• Title/Summary/Keyword: Behavior prediction

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Method of Estimating Pile Load-displacement Curve Using Bi-directional Load Test (양방향 재하시험을 이용한 말뚝의 하중-변위곡선 추정방법)

  • Kwon Oh-Sung;Choi Yong-Kyu;Kwon Oh-Kyun;Kim Myoung-Mo
    • Journal of the Korean Geotechnical Society
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    • v.22 no.4
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    • pp.11-19
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    • 2006
  • For the last decade, the hi-directional testing method has been advantageous over the conventional pile load testing method in many aspects. However, because the hi-directional test uses a loading mechanism entirely different from that of the conventional pile load testing method, many investigators and practicing engineers have been concerned that the hi-directional test would give inaccurate results, especially about the pile head settlement behavior. Therefore, a hi-directional load test and the conventional top-down load test were executed on 1.5 m diameter cast-in-situ concrete piles at the same time and site. Strain gauges were placed on the piles. The two tests gave similar load transfer curves at various depth of piles. However, the top-down equivalent curve constructed from the hi-directional load test results predicted the pile head settlement under the pile design load to be about one half of that predicted by the conventional top-down load test. To improve the prediction accuracy of the top-down equivalent curve, a simple method that accounts for the pile compression is proposed. It was also shown that the strain gauge measurement data from the hi-directional load test could reproduce almost the same top-down curve.

Prediction of the Natural Frequency of Pile Foundation System in Sand during Earthquake (사질토 지반에 놓인 지진하중을 받는 말뚝 기초 시스템의 고유 진동수 예측)

  • Yang, Eui-Kyu;Kwon, Sun-Yong;Choi, Jung-In;Kim, Myoung-Mo
    • Journal of the Korean Geotechnical Society
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    • v.26 no.1
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    • pp.45-54
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    • 2010
  • It is important to calculate the natural frequency of a piled structure in the design stage in order to prevent resonance-induced damage to the pile foundation and analyze the dynamic behavior of the piled structure during an earthquake. In this paper, a simple but relatively accurate method employing a mass-spring model is presented for the evaluation of the natural frequency of a pile-soil system. Greatly influencing the calculation of the natural frequency of a piled structure, the spring stiffness between a pile and soil was evaluated by using the coefficient of subgrade reaction, the p-y curve, and the subsoil elastic modulus. The resulting natural frequencies were compared with those of 1-g shaking table tests. The comparison showed that the natural frequency of the pile-soil system could be most accurately calculated by constructing a stiffness matrix with the spring stiffness of the Reese (1974) method, which utilizes the coefficient of the subgrade reaction modulus, and Yang's (2009) dynamic p-y backbone curve method. The calculated natural frequencies were within 5% error compared with those of the shaking table tests for the pile system in dry dense sand deposits and 5% to 40% error for the pile system in saturated sand deposits depending on the occurrence of excess pore water pressure in the soil.

Development of Integrated Management System Based on GIS on Soft Ground (GIS 기법을 이용한 연약 지반 시공 관리 시스템의 개발)

  • Chun, Sung-Ho;Woo, Sang-Inn;Chung, Choong-Ki;Choi, In-Gul
    • Journal of the Korean Geotechnical Society
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    • v.23 no.7
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    • pp.37-46
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    • 2007
  • In the practice of preloading method for soft ground improvement, field engineers need information of ground properties, construction works and field monitoring on ground behaviors of the site. So, integrating all these informations into one database can provide more efficient way for managing and utilizing the data for construction management. In this study, integrated system for construction management of ground improvement sites under preloading is developed. The developed system consists of database (DB) and application program. The database contains all collected data in a construction site and processed data in the system with their geographic information. All informations in the database are standardized from the result of data characterization. Application program performs various functions on managing and utilizing information in the database; pre- and post- data processing with graphic visualization of output, spatial data interpolation, and prediction of ground behavior using field measuring data. And by providing integrating informations and predictions over entire project area with comprehensible visual displays, the applicability and effectiveness of the developed system for construction management were confirmed.

