• Title/Summary/Keyword: vertical shear force

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Behavior of Reinforced Concrete Inclined Column-Beam Joints (철근콘크리트 경사기둥-보 접합부의 거동)

  • Kwon, Goo-Jung;Park, Jong-Wook;Yoon, Seok-Gwang;Kim, Tae-Jin;Lee, Jung-Yoon
    • Journal of the Korea Concrete Institute
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    • v.24 no.2
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    • pp.147-156
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    • 2012
  • In recent years, many high-rise buildings have been constructed in irregular structural system with inclined columns, which may have effect on the structural behavior of beam-column joints. Since the external load leads to shear and flexural forces on the inclined columns in different way from those on the conventional vertical columns, failure mode, resistant strength, and ductility capacity of the inclined column-beam joints may be different than those of the perpendicular beam-column joints. In this study, six RC inclined beam-column joint specimens were tested. The main parameter of the specimens was the angle between axes of the column and beam (90, 67.5, and 45 degree). Test results indicated that the structural behavior of conventional perpendicular beam-column joint was different to that of the inclined beam-column joints, due to different loading conditions between inclined and perpendicular beam-column joints. Both upper and lower columns of perpendicular beam-column joints were subjected to compressive force, while the upper and lower columns of the inclined beam-column joints were subjected to tensile and compressive forces, respectively.

The Structure of Oriental Wooden Pagoda (동양목조탑파(東洋木造塔婆)의 구조형식(構造形式)에 관한 연구(硏究) - 법주사(法住寺) 팔상전(捌相殿)과 법륭사(法隆寺) 오중탑(五重塔)의 비교분석적 측면에서 -)

  • Kim, Kyeong-Pyo;Fujii, Keisuke;Lee, Min-Sup
    • Journal of architectural history
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    • v.1 no.1 s.1
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    • pp.88-105
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    • 1992
  • This dissertation aims to investigate the structure of Palsangjeon, a five story wooden pagoda in Pubjoo Temple which is the only wooden pagoda existing in Korea, by a comparative study of the Palsangjeon with Japanese counterparts. By doing so, the writer of the present investigation attempts to find out its structural originality. The main finding of this study are as follows. The upper part of Palsangjeon is constructed with square log frameworks called GuiTl and Sacheon-Ju around the central column. The four walls along Sacheon-Ju from the 1st level to the 3rd well resists the outside horizontal piressure. And Gui-Tl structure on the 5th level copes much better with shear force. So this frame consisting of Sacheon-Ju and log frameworks might be viewed an semi-core system, This core is supported once again by the frame of Go-Ju. That is to say. Go-Ju supports frame of Sacheon-Ju. And the frame of Pyeong-Ju on the 4th and the 5th levels also supports it. The frame of Go-Ju is supported by the frame of Pyeong-Ju on the 1st and the 2nd levels. So this structure is designed to resist the wind and also keep the balance by properly distributing vertical pressure. The plan and the elevational structure of Palsangjeon keep the balance by the perfect symmetric structure. And the frame of Sacheon-Ju forming semi-core system can resist both the lateral load and the vertical pressure for the balance of its structure. The five story pagoda in Horyuji used to stand on a central which is desigend to support the main body of the pagoda from the first level. The principles of balance is used between the Ha-Aag and short to react the rafter. Sacheon-Ju and edge column is against the lateral load. The structural jointing system is stable thanks to the log framewroks formed on every level. The five story pagoda in Horyuji poseses the structual system originated from the ancient wooden pagoda. The pagoda is found to express simple, sincere and straight forward form. On the other hand, it could be seen as a stucture resisting the earthquake and the lateral load, Palsangjeon is an excellent building which religions function is well harmonized with its structure and appearance. It not only functions extremely well as a regions place like other pagodas, but also excellently shows how multi-story wooden building should be structured.

