• Title, Summary, Keyword: lateral stiffness

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A Study on Lateral Buckling of Beam String Structures (보-스트링 구조의 횡 좌굴에 관한 연구)

  • Kim, Jae-Yeol
    • Journal of the Korean Association for Spatial Structures
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    • v.13 no.4
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    • pp.49-56
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    • 2013
  • Beam string structures(BSS) are one kind of efficient structure system because the bending moment in the beams is reduced greatly through the struts and the strings. As the struts in BSS are used as middle supports to the beam and always in compression, the buckling of the struts should be avoided. This paper investigates the lateral buckling of the struts in BSS. Firstly, the strut of a one-strut BSS is simplified into an analytical model by considering load is formulated and some special cases of the model are analyzed. Finally, the lateral buckling load of the strut is numerically examined by means of parameter studies. It is known that, because on end of the struts is jointed to the beam while the other end is connected to the strings, the buckling of the struts not only depends on the length of the struts and the stiffness of the joints, but also depends on the rise and the lateral stiffness of the beam, the layout of the strings and the number of the struts.

Effect of bridge lateral deformation on track geometry of high-speed railway

  • Gou, Hongye;Yang, Longcheng;Leng, Dan;Bao, Yi;Pu, Qianhui
    • Steel and Composite Structures
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    • v.29 no.2
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    • pp.219-229
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    • 2018
  • This paper presents an analytical model to analyze the mapping relationship between bridge lateral deformation and track geometry of high-speed railway. Based on the rail deformation mechanisms, the deformation of track slab and rail at the locations of fasteners are analyzed. Formulae of rail lateral deformation are derived and validated against a finite element model. Based on the analytical model, a rail deformation extension coefficient is presented, and effects of different lateral deformations on track geometry are evaluated. Parametric studies are conducted to evaluate the effects of the deformation amplitude, fastener stiffness and mortar layer stiffness on the rail deformation. The rail deformation increases with the deformation of the girder, and is dependent on the spacing of the fasteners, the elastic modulus of the rail's material, and the moment of inertia of the rail's section.

A Detail Investigation on Coupled Lateral and Torsional Vibration Characteristics in a Speed Increasing Geared Rotor-bearing System (증속 기어전동 로터-베어링 시스템에서 횡-비틀림 연성진동 특성의 상세 고찰)

  • 이안성;하진웅;최동훈
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.2
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    • pp.116-123
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    • 2002
  • Applying a general coupled lateral and torsional vibration finite element model of gear pair element, this paper intends to look into in detail the coupled lateral and torsional vibration characteristics of a turbo-chiller rotor bearing system, having a bull-pinion speed increasing gear. Investigations have been carried out systematically by comparing the uncoupled and coupled natural frequencies and their mode shapes upon varying the gear mesh stiffness with considerations on rotating speeds, and also by comparing the strain energies of lateral and torsional vibration modes. Results hale shown that some modes may hale the coupled lateral and torsional mode characteristics as the gear mesh stiffness Increases over a certain value, and moreover that their associated dominant modes may be different from their initial modes, j.e., a certain dominant mode may change from an initial torsional one to a lateral one or from an initial lateral one to a torsional one.

Lateral Vibration Analysis for Design Parameter of the Scale Model of a Railway Vehicle (축소형 철도차량의 설계변수에 따른 횡진동 해석)

  • Lee, Seung-Il;Choi, Yeon-Sun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.12
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    • pp.1231-1237
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    • 2006
  • The vibration of a running railway vehicle can be classified on lateral, longitudinal and vertical motions. The important factor on the stability and ride quality of a railway vehicle is the lateral motion. The contact between wheel and rail with conicity influences strongly on the lateral motion. In this study, an experiment for the vibration of a running railway vehicle was performed using a of the scale model of a railway vehicle. Also, the effects on the car-body, bogie and wheelset were examined for the weight and the stiffness of the second suspension system. The experimental results showed that the lateral vibration increases as the wheel conicity and stiffness of the second suspension system increase. And the lateral vibration of the bogie increases as the mass ratio between car-body and bogie increases. Also, the lateral vibration of the wheel becomes high at low speed, while the wheel of 1/20 conicity makes severe vibration at high speed running.