Homogenization of Plastic Behavior of Metallic Particle/Epoxy Composite Adhesive for Cold Spray Deposition (저온 분사 공정을 위한 금속입자/에폭시 복합재료 접착제의 소성 거동의 균질화 기법 연구)

  • Yong-Jun Cho;Jae-An Jeon;Kinal Kim;Po-Lun Feng;Steven Nutt;Sang-Eui Lee
    • Composites Research
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    • v.36 no.3
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    • pp.199-204
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    • 2023
  • A combination of a metallic mesh and an adhesive layer of metallic particle/epoxy composite was introduced as an intermediate layer to enhance the adhesion between cold-sprayed particles and fiber-reinforced composites (FRCs). Aluminum was considered for both the metallic particles in the adhesive and the metallic mesh. To predict the mechanical characteristics of the intermediate bond layer under a high strain rate, the properties of the adhesive layer needed to be calculated or measured. Therefore, in this study, the Al particle/epoxy adhesive was homogenized by using a rule of mixture. To verify the homogenization, the penetration depth, and the thickness decrease after the cold spray deposition from the undeformed surface, was monitored with FE analysis and compared with experimental observation. The comparison displayed that the penetration depth was comparable to the diameters of one cold spray particle, and thus the homogenization approach can be reasonable for the prediction of the stress level of particulate polymer composite interlayer under a high strain rate for cold spray processing.

A Constitutive Model for Rotation of Principal Stress Axes during Direct Simple Shear Deformation (직접단순전단변형에 따른 주응력 방향의 회전을 고려한 구성모델)

  • Park, Sung-Sik;Lee, Jong-Cheon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1C
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    • pp.53-62
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    • 2008
  • A constitutive model, which can simulate the effect of principal stress rotation associated with direct simple shear test, is proposed in this study. The model is based on two mobilized planes. The plastic strains occur from the two mobilized planes, and depend on stress state, and they are added. The first plane is a plane of maximum shear stress, which rotates about the horizontal axis, and the second plane is a horizontal plane which is spatially fixed. The second plane is used to consider the effect of principal stress rotation on simple shear tests under different stress states. The soil skeleton behavior observed in drained simple shear tests is captured in the model. This constitutive model is incorporated into the dynamic coupled stress-flow finite difference program FLAC. The model is first calibrated with drained simple shear tests on loose Fraser River sand. The measured shear stress and volume change are partially induced by principal stress rotation and compared with model calculations. The model is verified by comparing predicted and measured settlements due to rigid footing resting on loose sands. Settlements predicted by the proposed model were very similar to measured settlements. Mohr-Coulomb model can not consider the effect of principal stress rotation and its prediction was only 20% of measured settlements.

Prediction of the Static Deflection Profiles on Suspension Bridge by Using FBG Strain Sensors (FBG 변형률센서를 이용한 현수교의 정적 처짐형상 추정)

  • Cho, Nam-So;Kim, Nam-Sik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.5A
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    • pp.699-707
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    • 2008
  • For most structural evaluation of bridge integrity, it is very important to measure the geometric profile, which is a major factor representing the global behavior of civil structures, especially bridges. In the past, because of the lack of appropriate methods to measure the deflection profile of bridges on site, the measurement of deflection has been restricted to just a few discrete points along the bridge, and the measuring points have been limited to the locations installed with displacement transducers. Thus, some methods for predicting the static deflection by using fiber optic strain sensors has been applied to simply supported bridges. In this study, a method of estimating the static deflection profile by using strains measured from suspension bridges was proposed. Based on the classical deflection theory of suspension bridges, an equation of deflection profile was derived and applied to obtain the actual deflection profile on Namhae suspension bridge. Field load tests were carried out to measure strains from FBG strain sensors attached inside the stiffening girder of the bridge. The predicted deflection profiles were compared with both precise surveying data and numerical analysis results. Thus, it is found that the equation of predicting the deflection profiles proposed in this study could be applicable to suspension bridges and the FBG strain sensors could be reliable on acquiring the strain data from bridges on site.

