• Title/Summary/Keyword: load test

Search Result 8,113, Processing Time 0.039 seconds

Effects of increasing weight load on dynamic balance (무게부하 증가가 동적 균형에 미치는 영향)

  • Woong-Jae Choi;Byung-Hoon Woo
    • Journal of the Korean Applied Science and Technology
    • /
    • v.40 no.4
    • /
    • pp.606-615
    • /
    • 2023
  • The purpose of this study was to investigate the effect of increasing weight load on the dynamic balance on Y-balance Test(YBT). 18 male and female adults in their 20-30s (age: 23.17±1.72 years, height: 172.46±9.84 cm, weight: 73.39±11.44 kg, leg length: 88.89±5.69 cm) participated in the experiment. To measure the dynamic balance, the YBT was used to measure the reach distance, composite score, and COP variables to derive the results. As a result of the study, dynamic balance was improved in weight load in posteromedial and posterolateral reach and overall score during YBT. As a result of COP, anteroposterior amplitude, left and right COP velocity, and COP area during anterior reach improved dynamic balance in weight load in the right foot, but there was no difference during the posteromedial reach, ML amplitude in the left foot, AP COP velocity in left foot, ML COP velocity and COP velocity in both foot, and COP area in both foot improved dynamic balance when weight load during posterolateral reach.

A Study on the Safety of Highway Bridges by the Primary Capacity of Load (기본내하력에 의한 도로교의 안전성 연구)

  • 채원규
    • Journal of the Korean Society of Safety
    • /
    • v.11 no.4
    • /
    • pp.122-126
    • /
    • 1996
  • In this thesis, the field test results of fifty-one highway bridges were analyzed in order to Investigate the primary capacity of load of highway bridges. From this study, it was known that primary capacity of load are decreased with the serviced years, and those are small in T-beam bridges rather than I-beam bridges. And the average primary capacity of load of highway bridges is seemd about 15. 5ton in T-beam bridges and in I-beam bridges about 19.7ton.

  • PDF

An Experimental Study on Bearing Capacity of Drilled Shaft with Mid-size (중구경 현장타설말뚝의 지지력 특성에 관한 실험적 연구)

  • Lee, Kwang-Wu;You, Seung-Kyong;Park, Jeong-Jun;Yun, Jung-Mann;Hong, Gigwon
    • Journal of the Korean Geosynthetics Society
    • /
    • v.18 no.4
    • /
    • pp.263-272
    • /
    • 2019
  • This paper describes the results of bearing capacity using field loading test of pile, in order to extend the applicability of drilled shaft with mid-size, and the results were compared with the prediction results of design bearing capacity by empirical formular. The static load test result showed that the allowable bearing capacity of high pile strength was about 2.4 times higher than that of low pile strength. The dynamic load test result showed that the allowable bearing capacity of high pile strength was about 1.4 times~1.5 times higher than that of low pile strength. The comparison result of allowable bearing capacity between static and dynamic load test showed that the difference of allowable load ranged from 3% to 6% under the same settlement conditions. As a result of comparing the ultimate bearing capacity by load test and design bearing capacity, it was found that the FHWA proposed equation could be more reasonable than the other proposed equation in load sharing ratios of end bearing and skin friction.

Accelerated Life Test Selection Study for Life Evaluation of Engine Type Drive Axle for Forklift (지게차용 엔진식 드라이브 액슬 수명평가를 위한 가속수명시험 선정 연구)

  • Jun-Young Kim;Yeong Jun Yu;Chul-Hee Lee
    • Journal of Drive and Control
    • /
    • v.20 no.3
    • /
    • pp.9-14
    • /
    • 2023
  • In this paper, the selection of a reliable accelerated life test code for a 2-ton forklift was accomplished by choosing the driving resistance coefficient failure-free test time based on a 10,000-hour B10 life. The overall life and average equivalent load of the vehicle were then calculated based on actual driving test conditions using the selected driving resistance coefficient. The gear train's accelerated life test code was selected by adjusting the equivalent load to a torque and rotation speed that did not exceed 125%(about 75HP) of the vehicle rated power. The safety of the test standards was validated by conducting an actual accelerated life test utilizing the proposed test method in this study and comparing the test result with the corresponding theoretical value. It is anticipated that the reliability of the accelerated life test in this paper will be enhanced, by incorporating actual driving performance data collected directly from the forklift and adjusting the conditions used in developing the accelerated life test code.

