• 한국해양공학회지
• /
• 제18권6호
• /
• pp.58-69
• /
• 2004

In order to investigate the characteristics of the lateral earth pressure at rest, under hysteretic $K_o-loading/unloading$ conditions, seven types of multi-cyclic models have been studied, using dry sand. For this study, the new type of $K_o-oedometer$ apparatus was developed, and the horizontal pressure was accurately measured. The multi-cyclic models consist of primarily 3 cases: (i) $K_o-test$ under the same loading / unloading condition, (ii) multi-cyclic loading / unloading $K_o-test$ exceeding the maximum pre-vertical stress, and (iii) multi-cyclic loading / unloading $K_o-test$ within the maximum pre-vertical stress. Results fromthe multi-cyclic model indicated that a single-cyclic model could be extended if the exponents for the unloading condition $(\alpha\;and\;\alpha^*)$ and the reloading coefficients $(m_r,\;and\;m_r^{\ast})$ were primarily dependent upon the type of model, number of cycles, and the relative density.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
• /
• pp.168.1-168.1
• /
• 2005

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2001년도 춘계학술대회 논문집
• /
• pp.453-460
• /
• 2001

The seismic capacity of columns usually has been tested in uniaxial loading condition. The seismic performance used to be evaluated under the same assumption. Since the real earthquake motion is multi-directional, the effects of multi-directional excitation on the seismic capacity of structures need to be carefully examined. In this paper, a frequency dependent alternate biaxial cyclic loading test is proposed as an evaluation method of seismic capacity under multi-directional excitation. Four test specimens were made and tested to study the degradation of strength, stiffness and ductility under biaxial loading condition. A multi- directional excitation. The capacity is obtained using frequency dependent alternate biaxial cyclic loading test. The orthogonal effect is taken into account by increasing the demand.

• 한국지반공학회지:지반
• /
• 제11권1호
• /
• pp.23-40
• /
• 1995

다주기 Ko-재하/제하 시에 수평응력의 변화특성을 관찰하기 위하여 7종류의 시험모형을 선 정하였고, Ko조건을 크게 만족할 수 있도록 특별히 고안한압밀링 형태의 Ko-시험기를 제작하여 실내 건조된 모래에 대하여 실험을 수행하였다. 시험모형은 동일한 재하/제하 응력의 반복, 최대선행응력을 초과하는 반복 재하/제하, 그리고 최대선행 연직응력 내의 반복 재하/제하 Ko시험으로 구분된다. 실험결과에서 다주기 이력모형도 역시 기존의 단주기 이력모형을 확대하여 사용할 수 있음을 보였다. 여기서, 제하시의 지수 (a 및 a*)와 재재하 시의 계수(mr 및 mr*)는 응력이력의 형태, 반복회수 및 상대밀도에 따라 주로 지배되었다.

• 대한기계학회논문집A
• /
• 제30권11호
• /
• pp.1472-1478
• /
• 2006

Double-deck train has been attracted growing attention as next generation transportation around metropolis because of high passenger carrying capacity. To develop high-speed double-deck train with low operational costs, the carbody must be designed as light as possible. In addition, the carbody must be strong enough to ensure the safety of passengers. To meet these design requirements, we perform systematically weight minimization that determines thickness of aluminum extruded panels of the carbody. First, to reduce the design variables, we carry out the screening process that select sensitive or/and important design variables through design exploration. Then, weight minimization is accomplished under multi-loading condition such as vertical, compressive and torsional loads, while satisfying strength constraints of the design regulations. Finally, the result of design optimization is discussed by comparison with its initial design.

• Structural Engineering and Mechanics
• /
• 제48권2호
• /
• pp.275-289
• /
• 2013

The cross sections of multi-span beams are sometimes suddenly increased at the interior support of continuous beams to resist high negative moment. An earlier study on elastic lateral torsional buckling of stepped beams was conducted to propose new design equations. This research aims to continue the earlier study by considering the effect of inelastic buckling of stepped beams subjected to pure bending and general loading condition. A three-dimensional finite element-program ABAQUS and a statistical program MINITAB were used in the development of new design equations. The inelastic lateral torsional buckling strengths of 36 and 27 models for singly and doubly stepped beams, respectively, were investigated. The general loading condition consists of 15 loading cases based on the number of inflection point within the unbraced length of the stepped beams. The combined effects of residual stresses and geometrical imperfection were also considered to evaluate the inelastic buckling strengths. The proposed equations in this study will definitely improve current design methods for the inelastic lateral-torsional buckling of stepped beams and will increase efficiency in building and bridge design.

• 한국관개배수논문집
• /
• 제10권1호
• /
• pp.44-52
• /
• 2003

This study surveyed farming condition and the effects of nonpoint source pollution loading by cultivating in the flood control area of multi-purpose dams. According to the multi-purpose dam management regulation, cultivation can be permitted between norma

• 대한산업공학회지
• /
• 제21권2호
• /
• pp.289-298
• /
• 1995

We consider a general queueing network with multi-server stations. The stations are under heavy traffics or moderate variable conditions. We develope an algorithm to determine the optimal loading policy, which minimizes the congestion in a network. Under more specified condition, majorization and arrangement orderings are established to compare, respectively, various loading and assignment policies. Implications of results are also discussed.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.590-595
• /
• 2008

In the present paper, the impact damage behavior of steel plate reinforced concrete panels exposed to shock impulsive loading and fragment impact loading is investigated. To evaluate the retrofit performance of a steel-strengthened concrete panels, a numerical experiment using a numerical simulation with AUTODYN, an explicit analysis program is introduced because a real explosion experiment requires the vast investment and expense for facilities as well as the deformation mechanisms are too complicated to be reproduced with a conventional closed-form analyses. The model for the analysis is simplified and idealized as a two-dimensional and axisymmetric case controled with geometry, boundary condition and material properties in order to obtain a resonable computation time. As a result of the analysis, panels subject to either shock loading or fragment loading without the steel plate reinforcement experience the perforation with spalled fragments. In addition, the panels reinforced with steel plate can prevent the perforation and provide the good mechanical effect such as the increase of global stiffness and strength through the composite action between the concrete slab and the steel plate.

• Geomechanics and Engineering
• /
• 제35권4호
• /
• pp.385-393
• /
• 2023

To analyze the consolidation with horizontal sand drains, the plane strain consolidation model under multi-ramp loading is established, and its corresponding analytical solution is derived by using the separation of variables method. The proposed solution is verified by the field measurement data and finite element results. Then, the effects of the loading mode and stress distribution on consolidation and dissipation of pore pressure are investigated. At the same time, the influence of hydraulic conductivity and thickness of sand blankets on soil consolidation are also analyzed. The results show that the loading mode has a significant effect on both the soil consolidation rate and generation-dissipation process of pore water pressure. In contrast, the influence of stress distribution on pore pressure dissipation is obvious, while its influence on soil consolidation rate is negligible. To guarantee the fully drained condition of the sand blanket, the ratio of hydraulic conductivity of the sand blanket to that of clay layer k_d/k_v should range from 1.0×10⁴ to 1.0×10⁶ with soil width varying from 100 m to 1000 m. A larger soil width correspondingly needs a greater value of kd/kv to make sure that the pore water can flow through the sand blanket smoothly with little resistance. When the soil width is relatively small (e.g., less than 100 m), the effect of thickness of the sand blanket on soil consolidation is insignificant. And its influence appears obvious gradually with the increase of the soil width.