• Structural Engineering and Mechanics
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• 제90권5호
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• pp.447-458
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• 2024

This study investigated the influence of scale ratio and vertical load on the seismic performance of Puzuo joints in traditional Chinese timber structures. Three low-cyclic reversed loading tests were conducted on three scaled specimens of Bujian Puzuo in Yingxian Wooden Pagoda. This study focused on the deformation patterns and analyzed seismic performance under varying scale ratios and vertical loads. The results indicated that the slip and rotational deformations of Bujian Puzuo were the primary deformations. The scale of the specimen did not affect the layer where the maximum interlayer slip occurred, but it did decrease the proportion of slip deformation. Conversely, the reducing vertical load caused the layer with the maximum slippage and the position of the damaged Dou components to shift upward, and the proportion of slip deformation increased. When the vertical load was decreased by 3.7 times, the maximum horizontal bearing capacity under positive and negative loadings, initial stiffness, and energy dissipation of the specimen decreased by approximately 60%, 58.79%, 69.62%, and 57.93%, respectively. The horizontal bearing capacity under positive loading and energy dissipation of the specimen increased by 35.63% and 131.54%, when the specimen scale was doubled and the vertical load was increased by 15 times.

• 한국지반환경공학회 논문집
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• 제24권1호
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• pp.5-14
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• 2023

본 연구에서는 설계 대상인 현장타설말뚝기초에 대하여 상사율을 고려한 하중전이 대형토조 모형시험과 3차원 수치해석을 수행함으로써 현장타설말뚝 선단부와 주면부의 하중전이 특성을 분석하고 하중분담율을 산정하였다. 대형토조 모형시험 및 3차원 수치해석 결과에서 나타난 현장타설말뚝의 선형적 거동으로부터, 본 연구의 설계 조건에 대한 주면하중전이곡선은 Baquelin 등의 제안식, 선단하중전이곡선은 Baquelin 등의 제안식, 수평하중전이곡선은 Reese 등의 제안식이 적정한 것으로 확인되었다. 암반근입부에서 축하중은 시험값이 수치해석값보다 약간 크게 측정되었지만 암반 근입부에서 하중분담율은 연직하중이 증가함에 따라 평균적으로 약 27.8%의 분담율을 나타내었다. 연직재하 시에 말뚝두부의 침하량은 해석값이 시험값보다 약간 작게 평가되었으며, 모형시험 및 해석 최대 연직하중에서 말뚝두부의 최대 침하량은 시험치 10.6mm, 해석치 10.0mm 이고, 말뚝선단에서 최대 침하량은 시험치 2.0mm, 해석치 1.9mm로 나타났다. 수평재하 시에 기둥 두부(지표)와 말뚝 두부에서 수평변위는 시험값과 해석값이 비교적 잘 일치하는 것으로 나타났고, 모형토조시험 결과 최대 수평변위 38.0mm에서 측정된 수평하중은 24,713kN, 수치해석에서의 수평하중은 26,073kN으로 평가되었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.403-408
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• 2003

The objective of this study is to understand the variables affected the confinement for the transverse reinforcement of the reinforced concrete structural walls with the T-shaped cross section subjected to cyclic lateral loads. The structural performance of T-shaped walls was advanced by the transverse reinforcement which restrained the concrete subjected to compressive stress. If the arrangement of transverse reinforcement was not suitable for the confinement, T-shaped walls happened the brittle failure by web crushing or bucking of vertical reinforcement at the compression zone. It is necessary to confine transverse reinforcement in order to prevent the these failure. But the location of neutral axis and the magnitude of ultimate strain vary according to the section shape, a ratio of axial load, a ratio of wall cross sectional area to the floor-plan area, an aspect ratio and the reinforcement ratio. Therefore, the objective of this research is to grasp the location of neutral axis and the range which needs for the confinement of transverse reinforcement through the results of the sectional analysis which varies the ratio of axial load and the ratio of vertical reinforcement.

• 한국안전학회지
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• 제32권5호
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• pp.8-12
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• 2017

Bicycles are very popular sporting goods in these days. Thus, the durability of bicycles is very important for the safety of bicyclists. It is well known that a bicycle frame is a major component which is essential to the safety and performance of a complete bicycle. In this study, the durability of bicycle frames were experimentally investigated under the fatigue load. Eighty bicycle frames with different types and materials were prepared and tested according to EN standards. Three kinds of fatigue loads, that is, pedalling, vertical and horizontal fatigue load, which occur constantly during riding a bicycle, were applied to the bicycle frames. The experimental results show that the horizontal fatigue load was the severest mode to pass EN standard. The pass ratio of horizontal fatigue load test was 45.2%, while the pass ratio of vertical fatigue load test was 100%. Most of cracks were found at the right side of bottom bracket shell and at the intersection area between head tube and down tube. It seems that the experimental results can be applied to improve the safety and performance of a bicycle frame.