Experimental study on the longitudinal load transfer of a shallow tunnel depending on the deformation tunnel face (I) (얕은 터널의 굴진면 변형에 따른 종방향 하중전이 특성에 대한 실험적 연구(I))

  • Kim, Yang Woon;Lee, Sang Duk
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.18 no.5
    • /
    • pp.487-497
    • /
    • 2016
  • If a tunnel is excavated, the released stress is redistributed in the ground around the tunnel face, which lead the stress state of the surrounding ground of the tunnel and the load acting on the tunnel support to change. If the tunnel face deforms, the ground ahead of it is relaxed, and the earth pressure acting on it decreases. And if the displacement increases so much that, the ground ahead of the tunnel face reaches in failure state. At this time, load would be transferred longitudinally in the tunnel, depending on the cover and the face deformations. The longitudinal load transfers in the tunnels induced by the tunnelling has been often studied; however, the relation between the deformation of the tunnel face and the longitudinal load transfer was rarely studied. Therefore in this study assesses the characteristics of the longitudinal load transfer as the face was failed by displacement by conducting a model test in a shallow tunnel. In other words, the longitudinal load transfer of the tunnel with the progress of the face deform was measured by conducting a model test, beginning at the state of earth pressure at rest. As results of this study, most of the longitudinal load transfers occurred drastically at the beginning of the displacement of the tunnel face, and as the displacement of the face approached the ultimate displacement, it converged to the ultimate displacement at a gentler slope. In other words, when the ground ahead of the tunnel face was still in an elastic state, the longitudinally transferred load increased sharply at the beginning stage but it tended to increase gradually if it approached to the ultimate limit. Thus, it was noted that the earth pressure in the face and the longitudinal load transfer of the tunnel had the same decreasing tendency.

Load Transfer Mechanism of Drilled Shafts in Weathered Rock (풍화된 암반에 근입된 현장타설말뚝의 하중전이 기구)

  • Kwon, Oh-Sung;Cho, Sung-Min;Jung, Sung-Jun;Kim, Myoung-Mo
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2005.03a
    • /
    • pp.57-64
    • /
    • 2005
  • Since the allowable bearing capacities of piles in weathered/fractured rock are mainly governed by settlement, the load-displacement behavior of the rock socketed pile should be well known. To predict pile head settlement at the design stage, the exact understanding of the load-transfer mechanisms is essential. Therefore, in this research, the load-transfer mechanisms of drilled shaft socketed into weathered rock was investigated. For that, 5 cast-in-place concrete piles with diameters of 1,000 mm were socketed into weathered gneiss. The static axial load tests and the load-transfer measurements were performed to examine the axial resistant behavior of the piles. A comprehensive field/laboratory testing program on weathered rock at the field test sites was also performed to describe the in situ rock mass conditions quantitatively. And then, the effect of rock mass condition on the load transfer mechanism was investigated. The side shear resistance of the pile in moderately weathered rock reached to yielding point at a few millimeter displacements, and after that, the rate of resistance increment dramatically decreased. However, that in the highly /completely weathered rock did not show the obvious yielding point, and gradually increased showing the hyperbolic pattern until with the relatively high displacement (>10 mm). The end bearing-displacement curves showed linear increase at least until with the base displacement of approximately 10 mm, regardless rock mass conditions.

  • PDF

Shear Load-Transfer Function of Rock-Socketed Drilled Shafts Considering Borehole Roughness (굴착면 거칠기를 고려한 암반 근입 현장타설말뚝의 주면 하중전이함수 제안)

  • Seol, Hoon-Il;Woo, Sang-Yoon;Han, Keun-Taek;Jeong, Sang-Seom
    • Journal of the Korean Geotechnical Society
    • /
    • v.22 no.7
    • /
    • pp.23-35
    • /
    • 2006
  • Shear load transfer characteristics of rock-socketed drilled shafts were analyzed. The constant normal stiffness (CNS) direct shear tests were performed to identify the major influencing factors of shaft resistance, i.e., unconfined compressive strength, borehole roughness, normal stiffness, initial confining stress, and material properties. Based on the CNS tests, shear load transfer function of drilled shafts in rocks is proposed using borehole roughness and the geological strength index (GSI), which indicates discontinuity and surface condition of rock mass in Hoek-Brown criterion (1997). The proposed load-transfer function was verified by the load test results of seven rock-socketed drilled test shafts subjected to axial loads. Through comparisons of the results of load tests, it is found that the load-transfer function by the present study is in good agreement with the general trend observed by in situ measurements, and thus represents a significant improvement in the prediction of load transfer of drilled shafts.

