• Title/Summary/Keyword: axial stiffness

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A Study on the Conceptual Design for the Material Substitution of Rolling Stock Structures (소재대체를 이용한 철도 차량구조의 개념설계 연구)

  • 구정서
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.17 no.2
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    • pp.171-181
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    • 2004
  • This paper developed the theoretical method to predict structural performances and weight reduction rates of a carbody when its materials should be substituted. For the material substitution design of the carbody, the bending, axial and twisting deformations are evaluated under the constant stiffness and strength conditions. For the design of the primary structures such as the center beams, the cross beams and the cantrails, the bending and axial deformations are investigated under the condition of the constant bending stiffness, the constant bending or buckling strength by considering both the material properties and the cross sectional shapes. The developed indices to measure the weight reduction by the material substitution give good informations on the weak and strong points of a carbody design.

Hysteresis of concrete-filled circular tubular (CFCT) T-joints under axial load

  • Liu, Hongqing;Shao, Yongbo;Lu, Ning;Wang, Qingli
    • Steel and Composite Structures
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    • v.18 no.3
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    • pp.739-756
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    • 2015
  • This paper presents investigations on the hysteretic behavior of concrete-filled circular tubular (CFCT) T-joints subjected to axial cyclic loading at brace end. In the experimental study, four specimens are fabricated and tested. The chord members of the tested specimens are filled with concrete along their full length and the braces are hollow section. Failure modes and load-displacement hysteretic curves of all the specimens obtained from experimental tests are given and discussed. Some indicators, in terms of stiffness deterioration, strength deterioration, ductility and energy dissipation, are analyzed to assess the seismic performance of CFCT joints. Test results indicate that the failures are primarily caused by crack cutting through the chord wall, convex deformation on the chord surface near brace/chord intersection and crushing of the core concrete. Hysteretic curves of all the specimens are plump, and no obvious pinching phenomenon is found. The energy dissipation result shows that the inelastic deformation is the main energy dissipation mechanism. It is also found from experimental results that the CFCT joints show clear and steady stiffness deterioration with the increase of displacement after yielding. However, all the specimens do not perform significant strength deterioration before failure. The effect of joint geometric parameters ${\beta}$ and ${\gamma}$ of the four specimens on hysteretic performance is also discussed.

Wind-resistant performance of cable-supported bridges using carbon fiber reinforced polymer cables

  • Zhang, Xin-Jun;Ying, Lei-Dong
    • Wind and Structures
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    • v.10 no.2
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    • pp.121-133
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    • 2007
  • To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are schemed, in which the cable's cross-sectional area is determined by the principle of equivalent axial stiffness. Numerical investigations on the dynamic behavior, aerostatic and aerodynamic stability of the two bridges are conducted by 3D nonlinear analysis, and the effect of different cable materials on the wind resistance is discussed. The results show that as CFRP cables are used in cable-supported bridges, (1) structural natural frequencies are all increased, and particularly great increase of the torsional frequency occurs for suspension bridges; (2) under the static wind action, structural deformation is increased, however its aerostatic stability is basically remained the same as that of the case with steel cables; (3) for suspension bridge, its aerodynamic stability is superior to that of the case with steel cables, but for cable-stayed bridge, it is basically the same as that of the case with steel stay cables. Therefore as far as the wind resistance is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable's cross-sectional area should be determined by the principle of equivalent axial stiffness.

Load Bearing Capacity of CLT - Concrete Connections with Inclined Screws (경사못이 적용된 CLT-콘크리트 접합부의 하중전달능력)

