• Title/Summary/Keyword: 설계 모멘트

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Structural Performance and Usability of Void Slab Established in T-deck Plate (T형 데크 플레이트 중공형 슬래브의 구조성능 및 사용성능)

  • Hong, Eun-Ae;Chung, Lan;Paik, In-Kwan;Yun, Sung-Ho;Cho, Seung-Ho
    • Journal of the Korea Concrete Institute
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    • v.24 no.6
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    • pp.677-684
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    • 2012
  • In recent years, extension of life span of buildings is becoming an important issue in our society. To improve the life span of buildings, rhamen structure construction and long-spanned structures are advantageous. And in order to achieve this goal, structural elements of buildings must be light and slender. As an alternative method, general porous slabs are used frequently domestically and internationally. But the study on the porous slabs using T-deck plate and assembly of light weight precast construction is insufficient at present. In this study, flexural and fatigue tests were performed on six specimens to verify structural performance and serviceability. The main parameters of the specimens were light weight and T-deck plate construction possibility as well as slab thickness. The test results indicated that the strength of porous slabs using T-deck plate and assembly of light weight were much better than general RC slabs and porous slabs without T-deck plate. And stiffness was much better than that of other tested slabs.

Studies on Behavior Characteristics of Retrofitted Cut-and-Cover Underground Station Using Centrifuge Test Results (원심모형실험을 이용한 내진 보강된 개착식 지하역사의 거동특성 연구)

  • Kim, Jin-Ho;Yi, Na-Hyun;Lee, Hoo-Seok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.2
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    • pp.24-33
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    • 2017
  • Domestic urban railway underground station structures, which were built in the 1970s ad 1980s, had been constructed as Cut-and-Cover construction system without seismic design. Because the trends of earthquake occurrence is constantly increasing all over the world as well as the Korean Peninsula, massive human casualties and severe properties and structures damage might be occurred in an non-retrofitted underground station during an earthquake above a certain scale. Therefore, to evaluate the retrofit effect and soil-structure interaction of seismic retrofitted underground station, a centrifugal shaking table test with enhanced stiffness on its structural main member are carried out on 1/60 scaled model using the Kobe and Northridge earthquakes. The seismic retrofitted members, which are columns, side walls, and slabs, are evaluated to comparing with existing non-retrofitted centrifuge test results Also, to simulate the scaled ground using variation of shear velocity according to site conditions such as ground depth and density, resonant column test is performed. From the test results, the relative displacement behavior between ground and structures shows comparatively similar in ground, but is increased on ground surface. The seismic retrofit effects were measured using relative displacements and moment behavior of column and side walls rather than slabs. Additionally, earthquake wave can be used to main design factor due to large structural deformation on Kobe earthquake wave than Norhridge earthquake wave.

Experiment and Nonlinear Analysis of DH Beams with Steel Form (외부철판이 사용된 DH Beam의 휨거동에 대한 실험 및 비선형해석)

  • Moon, Jeong-Ho;Oh, Young-Hun
    • Journal of the Korea Concrete Institute
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    • v.26 no.2
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    • pp.171-179
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    • 2014
  • The purpose of this study is to evaluate the structural performance of DH beams. DH beam construction method uses thin steel plates as form-works and structural elements. The prefabricated plates and rebars of DH beams were transported to a construction site and erected for casting concrete at the site. In this study, the contribution of steel plates to the flexural strength was evaluated since the plates were expected to play a role as reinforcements. Five test specimens were made for experimental and analytical studies. They consisted of two DH beams for the positive moment test and two DH beams for the negative moment test and a RC beam for the comparison purpose. Test results on DH beams were compared with design equations and the RC beam test result. It was proven that DH beams demonstrated the good flexural behavior showing sufficient strengths and deformation capacities. Flexural strengths, principal strains of concrete, and rebar stresses were evaluated through nonlinear finite element analyses for two test beams. The analyses also showed that steel plates can contribute to the enhancement of flexural strength of DH beams. Based on experimental and analytical studies, it was concluded that steel plates of DH beams can be used as good flexural reinforcements.