Neural Network-Based Prediction of Dynamic Properties (인공신경망을 활용한 동적 물성치 산정 연구)

  • Min, Dae-Hong;Kim, YoungSeok;Kim, Sewon;Choi, Hyun-Jun;Yoon, Hyung-Koo
    • Journal of the Korean Geotechnical Society
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    • v.39 no.12
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    • pp.37-46
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    • 2023
  • Dynamic soil properties are essential factors for predicting the detailed behavior of the ground. However, there are limitations to gathering soil samples and performing additional experiments. In this study, we used an artificial neural network (ANN) to predict dynamic soil properties based on static soil properties. The selected static soil properties were soil cohesion, internal friction angle, porosity, specific gravity, and uniaxial compressive strength, whereas the compressional and shear wave velocities were determined for the dynamic soil properties. The Levenberg-Marquardt and Bayesian regularization methods were used to enhance the reliability of the ANN results, and the reliability associated with each optimization method was compared. The accuracy of the ANN model was represented by the coefficient of determination, which was greater than 0.9 in the training and testing phases, indicating that the proposed ANN model exhibits high reliability. Further, the reliability of the output values was verified with new input data, and the results showed high accuracy.

A Study on Back Analysis Settlement Prediction of Soft Ground Using Numerical Analysis and Measurement Data (수치해석과 계측데이터를 이용한 연약지반의 역해석 침하 예측에 관한 연구)

  • Sangju Jeon;Hyeok Seo;Daehyeon Kim
    • Journal of the Korean Geosynthetics Society
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    • v.23 no.2
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    • pp.9-17
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    • 2024
  • When constructing on soft ground, managing ground settlement and safety is crucial. However, there often exists a significant disparity between the actual behavior of the ground and the design plans. In this study, we aimed to compare and analyze the difference between the predicted settlement based on theoretical formulas and the measured settlement during construction, in order to predict settlement. For this purpose, we analyzed settlement data from 18 construction sites. The results indicated that the back analysis settlement values were similar to the measured settlement values, whereas the design settlement values were significantly higher compared to the measured settlement values. Specifically, the design settlement values were 1.2 to 1.4 times higher than those derived from back analysis using measured values. The RMSE analysis revealed a value of 0.6212m for the design settlement and 0.1697m for the back analysis settlement. The difference between the back analysis settlement and the measured settlement was more than 70% lower than the difference between the design settlement and the measured settlement. This indicates that the back analysis settlement values exhibit lower error rates compared to the design settlement values.

A Comparative Study of Symptoms in Patients with Hwabyung according to Yin-Yang Personality Types (음양 성격 유형에 따른 화병 환자의 증상 비교 연구)

  • Seok-In Yoon;Han Chae;Hui-Yeong Park;Hyun Woo Lee;Chan Park;Sun-Yong Chung;Jong Woo Kim
    • Journal of Oriental Neuropsychiatry
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    • v.35 no.2
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    • pp.141-151
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    • 2024
  • Objectives: To compare symptoms and characteristics among patients diagnosed with Hwabyung according to their yin-yang personality types. Methods: A structured clinical interview was conducted to diagnose Hwabyung, followed by a cross-sectional study involving a total of 118 Hwabyung patients (95 females). Various measures including the Sasang Personality Questionnaire (SPQ), Hwabyung Comprehensive Test (HCT), HwaByung Scale (HBS), State-Trait Anger Expression Inventory (STAXI), Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI), Eogul Scale (ES), and Patient Health Questionnaire-15 (PHQ-15) were administered. Results: SPQ-total showed significant negative correlations with HBS-personality and STAXI-control, and a significant positive correlation with STAXI-out. SPQ-behavior showed significant positive correlations with HBS-symptom, STAXI-trait, STAXI-in, STAXI-out, BDI-II, BAI, ES, and PHQ-15. SPQ-cognition exhibited significant negative correlations with HBS-personality, STAXI-control, and ES. SPQ-emotion had significant negative correlations with HBS-personality and STAXI-in and a significant positive correlation with STAXI-out. SPQ-Yin demonstrated a significantly higher HBS-personality than SPQ-Yang. SPQ-Yang exhibited significantly higher STAXI-out than SPQ-Yin, whereas SPQ-Yin showed significantly higher STAXI-control and STAXI-in than SPQ-Yang. Although differences in depression, anxiety, resentment, and physical symptoms between yin and yang were not statistically significant, variations in interpretation criteria were observed. Conclusions: Anger expression patterns and physical/psychological symptoms among Hwabyung patients are different based on their yin-yang personality types. These findings can inform the prediction of symptoms in Hwabyung patients according to their yin-yang personality types and aid in establishing appropriate treatment plans.