Design, Fabrication and Test of Piezoelectric Actuator Using U-Shape PZT Strips and Lever Structure for Lateral Stroke Amplification (수평방향 변위증폭을 위해 U-형상의 PZT 스트립과 지렛대 구조를 이용한 압전구동형 액추에이터의 설계, 제작 및 실험)

  • 이준형;이택민;최두선;황경현;서영호
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.12
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    • pp.1937-1941
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    • 2004
  • We present lateral actuated piezoelectric actuator using U-shaped PZT strip and lever structure for the RF switch application. In the previous study of RF switch, they used horizontal contact switch fabricated by thin film metals. However, thin film metals could not generate large contact force due to low stiffness. In this work, we suggest lateral contact switch which makes large contact force by increasing stiffness. In addition, we use PZT actuator for the high force actuation. Generally actuator using thin film PZT moves to the vertical direction due to the neutral axis shift. Therefore we need lateral motion generation mechanism based on the thin film PZT actuator. In order to increase lateral motion of thin film PZT actuator, we use U-shaped PZT actuator using residual stress control. Also, thin film PZT actuator can generate very small lateral motion of 120${\times}$10$^{-6}$ ${\mu}{\textrm}{m}$/V for d$_{31}$ mode, thus we suggest lever structure to increase stroke amplification. From the experimental study, fabricated PZT actuator shows maximum lateral displacement of 1 ${\mu}{\textrm}{m}$, and break down voltage of the thin film PZT actuator is above 16V.

Static Analysis of Axisymmetric Circular Plates under Lateral Loading Using Transfer of Stiffness Coefficient (강성계수의 전달을 이용한 횡방향 하중을 받는 축대칭 원판의 정적해석)

  • Choi, Myung-Soo;Yeo, Dong-Jun
    • Journal of the Korea Society For Power System Engineering
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    • v.18 no.6
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    • pp.64-69
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    • 2014
  • A circular plate is one of the important structures in many industrial fields. In static analysis of a circular plate, we may obtain an exact solution by analytical method, but it is limited to a simple circular plate. Thus, many researchers and designers have used numerical methods such as the finite element method. The authors of this paper developed the finite element-transfer stiffness coefficient method (FE-TSCM) for static and dynamic analyses of various structures. FE-TSCM is the combination of the modeling technique of the finite element method (FEM) and the transfer technique of the transfer stiffness coefficient method (TSCM). FE-TSCM has the advantages of both FEM and FE-TSCM. In this paper, the authors formulate the computational algorithm for the static analysis of axisymmetric circular plates under lateral loading using FE-TSCM. The computational results for three computational models obtained by FE-TSCM are compared with those obtained by FEM in order to confirm the accuracy of FE-TSCM.

Inelastic displacement ratios for evaluation of stiffness degrading structures with soil structure interaction built on soft soil sites

  • Aydemir, Muberra Eser
    • Structural Engineering and Mechanics
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    • v.45 no.6
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    • pp.741-758
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    • 2013
  • In this study, inelastic displacement ratios are investigated for existing systems with known lateral strength considering soil structure interaction. For this purpose, SDOF systems for period range of 0.1-3.0 s with different hysteretic behaviors are considered for a number of 18 earthquake motions recorded on soft soil. The effect of stiffness degradation on inelastic displacement ratios is investigated. The Modified Clough model is used to represent structures that exhibit significant stiffness degradation when subjected to reverse cyclic loading and the elastoplastic model is used to represent non-degrading structures. Soil structure interaction analyses are conducted by means of equivalent fixed base model effective period, effective damping and effective ductility values differing from fixed-base case. For inelastic time history analyses, Newmark method for step by step time integration was adapted in an in-house computer program. A new equation is proposed for inelastic displacement ratio of system with SSI with elastoplastic or degrading behavior as a function of structural period ($\tilde{T}$), strength reduction factor (R) and period lengthening ratio ($\tilde{T}$/T). The proposed equation for $\tilde{C}_R$ which takes the soil-structure interaction into account should be useful in estimating the inelastic deformation of existing structures with known lateral strength.

