• Title/Summary/Keyword: initial stiffness factor

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A Study on the Development of High Stiffness Body for Suspension Performance (서스펜션 성능 확보를 위한 고강성 차체 개발 프로세스 연구)

  • Kim, Ki-Chang;Kim, Chan-Mook
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.358-361
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    • 2004
  • This paper describes the development process of high stiffness body for ride and handling performance. High stiffness and light weight vehicle is a major target in the refinement of passenger cars to meet customers' contradictable requirements between ride and handling performance and fuel economy. This paper describes the analysis approach process for high stiffness body through the data level of body stiffness. According to the frequency band, we can suggest the design guideline about Is cornering static stiffness, torsional and lateral stiffness, body attachment stiffness. The ride and handling characteristic of a vehicle is significantly affected by vibration transferred to the body through the chassis mounting points from front and rear suspension. It is known that body attachment stiffness is an important factor of ride and handling performance improvement. And high stiffness helps to improve the flexibility of bushing rate tuning between Handling and road noise. It makes it possible to design the good handling performance vehicle at initial design stage and save vehicles to be used in tests by using mother car at initial design stage. These improvements can lead to shortening the time needed to develop better vehicles.

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Initial stiffness and moment capacity assessment of stainless steel composite bolted joints with concrete-filled circular tubular columns

  • Wang, Jia;Uy, Brian;Li, Dongxu
    • Steel and Composite Structures
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    • v.33 no.5
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    • pp.681-697
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    • 2019
  • This paper numerically assesses the initial stiffness and moment capacity of stainless steel composite bolted joints with concrete-filled circular tubular (CFCT) columns. By comparing with existing design codes including EN 1993-1-8 and AS/NZS 2327, a modified component method was proposed to better predict the flexural performance of joints involving circular columns and curved endplates. The modification was verified with independent experimental results. A wide range of finite element models were then developed to investigate the elastic deformations of column face in bending which contribute to the corresponding stiffness coefficient. A new design formula defining the stiffness coefficient of circular column face in bending was proposed through regression analysis. Results suggest that a factor for the stiffness coefficient of endplate in bending should be reduced to 0.68, and more contribution of prying forces needs to be considered. The modified component method and proposed formula are able to estimate the structural behaviour with reasonable accuracy. They are expected to be incorporated into the current design provisions as supplementary for beam-to-CFCT column joints.

Experimental study on seismic performance of steel reinforced concrete T-shaped columns

  • Liu, Zuqiang;Zhou, Chaofeng;Xue, Jianyang;Leon, Roberto T.
    • Steel and Composite Structures
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    • v.36 no.3
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    • pp.339-353
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    • 2020
  • This study investigates the seismic performance of steel reinforced concrete (SRC) T-shaped columns under low cyclic loading tests. Based on test results of ten half-scale column specimens, failure patterns, hysteretic behavior, skeleton curves, ultimate strength, ductility, stiffness degradation and energy dissipation capacity were analyzed. The main variables included loading angles, axial compression ratios and steel ratios. The test results show that the average values of the ductility factor and the equivalent viscous damping coefficient with respect to the failure of the columns were 5.23 and 0.373, respectively, reflecting good seismic performance. The ductility decreased and the initial stiffness increased as the axial compression ratio of the columns increased. The strength increased with increasing steel ratio, as expected. The columns displaced along the web had higher strength and initial stiffness, while the columns displaced along the flange had better ductility and energy dissipation capacity. Based on the test and analysis results, a formula is proposed to calculate the effective stiffness of SRC T-shaped columns.

A Study on the Development of High Stiffness Body for Suspension Performance (서스펜션 성능 확보를 위한 고강성 차페 개발 프로세스 연구)

  • Kim, Ki-Chang;Kim, Chan-Mook
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.7 s.100
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    • pp.799-805
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    • 2005
  • This paper describes the development process of high stiffness body for ride and handling performance. High stiffness and light weight vehicle is a major target in the refinement of Passenger cars to meet customers' contradictable requirements between ride and handling performance and fuel economy This paper describes the analysis approach process for high stiffness body through the data level of body stiffness. According to the frequency band. we can suggest the design guideline about lg cornering static stiffness, torsional and lateral stiffness, body attachment stiffness. The ride and handling characteristic of a vehicle Is significantly affected by vibration transferred to the body through the chassis mounting points from front and rear suspension. It is known that body attachment stiffness is an important factor of ride and handling performance improvement. And high stiffness helps to improve the flexibility of bushing rate tuning between handling and road noise. It makes possible to design the good handling performance vehicle and save vehicles to be used in tests by using mother car at initial design stage. These improvements can lead to shortening the time needed to develop better vehicles.

Nonlinear Hysteretic Behavior of Hybrid Steel Beams with Reinforced Concrete Ends (단부 철근콘크리트 중앙부 철골조로 이루어진 혼합구조부의 비선형 이력거동)

  • 이은진;김욱종;문정호;이리형
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.2
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    • pp.379-387
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    • 2002
  • This paper presents an analytical model on nonlinear hysteretic behavior of hybrid steel beam with reinforced concrete ends. The modeling method and appropriate coefficients with IDARC2D were proposed from the comparison with previous test results. Since the polygonal model of IDARC2D nay overestimate, new analytical model with the initial stiffness reduction coefficient was proposed. The hysteretic coefficients for the analysis of the hybrid steel beam with reinforced concrete ends were also presented. The analytical results were compared with previous experiments. The initial stiffness and the strength were predicted with less than 5% error and 10% error, respectively.