• Computers and Concrete
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• 제16권3호
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• pp.357-380
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• 2015

In this study, a simple indeterminate strut-tie model which reflects complicated characteristics of the ultimate structural behavior of continuous reinforced concrete deep beams was proposed. In addition, the load distribution ratio, defined as the fraction of applied load transferred by a vertical tie of truss load transfer mechanism, was proposed to help structural designers perform the analysis and design of continuous reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie was introduced to ensure the ductile shear failure of reinforced concrete deep beams, and the primary design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete were reflected upon. To verify the appropriateness of the present study, the ultimate strength of 58 continuous reinforced concrete deep beams tested to shear failure was evaluated by the ACI 318M-11's strut-tie model approach associated with the presented indeterminate strut-tie model and load distribution ratio. The ultimate strength of the continuous deep beams was also estimated by the experimental shear equations, conventional design codes that were based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the proposed strut-tie model and load distribution ratio was examined through the comparison of the strength analysis results classified according to the primary design variables. The present study associated with the indeterminate strut-tie model and load distribution ratio evaluated the ultimate strength of the continuous deep beams fairly well compared with those by other approaches. In addition, the present approach reflected the effects of the primary design variables on the ultimate strength of the continuous deep beams consistently and reasonably. The present study may provide an opportunity to help structural designers conduct the rational and practical strut-tie model design of continuous deep beams.

• Journal of Biosystems Engineering
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• 제8권2호
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• pp.11-17
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• 1983

Stress distribution under a driving lugged wheel was obtained by photoelastic method. The distribution showed two distinct parts, one part is due to sinkage and other due to compression. Results of the study are summarized as follows. 1. The tangential reactions of sinkage as well as compressing parts were directly proportional to tangential load to the driving wheel, that's appeared to be thrust of the driving wheel. The normal reactions of both sinkage and compressing parts were directly proportional to the vertical load to the driving wheel, that's appeared to be resistance against wheel motion. 2. When the tangential load was constant, changing the vertical load did not show any significant thrust variation of the driving wheel. 3. Under the condition of this experiment, the ratio of vertical load to tangential load (T.L/V.L) must be greater than 1.0 in order for the wheel to roll.

• 대한토목학회논문집
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• 제30권2A호
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• pp.137-148
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• 2010

본 연구에서는 기존 엑스트라도즈드교와 PSC 사장교 사이의 영역인 주탑고비 1/6~1/7의 고주탑을 적용하여 엑스트라도즈드교의 구조적, 경제적 특성을 평가하였다. 주탑고가 증가함에 따라 사재의 연직하중 분담율의 증가와 함께 변동응력도 증가하여 사재의 피로안정성이 주요 설계변수임을 알 수 있었다. 국내에서는 엑스트라도즈드교의 설계기준 부재로 인하여 일본 설계기준을 준용하고 있다. 또한, 피로 검토하중도 정립되지 않고 있어 본 연구에서는 일본 피로 검토하중에 대응하는 국내 활하중을 적용 검토하여 DL24 하중이 피로 검토하중으로 적정함을 알 수 있었다. 제시된 피로 검토하중을 적용하여 주탑고, 주거더의 강성, 케이블 면수 등을 매개변수로 엑스트라도즈드교의 구조적, 경제적 특성을 검토하였다. 본 연구의 결과로써 일면 케이블 배치가 이면 케이블 배치보다 경제적임을 알 수 있었다. 또한, 주탑고비가 1/6의 변단면 고주탑 엑스트라도즈교에서 연직 하중분담율이 30~50% 이내로 모든 사재가 허용변동응력 이내로 들어와 사재를 효율적으로 사용할 수 있어 가장 경제적임을 알 수 있었다. 본 연구를 통해 기존의 엑스트라도즈드교보다 높은 주탑고를 적용함에 따라 구조적, 경제적으로 효율성을 높일 수 있음을 확인하였다.

