• Steel and Composite Structures
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• 제22권2호
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• pp.217-234
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• 2016

In order to investigate mechanical properties and load-bearing capacity of T-shaped Concrete-Filled Square Steel Tubular (TCFST) composite columns under eccentric axial load, three T-shaped composite columns were tested under eccentric compression. Experimental results show that failure mode of the columns under eccentric compression was bending buckling of the whole specimen, and mono column performs flexural buckling. Specimens behaved good ductility and load-bearing capacity. Nonlinear finite element analysis was also employed in this investigation. The failure mode, the load-displacement curve and the ultimate bearing capacity of the finite element analysis are in good agreement with the experimental ones. Based on eccentric compression test and parametric finite element analysis, the calculation formula for the equivalent slenderness ratio was proposed and the bearing capacity of TCFST composite columns under eccentric compression was calculated. Results of theoretical calculation, parametric finite element analysis and eccentric compression experiment accord well with each other, which indicates that the theoretical calculation method of the bearing capacity is advisable.

• 한국농공학회지
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• 제39권2호
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• pp.124-133
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• 1997

Pile load test is good for estimating pile bearing capacity, but using this method is limited by time and cost required. Dynamic and static method is more convenient and economical, but confidence of estimated value by dynamic and static method are lower than that of pile load test. After being compared pile bearing capacity data obtained from pile load test with those of other two methods, the results from this study were summarised as follows. For allowable bearing capacity values greater than 175t per pile, bearing capacity acquired from static method was higher than that acquired from pile load test, whereas bearing capacity acquired from pile load test was higher than that acquired from static method for values under 175 per pile. It was that variance of bearing capacity was large when bearing capacity obtained by dynamic method was higher than 250t. Also bearing capacity based on dynamic method was higher than that based on pile load test. Allowable bearing capacity get from dynamic method suggested that carefull precautions are necessary in application for allowable bearing capacity values higher than 2S0ton per pile.

• Steel and Composite Structures
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• 제20권3호
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• pp.599-621
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• 2016

In order to study the working mechanism of rectangular steel-concrete composite columns subjected to compression-bending load and further determine the seismic performance index, a bottom strengthened rectangular steel reinforced concrete (SRC) column with concealed steel plates and a bottom strengthened rectangular concrete filled steel tube (CFST) columns were proposed. Six column models with different configurations were tested under horizontal low cyclic loading. Based on the experiments, the load-bearing capacity, stiffness and degradation process, ductility, hysteretic energy dissipation capacity, and failure characteristics of the models were analyzed. The load-bearing capacity calculation formulas for a normal section and an oblique section of bottom strengthened rectangular steel-concrete composite columns were pesented and a finite element (FE) numerical simulation of the classical specimens was performed. The study shows that the load-bearing capacity, ductility, and seismic energy dissipation capacity of the bottom strengthened rectangular steel-concrete composite columns are significantly improved compared to the conventional rectangular steel-concrete composite columns and the results obtained from the calculation and the FE numerical simulation are in good agreement with those from the experiments. The rectangular steel-concrete composite column with bottom strengthened shows better seismic behavior and higher energy dissipation capacity under suitable constructional requirements and it can be applied to the structure design of high-rise buildings.

• Steel and Composite Structures
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• 제47권3호
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• pp.437-450
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• 2023

A half open cross section built-up column, namely cold-formed thin-walled steel built-up column with 12-limbsection (CTSBC-12) is put forward. To deeply reveal the mechanical behaviors of CTSBC-12 under axial compression and put forward its calculation formula of axial bearing capacity, based on the previous axial compression experimental research, the finite element analysis (FEA) is conducted on 9 CTSBC-12 specimens, and then the variable parameter analysis is carried out. The results show the FEA is in good agreement with the experimental research, the ultimate bearing capacity error is within 10%. When the slenderness ratio is more than 96.54, the ultimate bearing capacity of CTSBC-12 decreases rapidly, and the failure mode changes from local buckling to global buckling. With the local buckling failure mode unchanged, the ultimate bearing capacity decreases gradually as the ratio of web height to thickness increases. Three methods are used for calculating the ultimate bearing capacity, the direct strength method of AISI S100-2007 gives result of ultimate axial load which is closest to the test and FEA results. But for simplicity and practicality, a simplified axial bearing capacity formula is proposed, which has better calculation accuracy with the slenderness ratio changing from 30 to 100.