Disturbance Compensation Control Design far 2-DOF Gun Stabilization System with Gear Stiffness by Using FXLMS Algorithm (기어강성을 갖는 2-자유도 포신 안정화시스템에서 FXLMS 알고리즘을 이용한 외란 보상 제어기 설계)

  • Lim, Jae-Keun;Kang, Min-Sig
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.488-493
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    • 2005
  • In gun stabilization systems, the torque comes from the unbalance mass of gun and the base acceleration is an important source of disturbance which degrades stabilization performance. Fatigue of gear train is another important factor affecting structural safety problems. In this paper, a feedback control gain is designed by optimal control weighting to difference between motor and gun velocity, and a feedforward controller using FXLMS algorithm is adopted to investigate those problems. Experimental results show that the feedforward compensator based on FXLMS can reduce the disturbance effects. The directional convergence property according to initial conditions of the FXLMS is also shown through experiments.

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A Study of Unstable Phenomenon of Flow Truss Dome Structure with Asymmetric Load Modes (Flow Truss Dome 구조물의 비대칭 하중모드에 따른 불안정 현상에 관한 연구)

  • Shon, Su-Deok;Kim, Seung-Deog;Kang, Moon-Myung
    • Journal of Korean Association for Spatial Structures
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    • v.2 no.4 s.6
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    • pp.61-76
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    • 2002
  • The structure system that is discreterized by continuous shells is usually used to make a large space structures and these structures show the collapse mechanisms that are captured at over the limit load, and snap-through and bifurcation are most well known of it. For the collapse mechanism, rise-span ratio, element stiffness and load mode are main factor, which it give an effect to unstable behavior. Moreover, resist force of structure can be reduced by initial condition and initial imperfection significantly. In order to investigate the instability of shell structures, the finite deformation theory can be applied and it becomes a nonlinear mathematics in which use equation of tangential stiffness incrementally. With an initial imperfection, using simple example and Flow Truss Dome, the buckling characteristics of space truss is main purpose of this paper, and unstable behavior is studied by proposed the numerical method. Also, by using MIDAS, this research work analyzes displacements and inner forces as the design load of model, and the ratio of buckling load of design load is investigated.

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Behavior of fully- connected and partially-connected multi-story steel plate shear wall structures

  • Azarafrooza, A.;Shekastehband, B.
    • Structural Engineering and Mechanics
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    • v.76 no.3
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    • pp.311-324
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    • 2020
  • Until now, a comparative study on fully and partially-connected steel shear walls leading to enhancing strength and stiffness reduction of partially-connected steel plate shear wall structures has not been reported. In this paper a number of 4-story and 8-story steel plate shear walls, are considered with three different connection details of infill plate to surrounding frame. The specimens are modeled using nonlinear finite element method verified excellently with the experimental results and analyzed under monotonic loading. A comparison between initial stiffness and shear strength of models as well as percentage of shear force by model boundary frame and infill plate are performed. Moreover, a comparison between energy dissipation, ductility factor and distribution of Von-Mises stresses of models are presented. According to the results, the initial stiffness, shear resistance, energy dissipation and ductility of the models with beam-only connected infill plates (SSW-BO) is found to be about 53%, 12%, 15% and 48% on average smaller than those of models with fully-connected infill plates (SPSW), respectively. However, performance characteristics of semi-supported steel shear walls (SSSW) containing secondary columns by simultaneously decreasing boundary frame strength and increasing thickness of infill plates are comparable to those of SPSWs. Results show that by using secondary columns as well as increasing thickness of infill plates, the stress demands on boundary frame decreases substantially by as much as 35%. A significant increase in infill plate share on shear capacity by as much as 95% and 72% progress for the 4-story SSW-BO and 8-story SSSW8, respectively, as compared with non-strengthened counterparts. A similar trend is achieved by strengthening secondary columns of 4-story SSSW leading to an increase of 50% in shear force contribution of infill plate.

Energy Ratio Factor and Phase Angle Based Fatigue Prediction Model for Flexible Pavements

  • Kim, Nak-Seok
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.2
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    • pp.75-80
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    • 2011
  • The main objective of this research is to develop fatigue prediction model for flexible pavements using energy ratio factor and phase angle. The two parameters are considered as fundamental properties of time and temperature dependent viscoelastic asphalt concrete materials. The energy ratio factor is defined as the ratio of the pseudo-total cumulative dissipated energy to the cumulative dissipated energy to failure during the test. The phase angle between the stress and strain ware signals stems from the intrinsic the dependent asphalt mixture behavior. The phase angle was computed and the relationship between the initial mixture stiffness and the initial phase angle is presented. As a result, fatigue prediction model for flexible pavements was proposed using intrinsic properties of viscoelastic asphalt concrete materials.

Out-of-plane buckling and bracing requirement in double-angle trusses

  • Chen, Shaofan;Su, Mingzhou
    • Steel and Composite Structures
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    • v.3 no.4
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    • pp.261-275
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    • 2003
  • Truss members built-up with double angles back-to-back have monosymmetric cross-section and twisting always accompanies flexion upon the onset of buckling about the axis of symmetry. Approximate formulae for calculating the buckling capacity are presented in this paper for routine design purpose. For a member susceptible only to flexural buckling, its optimal cross-section should consist of slender plate elements so as to get larger radius of gyration. But, occurrence of twisting changes the situation owing to the weakness of thin plates in resisting torsion. Criteria for limiting the leg slenderness are discussed herein. Truss web members in compression are usually considered as hinged at both ends for out-of-plane buckling. In case one (or both) end of member is not supported laterally by bracing member, its adjoining members have to provide an elastic support of adequate stiffness in order not to underdesign the member. The stiffness provided by either compression or tension chords in different cases is analyzed, and the effect of initial crookedness of compression chord is taken into account. Formulae are presented to compute the required stiffness of chord member and to determine the effective length factor for inadequately constrained compressive diagonals.