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Investigation of Post-seismic Sites Using Local Seismic Tomography in the Korean Peninsula (지진 토모그래피를 이용한 한반도의 과거진원지역의 특성 연구)

  • Kim So-Gu;Bae Hyung-Sub
    • Economic and Environmental Geology
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    • v.39 no.2 s.177
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    • pp.111-128
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    • 2006
  • Three dimensional crustal structure and source features of earthquake hypocenters on the Korean peninsula were investigated using P and S-wave travel time tomography. The main goal of this research was to find Vp/Vs anomalies at earthquake hypocenters as well as those of crustal structure of basins and deep tectonic settings. This allowed fer the extrapolation of more detailed seismotectonic force from the Korean peninsula. The earthquake hypocenters were found to have high Vp/Vs ratio discrepancies (VRD) at the vertical sections. High V/p/Vs ratios were also found in the sedimentary basins and beneath the Chugaryong Rift Zone (CRZ), which was due to mantle plume that subsequently solidified with many fractures and faults which were saturated with connate water. The hypocenters of most earthquakes were found in the upper crust for Youngwol (YE), Kyongju (KE), Hongsung (HE), Kaesong (KSE), Daekwan (DKE), and Daehung (DHE) earthquakes, but near the subcrust or the Moho Discontinuity for Mt. Songni (SE), Sariwon (SRE) and Mt. Jiri (JE) earthquakes. Especially, we found hot springs of the Daekwan, Daehung and Unsan regions coincide with high VRD. Also, this cannot rule out the possibility that there are some partial meltings in the subcrust of this region. High VRD might indicate that many faults and fractures with connate water were dehydrated when earthquakes took place, reducing shear modulus in the hypocenter areas. This is can be explained by due to the fact that a point source which is represented by the moment tensor that may involve changes in volume, shear fracture, and rigidity. High Vp/Vs ratio discrepancies (VRD) were also found beneath Mt. Backdu beneath 40 km, indicating that magma chamber existed beneath Mt. Backdu is reducing shear modulus of S-wave velocity.

Analysis on the behavior of shield TBM cable tunnel: The effect of the distance of backfill grout injection from the end of skin plate (뒷채움 주입 거리에 따른 전력구 쉴드 TBM 터널의 거동 특성 분석)

  • Cho, Won-Sub;Song, Ki-Il;Ryu, Hee-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.2
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    • pp.213-224
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    • 2014
  • Recently, tunnelling with TBM is getting popular for the construction of cable tunnel in urban area. Mechanized tunnelling method using shield TBM has various advantages such as minimization of ground settlement and prevention of vibration induced by blasting that should be accompanied by conventional tunnelling. In Korea, earth pressure balance (EPB) type shield TBM has been mainly used. Despite the popularity of EPB shield TBM for cable tunnel construction, study on the mechanical behavior of cable tunnel driven by shield TBM is insufficient. Especially, the effect of backfill grout injection on the behavior of cable tunnel driven by shield TBM is investigated in this study. Tunnelling with shield TBM is simulated using 3D FEM. The distance of backfill grout injection from the end of shield skin varies. Sectional forces such as axial force, shear force and bending moment are monitored. Vertical displacement at the ground surface is measured. Futhermore, the relation between volume loss and the distance of backfill grout injection from the end of skin plate is derived. Based on the stability analysis with the results obtained from the numerical analysis, the most appropriate injection distance can be obtained.

Pushover Analysis of an Unbraced 5-Story Steel Framed Structure for Arrangement of Semi-Rigid Connection (반강접 접합부 배치에 따른 비가새 5층 철골골조구조물의 비탄성 정적해석)

  • Kang, Suk-Bong;Kim, Sin-Ae
    • Journal of Korean Society of Steel Construction
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    • v.22 no.4
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    • pp.325-334
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    • 2010
  • In this study, an unbraced five-story steel-framed structure was designed in accordance with KBC2005 to understand the features of structural behavior for the arrangement of semi-rigid connections. A pushover analysis of the structural models was performed, wherein all the connections were idealized as fully rigid and semi-rigid. Additionally, horizontal and vertical arrangements of the semi-rigid connection were adopted for the models. A fiber model was utilized for the moment-curvature relationship of the steel beam and the column, and a three-parameter power model was adopted for the moment-rotation angle of the semi-rigid connection. The top displacement, base-shear force, required ductility for the connection, sequence of the plastic hinge, and design factors such as the overstrength factor, ductility factor, and response modification coefficient were investigated using the pushover analysis of a 2D structure subjected to the equivalent static lateral force of KBC2005. The partial arrangement of the semi-rigid connection was found to have secured higher strength and lateral stiffness than that of the A-Semi frame, and greater ductility than the A-Rigid frame. The TSD connection was found suitable for use for economy and safety in the sample structure.