  • Kim, Kyung-Tae;Kim, Jong-Ho
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.4
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    • pp.3-13
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    • 2018
  • Load bearing capacity of dowel type fasteners loaded perpendicular to the shear plane is determined based on Johansen's yield theory (Johansen, 1949). In case of inclined screws whose axis is no longer perpendicular, the ultimate load of connection increases because of additional axial withdrawal capacity. To calculate load bearing capacity for inclined screws, KBC2016 and Eurocode5 provide design equations using the combination of two effects; axial and bending strength. Although their equations have been validated for a long time, there is still minimal information how to apply them for concrete-CLT joints. Since there are not many test data available, engineers have to make certain assumptions and thus results may look inconsistent in practice. In this paper, authors would like to describe the current approach and assumptions indicated by KBC2016 and Eurocode 5 and how they match the experimental results in terms of shear strength of CLT-concrete connections. To fulfill the objective, several push-out tests were performed on nine different test specimens. Each specimen has different penetration angles and depths. By analyzing load-displacement curves, the maximum shear strength, stiffness, and ductility were obtained. Shear strength values were compared with the current design codes and theoretical equations proposed in this paper. Observations on stiffness and ductility were briefly discussed.

Parametric study of shear capacity of beams having GFRP reinforcement

  • Vora, Tarak P.;Shah, Bharat J.
    • Advances in concrete construction
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    • v.13 no.2
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    • pp.183-190
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    • 2022
  • A wide range of experimental bases and improved performance with different forms of Fiber Reinforced Polymer (FRP) have attracted researchers to produce eco-friendly and sustainable structures. The reinforced concrete (RC) beam's shear capacity has remained a complex phenomenon because of various parameters affecting. Design recommendations for the shear capacity of RC elements having FRP reinforcement need a more experimental database to improve design recommendations because almost all the recommendations replace different parameters with FRP's. Steel and FRP are fundamentally different materials. One is ductile and isotropic, whereas the other is brittle and orthotropic. This paper presents experimental results of the investigation on the beams with glass fiber reinforced polymer (GFRP) reinforcement as longitudinal bars and stirrups. Total twelve beams with GFRP reinforcement were prepared and tested. The cross-section of the beams was rectangular of size 230 × 300 mm, and the total length was 2000 mm with a span of 1800 mm. The beams are designed for simply-supported conditions with the two-point load as per specified load positions for different beams. Flexural reinforcement provided is for the balanced conditions as the beams were supposed to test for shear. Two main variables, such as shear span and spacing of stirrups, were incorporated. The beams were designed as per American Concrete Institute (ACI) ACI 440.1R-15. Relation of VExp./VPred. is derived with axial stiffness, span to depth ratio, and stirrups spacing, from which it is observed that current design provisions provide overestimation, particularly at lower stirrups spacing.

Compressive Stress Distribution of High Tension Bolted Joints (고장력 볼트 이음부의 내부 압축응력 분포)

  • Kim, Sung Hoon;Lee, Seung Yong;Choi, Jun Hyeok;Chang, Dong Il
    • Journal of Korean Society of Steel Construction
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    • v.9 no.2 s.31
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    • pp.171-179
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    • 1997
  • The high-tension bolted joints are clamped by the axial force which approaches the yielding strength. The introduced axial force is transmitted to the connection members pass through washer. The transferred load in connections is balanced to the compressive stress of plates, axial force in bolts and the external loads. In this mechanism, the compressive stress and slip load we dominated by the effective stiffness of bolted joints and plates. In general the effective stiffness is specified to product to the effective area and elasticity modulus in connections. In this reason, the conic projection formular which is assumed that the axial force in bolts is distributed to the cone shape and that region is related to the elastic deformation mechanism in connections, was proposed. But it conclude what kind of formula is justified. Therefore in this paper, the fatigue tests are performed to the high tension bolted joints and inspected to the phase on the friction face. And using the FEM and numerical method, it is analyzed and approximated to the compressive stress distribution and its region. Moreover, it is estimated to the effective area and to the relation the friction area to the effective compressive distribution region.

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Analytical Study on the Prying Action Force and Axial Tensile Stiffness of High-Strength Bolts Used in an Unstiffened Extended End-Plate Connection (비보강 확장단부판 접합부에 체결된 고장력볼트의 지레작용력 및 축방향 인장강성에 대한 해석적 연구)

  • Kim, Hee Dong;Yang, Jae Guen;Lee, Hyung Dong
    • Journal of Korean Society of Steel Construction
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    • v.27 no.2
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    • pp.251-260
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    • 2015
  • The end plate connection is applied to beam-column moment connections in various forms. Such end plate connection displays changes in the behavioral characteristics, strength and stiffness, and energy dissipation capacity based on the thickness and length of the end plate, the number and diameter of the high strength bolt, the gauge distance of the high strength bolt, prying action force of the high strength bolt, and dimensions and length of the welds. Accordingly, this study has apprehended the axial tensile stiffness and prying action force of the high strength bolt connected on the tensile side based on the difference in thickness of the end plate, and was conducted to propose an analysis model for the prediction of such variables that affect the operating properties of the end plate. To achieve this, this study has conducted a three-dimensional non-linear finite-element analysis of the unstiffened expanding end plate connection by selecting only the thickness of the end plate as the variable.

