• Title, Summary, Keyword: lateral stiffness

Search Result 767, Processing Time 0.043 seconds

Improved electrode pattern design for lateral force increase in electrostatic levitation system

  • Woo, Shao-Ju;Jeon, Jong-Up;higuchi, Toshiro
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.311-314
    • /
    • 1996
  • In contactless disk handling systems based on electrostatic suspension in which the stator is to be transferred, the limited stiffness in lateral direction severely restricts the achievable translational acceleration. In existing stator electrode pattern designs, the magnitude of the lateral force is determined by the magnitude of the control voltages which are applied to the individual electrodes to levitate the disk stably. As a result, the lateral force cannot be set arbitrarily. A new stator electrode pattern is presented for the electrostatic levitation of disk-shaped objects, in particular silicon wafers and aluminum hard disks, which allows the lateral forces to be controlled independently from the levitation voltages. Therefore, greater lateral forces can be obtained, compared with the existing stator designs. Experimental results will be presented for a 4-inch silicon wafer that clearly reveal the increased lateral stiffness by using the proposed stator electrode compared to the conventional electrode pattern.

  • PDF

Modeling of the lateral stiffness of masonry infilled steel moment-resisting frames

  • Lemonis, Minas E.;Asteris, Panagiotis G.;Zitouniatis, Dimitrios G.;Ntasis, Georgios D.
    • Structural Engineering and Mechanics
    • /
    • v.70 no.4
    • /
    • pp.421-429
    • /
    • 2019
  • This paper presents an analytical model for the estimation of initial lateral stiffness of steel moment resisting frames with masonry infills. However, rather than focusing on the single bay-single storey substructure, the developed model attempts to estimate the global stiffness of multi-storey and multi-bay frames, using an assembly of equivalent springs and taking into account the shape of the lateral loading pattern. The contribution from each infilled frame panel is included as an individual spring, whose properties are determined on the basis of established diagonal strut macro-modeling approaches from the literature. The proposed model is evaluated parametrically against numerical results from frame analyses, with varying number of frame stories, infill openings, masonry thickness and modulus of elasticity. The performance of the model is evaluated and found quite satisfactory.

Equivalent Beam Model for Flat-Plate Building (무량판 건물의 등가 보 모델)

  • 박수경;김두영;박성무
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.312-316
    • /
    • 1995
  • Flat-plate buildings are commonly modeled as two-dimensional frames to calculate lateral drift, unbalanced moments, and shear at slab-column connections. For gravity loads. the slab-column frames are analyzed using equivalent column approach, while equivalent beam approach is typical for lateral loads. The equivalent beam approach is convenient for computer analysis, but no rational procedure exists for determining the effective width of foor slabs. At present, the determination of the equivalent slab width and its stiffness is a matter of engineering judgement. To account for cracking, overly conservative assumptions are made regarding the stiffness of the slab. A rational approach is therefore needed to realistically estimate the equivalent slab width and its stiffness for unbalanced moment and lateral drift calculations. Based on the test results of 8 interior slab-column connections, an equivalent beam model is proposed in which columns are modeled conventionally as a function of column and slab aspect ratios and the magnitude of the gravity load. the proposed approach is verified with selected experimental results and is founded to be practical and convenient for analyzing flat-plate buildings subjected to gravity and lateral loading.

  • PDF

Vibration Analysis of Geared Rotor System (기어전동 회전축계의 진동해석)

  • Kim, K.D.;Kim, Y.H.;Yang, B.S.;Lee, S.J.
    • Journal of the Korea Society For Power System Engineering
    • /
    • v.4 no.1
    • /
    • pp.60-67
    • /
    • 2000
  • As the speed of rotating machines increases and also their weight decreases, the coupling between lateral and torsional vibrations must be considered. In the past, rotordynamics and geardynamics have tended to treat the lateral and torsional vibrations of the system elements as separate and decoupled mechanisms. In the paper, the coupled lateral-torsional free and forced vibration of rotors trained by gears is analyzed using finite element method. Also the complicated variation of the meshing stiffness as a function of contact point along the line of action is estimated correctly. The gear mesh model is assumed to be linear with constant average mesh stiffness.

  • PDF

Dynamic Sensitivity Analysis For Lateral Drift Control Of Frame-Shear Wall Structures (골조-전단벽 구조물의 횡변위제어를 위한 동적 민감도 해석)

  • Lee, Han-Joo;Kim, Ji-Youn;Han, Seung-Baek;Nam, Kyung-Yun;Kim, Ho-Soo
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • /
    • pp.571-576
    • /
    • 2007
  • This study presents stiffness-based optimal design to control quantitatively lateral drift of frame-shear wall structures subject to seismic loads. To this end, lateral drift constraints are established by introducing approximation concept that preserves the generality of the mathematical programming and can efficiently solve large scale problems. Also, the relationships of sectional properties are established to reduce the number of design variables and resizing technique of member is developed under the 'constant-shape' assumption. Specifically, the methodology of dynamic displacement sensitivity analysis is developed to formulate the approximated lateral displacement constraints. The 12 story frame-shear wall structural models is considered to illustrate the features of dynamic stiffness-based optimal design technique proposed in this study.