Non-linear Time History Analysis of Piloti-Type High-rise RC Buildings (필로티형 고층 RC건물의 비선형시간이력해석)

  • Ko, Dong-Woo;Lee, Han-Seon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.1
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    • pp.35-43
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    • 2009
  • Two types of piloti-type high-rise RC building structures having irregularity in the lower two stories were selected as prototypes, and nonlinear time history analysis was performed using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. One of the buildings studied had a symmetrical moment-resisting frame (BF), while the other had an infilled shear wall in only one of the exterior frames (ESW). A fiber model, consisting of concrete and reinforcing bar represented from the stress-strain relationship, was adapted and used to simulate the nonlinearity of members, and MVLEM (Multi Vertical Linear Element Model) was used to simulate the behavior of the wall. The analytical results simulate the behavior of piloti-type high-rise RC building structures well, including the stiffness and yield force of piloti stories, the rocking behavior of the upper structure and the variation of the axial stiffness of the column due to variation in loading condition. However, MVLEM has a limitation in simulating the abrupt increasing lateral stiffness of a wall, due to the torsional mode behavior of the building. The design force obtained from a nonlinear time history analysis was shown to be about $20{\sim}30%$ smaller than that obtained in the experiment. For this reason, further research is required to match the analytical results with real structures, in order to use nonlinear time history analysis in designing a piloti-type high-rise RC building.

The study on the effect of fracture zone and its orientation on the behavior of shield TBM cable tunnel (단층파쇄대 규모 및 조우 조건에 따른 전력구 쉴드 TBM 터널의 거동 특성 분석)

  • Cho, Won-Sub;Song, Ki-Il;Kim, Kyoung-Yul
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.4
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    • pp.403-415
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    • 2014
  • Recently, the temperature rise in the summer due to climate change, power usage is increasing rapidly. As a result, power generation facilities have been newly completed and the need for ultra-high-voltage transmission line for power transmission of electricity to the urban area has increased. The mechanized tunnelling method using a shield TBM have an advantage that it can minimize vibrations transmitted to the ground and ground subsidence as compared with the conventional tunnelling method. Despite the popularity of shield TBM for cable tunnel construction, study on the mechanical behavior of cable tunnel driven by shield TBM is insufficient. Thus, in this study, the effect of fractured zone ahead of tunnel face on the mechanical behavior of the shield TBM cable tunnel is investigated. In addition, it is intended to compare the behavior characteristics of the fractured zone with continuous model and applying the interface elements. Tunnelling with shield TBM is simulated using 3D FEM. According to the change of the direction and magnitude of the fractured zone, Sectional forces such as axial force, shear force and bending moment are monitored and vertical displacement at the ground surface is measured. Based on the stability analysis with the results obtained from the numerical analysis, it is possible to predict fractured zone ahead of the shield TBM and ensure the stability of the tunnel structure.

Evaluation of Inertial Interaction of a Multi-degree-of-freedom Structure during a Large-scale 1-g Shaking Table Test (대형 진동대 실험을 이용한 다자유도 구조물의 관성 상호작용 평가)