Ultimate Capacity of Guardrail Supporting Pile Subjected to Lateral Impact Load Using Centrifuge Model Test (원심모형실험을 통한 차량방호울타리 지지말뚝의 수평방향 충격하중에 대한 극한지지력)

  • Yun, Jong Seok;Lee, Min Jy;Choo, Yun Wook
    • Journal of the Korean Geotechnical Society
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    • v.35 no.11
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    • pp.25-36
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    • 2019
  • The safety barrier is installed on road embankment to prevent vehicles from falling into road side slope. Among the safety barrier, flexible guardrails are usually installed. The flexible guardrail generally consists of a protection cross-beam and supporting in-line piles. These guardrail piles are installed nearby slope edge of road embankment because the side area of the road is much narrow. The protection cross-beam absorbs impact energy caused by vehicle collision. The pile-soil interaction also absorbs the rest of the impact energy and then, finally, the flexible guardrail system resists the impact load. This paper aims to investigate the pile-soil interaction subjected to impact load using centrifuge model tests. In this study, a single pile was installed in compacted residual soil and loaded under lateral impact load. An impact loading system was designed and developed available on centrifuge tests. Using this loading system, a parametric study was performed and the parameters include types of loading and ground. Finally, the ultimate bearing capacity of supporting pile under impact load was analyzed using load-displacement curve and soil reaction pressure distributions at ultimate were evaluated and compared with previous studies.

The Reinforcing Effect of Blade Attached Pile to Support Submerged Breakwater (보강날개로 보강된 수중잠제 지지말뚝의 보강효과 분석)

  • Jeong, Sangseom;Hong, Moonhyun;Ko, Jun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.35 no.4
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    • pp.863-874
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    • 2015
  • The use of pile reinforcement is considered as one of the most promising techniques for improving load carrying capacity of piles in offshore area. In this study, to consider the horizontal and uplift bearing capacity of submerged breakwater bearing pile, exclusive analysis on load-transfer behaviour of pile was conducted. First of all, check the reinforcing effect from the three-dimensional finite element method, and estimate load transfer curve (ground reaction force). Based on these results, the reinforcing effect was quantified by estimating the coefficients of horizontal and uplift reinforcement of reinforced piles. Load transfer function with consideration of the reinforcing effect was proposed from estimated coefficients. A comparison of the analysis using the proposed load transfer function with three-dimensional finite element analysis has resulted that the proposed load transfer function is displaying good accuracy of predicting behavior of the load transfer between the pile and soil reinforcement. Interpretation of the submerged structure by applying a load transfer function considering the reinforcing effect, has shown that the reinforced pile's shear, bending moment and displacement are less than that of non-reinforced piles, while the subgrade reaction modulus arises greater. Thus, it is expected to be relatively cost effective in terms of design.

Characteristics of Tsunami Propagation through the Korean Straits and Statistical Description of Tsunami Wave Height (대한해협에서의 지진해일 전파특성과 지진해일고의 확률적 기술)

  • Cho, Yong-Jun;Lee, Jae-Il
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.18 no.4
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    • pp.269-282
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    • 2006
  • We numerically studied tsunami propagation characteristics through Korean Straits based on nonlinear shallow water equation, a robust wave driver of the near field tsunamis. Tsunamis are presumed to be generated by the earthquake in Tsuhima-Koto fault line. The magnitude of earthquake is chosen to be 7.5 on Richter scale, which corresponds to most plausible one around Korean peninsula. It turns out that it takes only 60 minutes for leading waves to cross Korean straits, which supports recently raised concerns at warning system might be malfunctioned due to the lack of evacuation time. We also numerically obtained the probability of tsunami inundation of various levels, usually referred as tsunami hazard, along southern coastal area of Korean Peninsula based on simple seismological and Kajiura (1963)'s hydrodynamic model due to tsunami-generative earthquake in Tsuhima-Koto fault line. Using observed data at Akita and Fukaura during Okushiri tsunami in 1993, we verified probabilistic model of tsunami height proposed in this study. We believe this inundation probability of various levels to give valuable information for the amendment of current building code of coastal disaster prevention system to tame tsunami attack.

Numerical Analysis for Fault Reactivation during Gas Hydrate Production (가스하이드레이트 개발과정에서의 단층 재활성화 해석)

  • Kim, Hyung-Mok;Kim, A-Ram
    • Tunnel and Underground Space
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    • v.26 no.2
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    • pp.59-67
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    • 2016
  • In this paper, we perform a numerical analysis to evaluate the potential of fault reactivation during gas production from hydrate bearing sediments and the moment magnitude of induced seismicity. For the numerical analysis, sequential coupling of TOUGH+Hydrate and FLAC3D was used and the change in effective stress and consequent geomechanical deformation including fault reactivation was simulated by assuming that Mohr-Coulomb shear resistance criterion is valid. From the test production simulation of 30 days, we showed that pore pressure reduction as well as effective stress change hardly induces the fault reactivation in the vicinity of a production well. We also investigated the influence of stress state conditions to a fault reactivation, and showed that normal fault stress regime, where vertical stress is relatively greater than horizontal, may have the largest potential for the reactivation. We tested one simulation that earthquake can be induced during gas production and calculated the moment magnitude of the seismicity. Our calculation presented that all the magnitudes from the calculation were negative values, which indicates that induced earthquakes can be grouped into micro-seismic and as small as hardly perceived by human beings. However, it should be noted that the current simulation was carried out using the highly simplified geometric model and assumptions such that the further simulations for a scheduled test production and commercial scale production considering complex geometric conditions may produce different results.

