohr-Coulomb model and the pair of contact elements is used to simulate the pile-soil contact. A good correlation between laboratory and predicted results is observed in the validation analysis. The parametric study also demonstrates that soil Young's modulus and soil movement profile are key factors in predicting the behaviour of the pile.

Dynamic numerical simulation of pile-supported slab track system embedded in a soft soil and embankment was performed. 3D model was formulated in a time domain to consider the non-linearity of soil by utilizing FLAC 3D, which is a finite difference method program. Soil non-linearity was simulated by adopting the hysteric damping model and liner elements, which could consider soil-pile interface. The long period seismic loads, Hachinohe type strong motions, were applied for estimating seismic respose of the system, Parametric study was carried out by changing subsoil layer profile, embankment height and seismic loading conditions. The most of horizontal permanent displacement was initiated by slope failure. Increase of the embedded height and thickness of the soft soil layer leads increase of member forces of PHC piles; bending moment, and axial force. Finally, basic guidelines for designing pile-supported slab track system under seismic loading are recommended based on the analysis results.

In case of underground construction affected by groundwater, CIP (Cast-In-Place Pile) method is generally used to resolve the geo-hydraulic problem. However, as this method has poor connectivity between piles, an auxiliary method for cut-off is needed in many cases. In this study, a new concept earth retaining wall method (H-CIP) with no auxiliary method, by using surfactant grout (Hi-FA) which improves antiwashout and infiltration ability, is introduced, and its field applicability is evaluated. CIP and H-CIP piles were installed with same ground conditions, and field permeability tests were conducted to verify the performance. As results, newly contrived H-CIP method shows higher antiwashout performance for cut-off than conventional CIP method.

Conventional steel and concrete piles are widely applied in civil engineering industries with long time experience and many advantages. However, steel pipe piles, a sort of most common steel pile, are prone to losing their structural integrity over time due to corrosive and humid conditions. Moreover, concrete piles such as in-situ concrete piles and pretensioned spun high strength concrete (PHC) piles are subject to deterioration of their long-term structural durability. Therefore, Hybrid FRP-concrete composite pile (HCFFT) was developed. HCFFT is consisted of pultruded FRP (PFRP) unit module, filament winding FRP which is in the outside of mandrel composed of circular shaped assembly of PFRP unit modules, and concrete which is casted inside of the circular tube shaped hybrid FRP pile. Therefore, PFRP can increase the flexural load carrying capacity, while filament winding FRP and concrete filled inside can increase axial load carrying capacity. In this paper, field loading experiments were conducted to evaluate field bearing capacity of HCFFT pile with connection and HCFFT pile without connection.

Recently, for efficiency increase of the wind turbine tower, turbine has been enlarged and installation location has been transferring to offshore. The importance of the support structure is emphasized when a wind turbine tower is installed on offshore. The support structure is influenced not only by the system operating loads but also by various marine condition loads. Accurate and safe design is essential because the connection between the support structure and the wind tower can be relatively fragile. In particular, the type of foundation pile and sleeve grout connection were adapted from DNV, API, and ISO that are typically used for wind towers, and they have been continuously studied by many researchers. However, the experimental results by researchers are different from the design equations, and it needs to modify the formula according to connection properties and material. Therefore, this study investigates the design equation presented in existing design criteria and the results of research conducted by existing researchers, and analyzes ultimate strength and failure modes.

Seismic analyses of a pile under a large rigid basement foundation embedded in the homogeneous soil layer were performed practically by a response displacement method assuming a sinusoidal wave form. However, it is hard to take into account the characteristics of a large mat foundation and a heterogeneous soil layer with the response displacement method. The response displacement method is relevant to the 2D problems for longitudinal structures such as tunnel, underground cave structure, etc., but might not be relevant with isolated foundations for building structures. In this study, seismic pile analysis by a pseudo 3D finite element method was carried out to compare numerical results with results of the response displacement method considering 3D characteristics of a foundation-soil system which is important for the building foundation analyses. Study results show that seismic analyses results of a response displacement method are similar to those of a pseudo 3D numerical method for stiff and dense soil layers, but they are too conservative for a soft soil layer inducing large soil pressures on the foundation wall and large pile displacements due to ignored foundation rigidity and resistance.

Two types of connection between the abutment and CFT pile were proposed for the sub-structure of the integral abutment bridge. One was a bolt connection (Type-A) and the other was a hook connection (Type-B). To analyze the performance of connection Type-A and Type-B, a quasi-static experiment was carried out. According to experimental results, the destruction occurred at the connection point and so both type A and type B need to have a reinforced design as the link between the abutment and CFT pile. However, when the load resistance performance and energy dissipation capacity was analyzed, the performance of connection Type-B was superior to the performance of connection Type-A.

최근 신재생 에너지 중 하나인 풍력발전에 대한 관심이 증가하고 있다. 풍력발전은 토지구입비, 소음문제에 자유로운 해상풍력으로 추세가 옮겨가고 있으며 이를 위한 연구개발이 전 세계적으로 활발히 이루어지고 있다. 그러나 해상에 위치한 풍력발전을 위한 설계기준은 국내, 국외 모두 없는 실정이다. 이 점을 고려하여 국내, 국외의 구조설계기준인 도로교 설계기준, 항만 및 어항 설계기준, DNV OS를 참고하여 다중 파일기초 콘크리트 지지구조물(MCF)의 내진해석을 수행하여 결과를 비교하였다. 또한 시간에 의한 효과를 확인하기 위하여 시간이력 해석 또한 수행되었다. 부가질량법(Added-mass method)을 사용하여 물과 구조의 상호작용을 고려하였고 물의 유무에 따라 구조물의 반응을 비교하였다.

In this study, a quasi-static experiment was conducted on the connection performance between the integral abutment bridge and CFT pile. Six experiment specimen were manufactured and were divided into type A and type B. Experiment specimens of Type A were connected with bolts and experiment specimens of Type B were connected with hooks. In the experiment results the connection performance of Type B showed excellent performance more than that of Type A.