  • Chae, Jonghoon;Yoon, Hyungchul;Jung, Jongwon
    • Journal of the Korean Geotechnical Society
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    • v.38 no.6
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    • pp.17-28
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    • 2022
  • The effect of the soil-structure interaction (SSI) on has been recently evaluated in shaking table tests. However, most of these tests were conducted on single-degree-of-freedom (SDOF) superstructures and a single-pile. This study investigates the inertial interaction effect of a multi-degree-of-freedom (MDOF) superstructure system with a group piles on a large-scale shaking table test. Whereas the SDOF superstructure system shows a single-frequency amplification tendency, the MDOF superstructure system exhibited amplification tendencies of the acceleration phase and frequency responses for multiple frequencies. In addition, the amplification phenomenon between the footing and the column-type superstructure exceeded that between the footing and the wall-type superstructure, indicating a greater inertial interaction effect of the column-type superstructure. The relationship between shear force and inertial force, the relative vertical and horizontal displacements on the footing was figured out. Also, the ananlysis of dynamic p-y curve at each depth was conducted. In summary, the MDOF and SDOP superstructure systems exhibited different behaviors and the column-type superstructure exerted a higher interaction effect than the wall-type superstructure.

Numerical Study on Lateral Pile Behaviors of Piled Gravity Base Foundations for Offshore Wind Turbine (수치해석을 통한 해상풍력 말뚝지지중력식기초의 수평거동 분석)

  • Seo, Ji-Hoon;Choo, Yun Wook;Goo, Jeong-Min;Kim, Youngho;Park, Jae Hyun
    • Journal of the Korean Geotechnical Society
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    • v.32 no.11
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    • pp.5-19
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    • 2016
  • This paper presents the results from three-dimensional finite element (FE) analysis undertaken to provide insight into the lateral behaviors of piled gravity base foundation (GBF) for offshore wind turbine. The piled GBF was originally developed to support the gravity based foundation in very soft clay soil. A GBF is supported by five piles in a cross arrangement to achieve additional vertical bearing capacity. This study considered four different cases including a) single pile, b) three-by-three group pile (with nine piles), c) cross-arrangement group pile (with five piles), and d) piled GBF. All the cases were installed in homogenous soft clay soil with undrained shear strength of 20 kPa. From the numerical results, p-y curves and thus P-multiplier was back-calculated. For the group pile cases, the group effect decreased with increasing the number of piles. Interestingly, for the piled GBF, the P-multipliers showed a unique trend, compared to the group pile cases. This study concluded that the global lateral behaviour of the piled GBF was influenced strongly by the interaction between GBF and contacted soil surface.

Experimental Study for Confirmation of Relaxation Zone in the Underground Cavity Expansion (지중 내 공동 확장에 따른 이완영역 확인을 위한 실험적 연구)

  • Kim, Youngho;Kim, Hoyeon;Kim, Yeonsam;You, Seung-Kyong;Han, Jung-Geun
    • Journal of the Korean Geosynthetics Society
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    • v.16 no.4
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    • pp.231-240
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    • 2017
  • Recently, there have been frequent occurrences of ground sink in the urban area, which have resulted in human and material damage and are accompanied by economic losses. This is caused by artificial factors such as soil loss, poor compaction, horizontal excavation due to the breakage of the aged sewage pipe, and lack of water proof at vertical excavation. The ground sink can be prevented by preliminary restoration and reinforcement through exploration, but it can be considered that it is not suitable for urgent restoration by the existing method. In this study, a model experiment was carried out to simulate the in-ground cavities caused by groundwater flow for developing non-excavation urgent restoration in underground cavity and the range of the relaxation zone was estimated by detecting the around the cavity using a relaxation zone detector. In addition, disturbance region and relaxation region were separated by injecting gypsum into cavity formed in simulated ground. The shape of the underground cavity due to the groundwater flow was similar to that of the failure mode III formed in the dense relative density ground due to water pipe breakage in the previous study. It was confirmed that the relaxed region detected using the relaxation zone detector is formed in an arch shape in the cavity top. The length ratio of the relaxation region to the disturbance region in the upper part of the cavity center is 2: 1, and it can be distinguished by the difference in the decrease of the shear resistance against the external force. In other words, it was confirmed that the secondary damage should not occur in consideration of the expandability of the material used as the injecting material in the pre-repair and reinforcement, and various ground deformation states will be additionally performed through additional experiments.