Stability of suspension bridge catwalks under a wind load

  • Zheng, Shixiong;Liao, Haili;Li, Yongle
    • Wind and Structures
    • /
    • v.10 no.4
    • /
    • pp.367-382
    • /
    • 2007
  • A nonlinear numerical method was developed to assess the stability of suspension bridge catwalks under a wind load. A section model wind tunnel test was used to obtain a catwalk's aerostatic coefficients, from which the displacement-dependent wind loads were subsequently derived. The stability of a suspension bridge catwalk was analyzed on the basis of the geometric nonlinear behavior of the structure. In addition, a full model test was conducted on the catwalk, which spanned 960 m. A comparison of the displacement values between the test and the numerical simulation shows that a numerical method based on a section model test can be used to effectively and accurately evaluate the stability of a catwalk. A case study features the stability of the catwalk of the Runyang Yangtze suspension bridge, the main span of which is 1490 m. Wind can generally attack the structure from any direction. Whenever the wind comes at a yaw angle, there are six wind load components that act on the catwalk. If the yaw angle is equal to zero, the wind is normal to the catwalk (called normal wind) and the six load components are reduced to three components. Three aerostatic coefficients of the catwalk can be obtained through a section model test with traditional test equipment. However, six aerostatic coefficients of the catwalk must be acquired with the aid of special section model test equipment. A nonlinear numerical method was used study the stability of a catwalk under a yaw wind, while taking into account the six components of the displacement-dependent wind load and the geometric nonlinearity of the catwalk. The results show that when wind attacks with a slight yaw angle, the critical velocity that induces static instability of the catwalk may be lower than the critical velocity of normal wind. However, as the yaw angle of the wind becomes larger, the critical velocity increases. In the atmospheric boundary layer, the wind is turbulent and the velocity history is a random time history. The effects of turbulent wind on the stability of a catwalk are also assessed. The wind velocity fields are regarded as stationary Gaussian stochastic processes, which can be simulated by a spectral representation method. A nonlinear finite-element model set forepart and the Newmark integration method was used to calculate the wind-induced buffeting responses. The results confirm that the turbulent character of wind has little influence on the stability of the catwalk.

Shear Load Transfer Characteristics of Drilled Shafts in Weathered Rocks (풍화암에 근입된 현장타설 말뚝의 하중 전이 특성)

  • Jeong, Sang-Seom;Cho, Sung-Han;Kim, Soo-Il
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2000.03a
    • /
    • pp.85-106
    • /
    • 2000
  • The load distribution and deformation of drilled shafts subjected to axial loads were evaluated by a load transfer approach. The emphasis was on quantifying the load transfer mechanism at the interface between the shafts and surrounding highly weathered rocks based on a numerical analysis and small-scale tension load tests performed on nine instrumented piles. An analytical method that takes into account the soil coupling effect was developed using a modified Mindlin's point load solution. Based on the analysis, a single-modified hyperbolic model is proposed for the shear transfer function of drilled shafts in highly weathered rocks. Through comparisons with field case studies, it is found that the prediction by the present approach is in good agreement with the general trend observed by in-situ measurements.

  • PDF

Load Balancer Performance Testing and Analysis for Improving Web Server Performance (웹서버 성능 향상을 위한 로드 발란서 성능 연구)

  • 장동원;조평동
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.5 no.6
    • /
    • pp.1073-1077
    • /
    • 2001
  • In this paper, we tested and analysed the performance of the load balancer which advances the performance of web server farm. Load balancer distributes the traffic that is inputting from internet and accepts client's connection requests to its maximum capacity. Then we test the maximum connection requests per second that load balancer processed and the load balancing that established with the load balancer.

  • PDF