Analysis on the Lateral Stiffness of Coil Spring for Railway Vehicle (철도차량용 코일스프링 횡강성 해석)

  • Hur, Hyun-Moo;Ahn, Da-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.9
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    • pp.84-90
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    • 2018
  • In constructing the multi-body dynamics model to analyze the behavior of the railway vehicle, it is very important to understand the properties of the suspension elements that constitute the suspension system. Among them, coil springs, which are mainly used in primary and secondary suspension systems, clearly show the axial stiffness in the drawings, but the lateral properties of the coil springs are not specified clearly, making it difficult to construct a dynamic analysis model. Therefore, in this paper, the model for analyzing the lateral stiffness of the coil spring is examined. A finite element method was applied to analyze the lateral stiffness of the coil spring and numerical analysis was performed by applying the coil spring lateral stiffness analysis model proposed by Krettek and Sobczak. And the test to analyze the lateral stiffness of coil spring was conducted. As a result of comparing with the test results, it was found that the results obtained by applying the lateral stiffness analysis model of Krettek and Sobczak and correcting the correction coefficient are similar to those of the test results.

An Effects of Lateral Reinforcement of High-Strength R/C Columns Subjected to Reversed Cyclic and High-Axail Force (고축력과 반복횡력을 받는 고강도 R/C기둥의 횡보강근 효과)

  • 신성우;안종문
    • Journal of the Korea Concrete Institute
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    • v.11 no.5
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    • pp.3-10
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    • 1999
  • Earthquake resistant R/C frame structures are generally designed to prevent the columns from plastic hinging. R/C columns under higher axial load or strong earthquake showed a brittle behavior due to the deterioration of strength and stiffness degradation. An experimental study was conducted to examine the behavior and to find the relationship between amounts of lateral reinforcements and compressive strength of ten R/C column specimens subjected to reversed cyclic lateral load and higher axial load. Test results are follows : An increase in the amount of lateral reinforcement results in a significant improvement in both ductility and energy dissipation capacities of columns. R/C columns with sub-tie provide the improved ductility capacity than those with closely spaced lateral reinforcement only. While the load resisting capacity of the high strength R/C columns is higher than the normal strength concrete columns under both an identical ratio of lateral reinforcement, however the ductility capacity of high strength R/C columns is decreased considerably. Therefore, the amounts of lateral reinforcement must be designed carefully to secure the sufficient ductility and economic design of HSC columns under higher axial load.

Evaluation on Deformation Capacity of CFT Square Columns subject to Constant Axial and Cyclic Lateral Loads (일정축력과 반복 수평력을 받는 콘크리트충전 각형강관 기둥의 변형성능 평가)

  • Ji, Ku Hyun;Choi, Sung Mo;Kim, Dong Kyu
    • Journal of Korean Society of Steel Construction
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    • v.12 no.2 s.45
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    • pp.209-219
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    • 2000
  • Concrete Filled steel Tube(CFT) Column has an excellent structural capacities in accordance with an interaction effect between the steel tube and concrete. Recently, CFT structure has been focussed on a structural system for a high-rise buildings. The purpose of this study is to evaluate a strength and deformation capacity of CFT square columns subjected to constant axial and cyclic lateral load. The test parameters are diameters to thickness ratio of steel tube, axial load ratios, concrete strengths, load applying types and whether or not filled concrete. Total sixteen specimens are fabricated to clarify the energy absorbtion capacity of CFT columns. Experimental results are summarized for maximum strength, initial stiffness and deformation capacity.

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