• 한국공간구조학회논문집
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• 제22권1호
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• pp.25-32
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• 2022

The seismic behaviors of the arch structure vary according to the rise-span ratio of the arch structure. In this study, the rise-span ratio (H/L) of the example arch structure was set to 1/4, 1/6, and 1/8. And the installation angle of the seismic isolator was set to 15°, 30°, 45°, 60° and 90°. The installation angles of the seismic isolator were set by analyzing the horizontal and vertical reaction forces according to the rise-span ratio of the arch structure. Due to the geometrical and dynamic characteristics of the arch structure, the lower the rise-span ratio, the greater the horizontal reaction force of the static load, but the smaller the horizontal reaction force of the dynamic load. And if the seismic isolator is installed in the direction of the resultant force of the reaction forces caused by the seismic load, the horizontal seismic response becomes small. Also, as the installation angle of the seismic isolator increases, the hysteresis behavior of the seismic isolator shows a plastic behavior, and residual deformation appears even after the seismic load is removed. In the design of seismic isolators for seismic response control of large space structures such as arch structures, horizontal and vertical reaction forces should be considered.

• 한국지반공학회논문집
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• 제31권10호
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• pp.49-60
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• 2015

기존 3차원 토압연구는 벽체에 작용하는 주동토압을 단일파괴체로 가정하고 벽체의 안정성에 초점을 맞춰 3차원 토압의 크기를 구하는데 역점을 두었고, 토압의 주변지반 전이에 대한 연구는 미진하였다. 따라서 본 연구에서는 벽체의 폭과 높이의 비 즉, 종횡비를 달리하여 3차원 모형실험을 수행하고, 주변지반으로 전이되는 토압의 크기와 영향범위를 파악하였다. 주변지반으로 전이되는 토압은 종횡비에 따라 3차원 주동토압의 감소량보다 17.9~30.6% 작게 나타났으며, 연직방향 토압의 전이보다 수평방향 토압의 전이가 크게 나타났다. 토압의 전이범위는 수평방향으로 주동벽체 폭 w 기준으로 0.67~1.29w, 연직방향으로 주동벽체 높이 ${\Delta}h$기준으로 약 1.0~3.0h인 것으로 나타났다. 수평방향으로 전이되는 토압은 종횡비가 같을 때 수평방향 모두 동일한 높이에서 최대치를 나타내며, 종횡비가 증가함에 따라 토압의 최대 전이 지점이 벽체 하부에서 상부로 변화하였다. 수평방향 토압의 전이는 주동벽체 폭 w 기준으로 0.25w에서 56%~79%인 것으로 나타났으며, 연직방향 토압의 전이는 주동벽체 ${\Delta}h$기준으로 1.0~1.5h에서 50%~58%인 것으로 나타났다. 종횡비에 따라 전이되는 토압의 크기와 영향범위를 분석하고 주동변위 벽체 주변으로 전달되는 3차원 하중전이 분포도를 제시하였다.

• 대한치과보철학회지
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• 제44권5호
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• pp.561-573
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• 2006

Statement of the problem: In cases of low bone level in maxilla followed by extraction due to severe periodontitis or enlarged maxillary sinus, crown-root ratio of implant prosthesis will increase. The prognosis of these cases is not good as expected. Purpose : The purpose is to compare stress distribution due to crown-root ratio and effect of splinting between two implants in maxillary molar area under different loads Material and methods: Using ITI($4.1{\times}10$ mm) implant. two finite element models were made(model S: two parallel implants, model A: one of two is 20 degree inclined). Each model was designed in different crown-root ratio(0.7:1, 1:1, 1.25:1) and set cement type gold crown to make it splinted or non-splinted clinical situations. After that, 300 N force was loaded to each model in four ways.(load 1 : middle of occlusal table, load 2 : middle of buccal cusp, load 3 : middle of lingual cusp, load 4 : horizontal load to middle of buccal cusp), and stress distribution was analyzed. Results: On all occasions, stress was concentrated on neck of implant near cortical bone. In the case of inclined implant, stress was increased compared with parallel implants. Under load 1, 2, 3, stress was not increased even when crown-root ratio increases, but under load 4, when crown-root ratio increases, stress also increased. And more stress was concentrated under load 1 than load 2, 3. When crown-root ratio was same, stress under load 1, 2, 3 decreased when splinting, but under load 4, stress did not really decrease. Conclusion: Under vertical load, stress distribution related to crown-root ratio did not change. But under horizontal load, stress increased as crown-root ratio increases. Under vertical load, splinting decreased stress but under horizontal load, effect of splinting was decreased as condition of implant changes for the worse such as increase of crown-root ratio, inclined implant.