Enhancing seismic performance of ductile moment frames with delayed wire-rope bracing using middle steel plate

  • Ghalandari, Akram;Ghasemi, Mohammad Reza;Dizangian, Babak
    • Steel and Composite Structures
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    • v.28 no.2
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    • pp.139-147
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    • 2018
  • Moment frames have considerable ductility against cyclic lateral loads and displacements; however, sometimes this feature causes the relative displacement to exceed the permissible limits. This issue can bring unfavorable hysteretic behavior on the frame due to the reduction in the stiffness and resistance against lateral loads. Most of common bracing systems usually control lateral displacements through increasing stiffness while result in decreasing the capacity for energy absorption. This has direct effect on hysteresis curves of moment frames. Therefore, a system that is capable of both having the capacity of energy absorption as well as controlling the displacements without a considerable increase in the stiffness is quite important. This paper investigates retrofitting of a single-storey steel moment frame using a delayed wire-rope bracing system equipped with the ductile middle steel plate. The steel plate is considered at the middle intersection of wire ropes, where it causes cables to be continuously in tension. This integrated system has the advantage of reducing considerable stiffness of the frame compared to cross bracing systems as a result of which it could also preserve the frame's energy absorption capacity. In this paper, FEM models of a delayed wire-rope bracing system equipped by steel plates with different geometries have been studied, validated, and compared with other researchers' laboratory test results.

Influence of Pile Cap's Boundary Conditions in Piled Pier Structures (교량 말뚝기초의 단부 지점조건의 영향분석)

  • Won Jin-Oh;Jeong Sang-Seom
    • Journal of the Korean Geotechnical Society
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    • v.21 no.5
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    • pp.15-24
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    • 2005
  • Modeling techniques of piled pier were reviewed and the influences of pile cap's boundary conditions were analyzed in this study. The method using flexible springs seems to be useful fur the practical design since its simplified model can represent the complex behaviors of pile groups efficiently. Parameter studies were performed far various pile group arrangements, pile spacings, end bearing conditions, and loading stages to analyze their effects on the lateral displacements, maximum pile bending stresses, and lateral stiffness of pile groups. Through the parameter studies, it was found that when lateral stiffness of pile groups was estimated by using three-dimensional analysis method (YSGroup), its complex behavior could be predicted better than other methods based on single pile analysis.

Seismic analysis of RC tubular columns in air-cooled supporting structure of TPP

  • Wang, Bo;Yang, Ke;Dai, Huijuan;Bai, Guoliang;Qin, Chaogang
    • Earthquakes and Structures
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    • v.18 no.5
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    • pp.581-598
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    • 2020
  • This paper aims to investigate the seismic behavior and influence parameters of the large-scaled thin-walled reinforced concrete (RC) tubular columns in air-cooled supporting structures of thermal power plants (TPPs). Cyclic loading tests and finite element analysis were performed on 1/8-scaled specimens considering the influence of wall diameter ratio, axial compression ratio, longitudinal reinforcement ratio, stirrup reinforcement ratio and adding steel diagonal braces (SDBs). The research results showed that the cracks mainly occurred on the lower half part of RC tubular columns during the cyclic loading test; the specimen with the minimum wall diameter ratio presented the earlier cracking and had the most cracks; the failure mode of RC tubular columns was large bias compression failure; increasing the axial compression ratio could increase the lateral bearing capacity and energy dissipation capacity, but also weaken the ductility and aggravate the lateral stiffness deterioration; increasing the longitudinal reinforcement ratio could efficiently enhance the seismic behavior; increasing the stirrup reinforcement ratio was favorable to the ductility; RC tubular columns with SDBs had a much higher bearing capacity and lateral stiffness than those without SDBs, and with the decrease of the angle between columns and SDBs, both bearing capacity and lateral stiffness increased significantly.