Predictive Factors of Health promotion behaviors of Industrial Shift Workers (산업장 교대근무 근로자의 건강증진행위 예측요인)

  • Kim, Young-Mi
    • Korean Journal of Occupational Health Nursing
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    • v.11 no.1
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    • pp.13-30
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    • 2002
  • Industrial shift workers feels suffer mental stresses which are caused by unfamiliar day sleep, noisy environment, sleeping disorder by bright light, unusual contacts with family, difficulty in meeting with friends or having formal social meetings and other social limitations such as the use of transportation. Such stresses influence health of the workers negatively. Thus the health promotion policy for shift workers should be made considering the workers' ways of living and shift work specially. This study attempted to provide basic information for development of the health promotion program for industrial shift workers by examining predictive factors influencing health promotion behaviors of those workers. In designing the study, three power generation plants located in Pusan and south Kyungsang province were randomly selected and therefrom 280 workers at central control, boiler and turbine rooms and environmental chemistry parts whose processes require shift works were sampled as subjects of the study. Data were collected two times from September 17 to October 8, 1999 using questionnaires with helps of safety and health managers of the plants. The questionnaires were distributed through mails or direct visits. Means for the study included the measurement tool of health promotion behavior provided by Park(1995), the tool of self-efficacy measurement by Suh(1995), the tool of internal locus of control measurement by Oh(1987), the measurement tool of perceived health state by Park(1995) and the tool of social support measurement by Paek(1995). The collected data were analyzed using SPSS program. Controlling factors of the subjects were evaluated in terms of frequency and percentage ratio Perceived factors and health promotion behaviors of the subjects were done so in terms of mean and standard deviation, and average mark and standard deviation, respectively. Relations between controlling and perceived factors were analyzed using t-test and ANOVA and those between perceived factors and the performance of health promotion behaviors, using Pearson's Correlation Coefficient. The performance of health promotion behaviors was tested using t-test, ANOVA and post multi-comparison (Scheffe test). Predictive factors of health promotion behavior were examined through the Stepwise Multiple Regression Analysis. Results of the study are summarized as follows. 1. The performance of health promotion behaviors by the subjects was evaluated as having the value of mean, $161.27{\pm}26.73$ points(min.:60, max.:240) and average mark, $2.68{\pm}0.44$ points(min.:1, max.:4). When the performance was analyzed according to related aspects, it showed the highest level in harmonious relation with average mark, $3.15{\pm}.56$ points, followed by hygienic life($3.03{\pm}.55$), self-realization ($2.84{\pm}.55$), emotional support($2.73{\pm}.61$), regular meals($2.71{\pm}.76$), self-control($2.62{\pm}.63$), health diet($2.62{\pm}.56$), rest and sleep($2.60{\pm}.59$), exercise and activity($2.53{\pm}.57$), diet control($2.52{\pm}.56$) and special health management($2.06{\pm}.65$). 2. In relations between perceived factors of the subjects(self-efficacy, internal locus of control, perceived health state) and the performance of health promotion behaviors, the performance was found having significantly pure relations with self-efficacy (r=.524, P=.000), internal locus of control (r=.225, P=.000) and perceived health state(r=.244, P=.000). The higher each evaluated point of the three factors was, the higher the performance was in level. 3. When relations between the controlling factors(demography-based social, health-related, job-related and human relations characteristics) and the performance of health promotion behaviors were analyzed, the performance showed significant differences according to marital status (t=2.09, P= .03), religion(F=3.93, P= .00) and participation in religious activities (F=8.10, P= .00) out of demography-based characteristics, medical examination results (F=7.20, P= .00) and methods of the collection of health knowledge and information(F=3.41, P= .01) and methods of desired health education(F=3.41, P= .01) out of health-related characteristics, detrimental factors perception(F=4.49, P= .01) and job satisfaction(F=8.41, P= .00) out of job-related characteristics and social support(F=14.69, P= .00) out of human relations characteristics. 4. The factor which is a variable predicting best the performance of health promotion behaviors by the subjects was the self-efficacy accounting for 27.4% of the prediction, followed by participation in religious activities, social support, job satisfaction, received health state and internal locus of control in order all of which totally account for 41.0%. In conclusion, the predictive factor which most influence the performance of health promotion behaviors by shift workers was self-efficacy. To promote the sense, therefore, it is necessary to develop the nursing intervention program considering predictive factors as variables identified in this study. Further industrial nurses should play their roles actively to help shift workers increase their capability of self-management of health.

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