• 한국지반신소재학회논문집
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• 제22권1호
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• pp.39-51
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• 2023

매입말뚝의 지지력은 많은 연구자들에 의해 연구되었다. 하지만 하중분담률과 침하량에 대하여 설계 자료와 말뚝재하시험 지료를 비교한 연구는 미미하였다. 그래서 매입 개단 강관말뚝에 대하여 설계식 자료와 정재하시험 결과를 비교하였다. 압축재하시험에서는 선단지지하중과 주면마찰하중의 분담률이 각각 13%~40%, 60%~87%로 나타났고, 이때의 침하량은 2.2mm~4.7mm로 측정되었다. 현행 지지력 산정식에서는 선단지지력과 주면마찰력이 각각 54%~75%, 25%~46%를 분담하는 것으로 나타났고, 침하량은 19.8mm~23.6mm로 계산되었다. 현행지지력 산정식에서의 침하량은 시험에서의 침하량보다 321%~776% 만큼 크게 나타났으며, 평균적으로 445%만큼 크게 나타났다. 말뚝재하시험에서의 하중분담률을 이용하여 침하량을 산정하면, 시험 침하량보다 137%~525% 만큼 크게 나타났으며, 평균적으로 204% 만큼 크게 나타났다. 하중분담률의 적절한 평가는 말뚝 기초의 침하량 산정에 중요한 영향을 미치는 것으로 확인되었다.

• 지질공학
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• 제30권1호
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• pp.59-69
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• 2020

CPR 시험말뚝에 대해 인발재하시험을 실시하고, 하중-변위 곡선과 하중-침하량 곡선을 분석한 후 항복하중과 허용지지력을 산정하여 주면마찰력을 평가하였다. 하중-변위 곡선으로부터 분석된 CPR 시험말뚝의 결과에 의하면, CPR 시험말뚝의 직경이 큰 경우의 항복하중과 허용지지력이 작은 경우보다 약 1.4배 이상 크게 나타났다. 하중-침하량 곡선으로 부터 분석된 결과에 의하면, CPR 시험말뚝의 직경 D500의 허용지지력이 D400보다 약 1.2~2.1배 큰 것으로 나타났다. 하지만, Fuller 분석에 의해 산정된 허용지지력은 P-S 곡선과 log P - log S 곡선에 의해 산정된 허용지지력과 큰 차이를 보여, Fuller 분석에 의한 허용지지력 산정은 적절하지 않은 것으로 판단되었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.455-462
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• 2003

The current practice of estimating bearing capacity usually employs the conventional bearing capacity formula originally developed for strip footings under vertical central loading, In order account for the effect of footing shape and eccentricity and inclination of loads, correction factors are introduced in the formula, which are derived based on a number of small-scale model test observations. In this paper, comparison of several formulations of bearing capacity factors, as well as values of these factors, are presented. And the conventional bearing capacity equations are compared with some of other failure loci proposed for cohesive soil. Also, the bearing capacity of shallow foundation estimated by the conventional bearing capacity equations are compared with the experimental load test results.

• Steel and Composite Structures
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• 제28권2호
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• pp.167-177
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• 2018

In order to investigate mechanical properties in the core area of Square Hollow Section(SHS) column connection with external stiffening ring, four specimens were tested under the static tension load. The failure modes, load-displacement curves and strain distribution were analyzed to study the mechanical properties and the load transfer mechanism of the core area of connections. The connections behave good ductility and load-bearing capacity under the static tension load. Parametric analysis was also conducted, in which the thickness of steel tube, extended width and thickness of the stiffening ring were considered as the parameters to investigate the effects on mechanical properties of the connections. Based on the experimental results, an analytical method for the bearing capacity of connection with external stiffening ring under the static tension load was proposed. The theoretical results and the experimental results are in good agreement, which indicates that the theoretical calculation method of the bearing capacity is advisable.

• 한국안전학회지
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• 제18권1호
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• pp.81-88
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• 2003

Recently, pile foundations were constructed in rough or soft ground than ground of well condition thus it is important that prediction of ultimate bearing capacity and calculation of proper safety factor applied pile foundation design. This study were performed to dynamic loading tests for the thirty two piles at four different construction sites and selected pile at three site were performed to static loading tests and then compare with measured value and value of static and dynamic loading tests. The load-settlement curve form the dynamic loading tests by CAPWAP was very similar to the results obtained from the static load tests. Based on dynamic and static loading tests, the reliability of pile-driving formula were analyzed and then suggested with proper safety factor for prediction of allowable bearing capacity in this paper.

• Computers and Concrete
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• 제22권3호
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• pp.269-278
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• 2018

In the recent decades, the application of composite materials, due to their desirable properties, has increased dramatically. In the present study, a quasi-encased trapezoidal section composite steel beam encased with concrete is thoroughly examined. Calculation of the load bearing capacity is carried out by finite element modeling of concrete and FRP beams with trapezoidal section under the effect of controlled displacement loading. The results are then validated comparing to the existing experimental results obtained from similar studies. Further on, the materials are changed to steel and concrete, and the section is de-signed in such a way that both concrete and steel reach a high percent-age of their load bearing capacity. In the last step, the parameters affecting the bending capacity and the behavior of the semi-confined composite beam are investigated. Results revealed that the beam diagonal web thickness plays the most effective role in load bearing capacity amongst other studied parameters. Furthermore, by analyzing the results on the effect of different parameters, an optimal model for primary beam section is presented, which exhibits a greater load bearing capacity compared to the initial design with the same amount of materials used for both sections.