  • PDF

Stiffness Reduction Factor for Flat Plate Slabs (플랫 플레이트 슬래브 해석을 위한 강성감소계수 제안)

  • Park, Young-Mi;Han, Sang-Whan
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.337-340
    • /
    • 2006
  • The purpose of this study is to propose the stiffness reduction factor for flat plate slabs under lateral loads. Current design code (e.g., ACI 318-05) requires considering the effects of cracks for calculating slab stiffness under lateral loads. This study collected the test results of 20 interior slab-column connections, from which stiffness reduction in each test was estimated with respect to the ratio of applied moment to cracking moment ($M_a/M_{cr}$). Based on collected data, this study proposed equations for calculating stiffness reduction with respect to $M_a/M_{cr}$. To verify the proposed equations, this study conducted the experimental test of interior slab-column connections under quasi-static cyclic loading. From the test, load-deformation curve is compared to that obtained from effective beam width method with the proposed equation for the stiffness reduction. It is shown that the effective beam width method with the proposed equation for stiffness reduction predicts accurately the test results.

  • PDF

Proposal for Optimal Outrigger Location Considering Stiffness of Frame (프레임의 강성을 고려한 최적 아웃리거 위치의 제안)

  • Kim, Hyong-Kee
    • Journal of the Architectural Institute of Korea Structure & Construction
    • /
    • v.35 no.9
    • /
    • pp.183-190
    • /
    • 2019
  • This paper intended to propose the optimal outrigger position in tall building. For this purpose, a schematic structure design of 70 stories building was accomplished by using MIDAS-Gen. In this analysis research, the key variables were the stiffness of outrigger, the stiffness of frame, the stiffness of shear wall, the stiffness of exterior column connected in outrigger and the outrigger location in height. With the intention of looking for the optimum location of outrigger system in high-rise building, we investigated the lateral displacement in top floor. The study proposed the new method to predict the optimal location of outrigger system considering the frame stiffness. And it is verified that the paper results can be helpful in providing the important engineering materials for finding out the optimum outrigger position in tall building.

Influence of masonry infill on reinforced concrete frame structures' seismic response

  • Muratovic, Amila;Ademovic, Naida
    • Coupled systems mechanics
    • /
    • v.4 no.2
    • /
    • pp.173-189
    • /
    • 2015
  • In reality, masonry infill modifies the seismic response of reinforced concrete (r.c.) frame structures by increasing the overall rigidity of structure which results in: increasing of total seismic load value, decreasing of deformations and period of vibration, therefore masonry infill frame structures have larger capacity of absorbing and dissipating seismic energy. The aim of the paper is to explore and assess actual influence of masonry infill on seismic response of r.c. frame structures, to determine whether it's justified to disregard masonry infill influence and to determine appropriate way to consider infill influence by design. This was done by modeling different structures, bare frame structures as well as masonry infill frame structures, while varying masonry infill to r.c. frame stiffness ratio and seismic intensity. Further resistance envelope for those models were created and compared. Different structures analysis have shown that the seismic action on infilled r.c. frame structure is almost always twice as much as seismic action on the same structure with bare r.c. frames, regardless of the seismic intensity. Comparing different models resistance envelopes has shown that, in case of lower stiffness r.c. frame structure, masonry infill (both lower and higher stiffness) increased its lateral load capacity, in average, two times, but in case of higher stiffness r.c. frame structures, influence of masonry infill on lateral load capacity is insignificant. After all, it is to conclude that the optimal structure type depends on its exposure to seismic action and its masonry infill to r.c. frame stiffness ratio.

A Detailed 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
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.722-728
    • /
    • 2001
  • 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 in 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 analyses natural vibration frequencies and their mode shapes upon varying the gear mesh stiffness, and also by comparing the strain energies of lateral and torsional vibration modes. Results have shown that some modes may have 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, i.e., the dominant mode changes from an initial torsional one to a lateral one or from an initial lateral one to a torsional one.

  • PDF

Lateral Vibration Analysis of a Small Scale Railway Vehicle Model (축소형 차량의 횡진동 해석)

  • Lee Seung-Il;Son Gun-Ho;Choi Yeon-Sun
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.417-422
    • /
    • 2004
  • The vibration of a running 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 small scale railway vehicle model. Also, the effects on the car body, bogie and wheelset were examined for the weight and the stiffness of the first and second suspension. The experimental results showed that the lateral vibration increases as the wheel conicity and stiffness of the second suspension 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.

  • PDF