Bivariate Frequency Analysis of Rainfall using Copula Model (Copula 모형을 이용한 이변량 강우빈도해석)

  • Joo, Kyung-Won;Shin, Ju-Young;Heo, Jun-Haeng
    • Journal of Korea Water Resources Association
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    • v.45 no.8
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    • pp.827-837
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    • 2012
  • The estimation of the rainfall quantile is of great importance in designing hydrologic structures. Conventionally, the rainfall quantile is estimated by univariate frequency analysis with an appropriate probability distribution. There is a limitation in which duration of rainfall is restrictive. To overcome this limitation, bivariate frequency analysis by using 3 copula models is performed in this study. Annual maximum rainfall events in 5 stations are used for frequency analysis and rainfall depth and duration are used as random variables. Gumbel (GUM), generalized logistic (GLO) distributions are applied for rainfall depth and generalized extreme value (GEV), GUM, GLO distributions are applied for rainfall duration. Copula models used in this study are Frank, Joe, and Gumbel-Hougaard models. Maximum pseudo-likelihood estimation method is used to estimate the parameter of copula, and the method of probability weighted moments is used to estimate the parameters of marginal distributions. Rainfall quantile from this procedure is compared with various marginal distributions and copula models. As a result, in change of marginal distribution, distribution of duration does not significantly affect on rainfall quantile. There are slight differences depending on the distribution of rainfall depth. In the case which the marginal distribution of rainfall depth is GUM, there is more significantly increasing along the return period than GLO. Comparing with rainfall quantiles from each copula model, Joe and Gumbel-Hougaard models show similar trend while Frank model shows rapidly increasing trend with increment of return period.

Structural Analysis of a Suction Pad for a Removable Bike Carrier using Computational and Experimental Methods (탈착식 자전거 캐리어용 흡착 패드의 실험 및 전산적 방법을 활용한 구조해석)

  • Suh, Yeong Sung;Lim, Geun Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.3
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    • pp.622-628
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    • 2016
  • As the suction pad-supporting bike carrier attached to a car may be subject to an excessive dynamic load due to random vibrations and centrifugal forces during driving, its structural safety is of great concern. To examine this, the finite-element method with a fluid-structure interaction should be used because the pressure on the pad bottom is changed in real time according to the fluctuations of the force or the moment applied on the pad. This method, however, has high computing costs in terms of modeling efforts and software expense. Moreover, the accuracy of computation is not easily guaranteed. Therefore, a new method combining the experiment and computation is proposed in this paper: the bottom pressure and contact area of the pad under varying loads was measured in real time and the acquired data are then used in the nonlinear elastic finite-element calculations. The computational and experimental results obtained with the product under development showed that the safety margin of the pad under the axial loading is relatively sufficient, whereas with an excessive rotational loading, the pad is vulnerable to separation or a local surface damage; hence, the safety margin may not be secured. The predicted contact behavior under the variation of the magnitude and type of the loading were in good agreement with the one from the experiment. The proposed analysis method in this study could be used in the design of similar vacuum pad systems.

Cyclic Loading Test for TSC Beam - PSRC Column Connections (TSC 합성보 - PSRC 합성기둥 접합부에 대한 주기하중 실험)

  • Hwang, Hyeon Jong;Eom, Tae Sung;Park, Hong Gun;Lee, Chang Nam;Kim, Hyoung Seop
    • Journal of Korean Society of Steel Construction
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    • v.25 no.6
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    • pp.601-612
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    • 2013
  • In the present study, details of the TSC beam-to-PSRC column connection for low and middle seismic zones were developed. For ease construction, the top and bottom flanges of the steel section of the TSC beam were discontinuous at the joint face on purpose, while the web passes through the joint. Thus, tensile resistance of the top and bottom flanges is not considered in the calculation of nominal strength of the connection. Cyclic loading tests on two interior connections and an exterior connection were performed to verify the seismic performance. The test parameter for two interior connections was the depth of the TSC beams: 600 and 700 mm including the slab depth. The test results showed that the nominal strength of the connections predicted by KBC 2009 correlated well with the test results. The connection specimens exhibited relatively good deformation and energy dissipation capacities, greater than the requirements for the ordinary and intermediate moment frames. Ultimately, the connection specimens were failed at the story drift ratios of 3.0 to 4.0 % due to local buckling and tensile fracture of the web of the TSC beam passing through the joint. By modifying the existing provisions of ASCE, the joint shear strength of the TSC beam-PSRC column connection was evaluated.